Staghorn Ferns as Houseplants in NYC

The curled, more rigid feel to the leaves of this staghorn fern in the office implies that it is not in as humid an environment as it would like, but regular misting and watering are certainly helping to keep it going.

Question(s):
i'm a big fan of your blog. i'm a patio/indoor gardener and have recently become rather obsessed with ferns - my boyfriend (who's a landscaper and gardener as well) gave me a staghorn fern as a gift. i have been googling the fern and have read some contrasting advice (it loves bright light, it should be in a shady spot; don't over water and even allow it to slightly wilt so you know you aren't OR always keep the soil evenly damp). Since it's a gift i really want to keep it alive - it's also such a beautiful plant that i would hate to be responsible for killing it.

SO. here's the deal - the fern is rather large and it came in a six inch plastic hanging pot. i have read that i should transplant it into a hanging wire basket lined with sphagnum moss and hang the plant sideways and growth will come out of all sides. would you agree with that? should i line it with the moss and then add peat and then the fern? (also something i read).

in terms light -- my gut instinct with all ferns is to give them part shade. none of my windows get direct bright light but rather i have three big windows with varying levels: bright indirect, medium indirect and low indirect - it is currently in the medium indirect. my patio gets direct light and part of it is always in the shade. would you recommend i keep the fern outside until fall - before any danger of frost?

watering -- always damp? also: would you recommend misting the plant since it like humidity? or is misting pointless?

i think that's about it. please let me know if you have any questions and i really, really appreciate your help with this.

Answer(s):
A staghorn fern (Platycerium bifurcatum) is without question a beautiful and unusual plant, and I personally think they are fabulous. However, I am very glad that you both have plenty of plant growing experience because you will need it as they are not necessarily the easiest houseplant out there. In fact, some books outright say these plants are not suitable for the home, but I think you can prove them wrong. Let me share with you what I know from my experience with them, both in greenhouses and in the home, as well as refer to some great houseplant books we have here in the HSNY Library. Your fern will be a little particular, but with the right care I think you should be able to keep it going for plenty of years to come.

Your fern will produce two types of leaves as it grows. The sterile fronds will be produced at the base of the plant and mature from green to brown. In its natural environment these fronds would adhere themselves to the larger tree branch the fern would be living on, eventually pulling nutrients from the organic matter that would collect between the two organisms. Transplanting it into a wire or wooden (orchid) basket with sphagnum moss is what I would do. Because it is a naturally epiphytic plant the moss should hold enough moisture at the base of the plant between when you water. I would transplant the fern oriented as you want it because the sterile fronds will naturally grown down and around the base of the plant (and the sphagnum moss) as the fertile fronds will continue to grow upright and out in search of light and humidity. My gut instinct is that the extra step of incorporating the peat moss is not necessary, but if it is in a peat-heavy mix now then that might help the transition to be as smooth as possible. I actually bought one mostly in peat moss one time and transplanted it into sphagnum moss soon after getting it. It definitely went through a little shock and stress (granted it was also adapting to my light and humidity) but it survived and I think was happier in the long run being in the sphagnum. I wonder if you might want to keep it in the plastic for a bit longer to make sure it is acclimated to the light and humidity of your place before transplanting, but that is probably me being too conservative.

Light is one of those issues where we have to remember that we live in the city with light levels that are uniquely different than if we were in the country. I would think it would be happiest in as sunny a spot as you can get it. Especially if you received it as a pretty mature plant, I’m guessing it was getting a lot of light in the greenhouse where it was raised. One of my favorite references recommends bright light with some direct sun and that sounds pretty right on to me. When I helped care for staghorn ferns up at NYBG when I was a student they were kept in a house that got a flood of bright, barely diffused light, and they loved it. Here in my office I have one that actually gets a good shot of direct morning sun and I was fearing it might be too much, but the plant is holding up well. If we were in the country I would say otherwise, that some shade would be good, but here we are often searching to find sunlight for our plants before we are searching to find them shade. As far as the debate between inside versus outside, I would try and figure out which area will have higher humidity and stick it there. If you put it outside do not let the nighttime temperature get much below 65 before pulling it inside. It sounds to me like the medium indirect or bright indirect perches inside would be suitable.

Once you have your fern situated in the sphagnum moss I think you should only have to water it about once a week, the same routine as you might water orchids. In addition, once a month or so I would give it a real good drench, even submerge the base of the plant in water for a few minutes, and then let it drain. This can also be a good time to incorporate a light fertilizing, which should be done once a month during the summer months but not so much in the darker seasons. Watering from the base will be a good practice because too much water at the base of the fertile fronds can lead them to get too waterlogged and fall off, and you definitely do not want to lose leaves as staghorn ferns are slow growers. If the plant dries out a little bit between watering that is fine.

I am glad you brought up misting and humidity because this is really the most important thing when it comes to keeping a staghorn fern alive in the home. They require a lot of regular humidity, and drying out too much can be the ultimate downfall of the plant (trust me – I know!). In a greenhouse setting staghorn ferns do great because they get the 60% humidity (or higher) all the time which is ideal. At home I keep mine in the bathroom, where the light and humidity are ample, but even then I mist it occasionally, especially if we have been away for a few days. Here in our office I am always misting the staghorn fern and it seems like I can never do that enough. Again, I try to mist regularly but prevent lots of water from collecting at the base of the fertile fronds. What can I say, I know the plant is a little bit drier than it would prefer, but it is holding on and looking good.

The only other thing that comes to mind is the waxy coating on the surface of the fertile green leaves. That waxy coating helps the plant to retain more moisture in its leaves so do not attempt as some do to clean the leaves and remove it. If some gets wiped off when you transplant that is not the end of the world by any means. It sounds like you know plant care enough not to do that, but worth the quick mention regardless.

I guess the long and the short of it is that you simply can’t forget or neglect a staghorn fern as a houseplant. But if I can keep one alive in a dry office setting then I am sure yours will be just fine once you get it more situated and on a regular regiment. Good luck and let me know how it works out for you.

Plant ID: Amaranthus tricolor

Question:
PLEASE TELL ME WHAT THIS FLOWER OR WEED IS, ITS BEAUTIFUL.

Answer:
Chances are the plant you have photographed is neither a flower or a weed. What you have there in that photograph is actually a tropical plant that someone decided to grow as a large annual in their garden for the summer. I will admit that at first I was stumped, but luckily I have a good friend and mentor who happens to be a curator at the New York Botanical Garden so he was able to enlighten both of us.

Amaranthus tricolor, commonly called summer poinsettia, is a plant indigenous to Africa and Asia loved for its ornamental value and colorful foliage. Another common name is Chinese spinach, and rightfully so as it is grown as a leaf vegetable in some locations. Because it is hardy in USDA Zones 9-11 we would consider it a tropical plant up here in New York and only be able to grow it as an annual outdoors. There is one cultivar named ‘Joseph’s Coat’ which has a striking combination of yellow and red atop its otherwise green leaves. Thanks again to Marc we are guessing you spotted a specific cultivar named ‘Illumination’ which has those bright red leaves above the olive/red variegated leaves at its base and reaches about 42” tall. From what I understand they used to be planted more often as annuals in the garden but you do not see them in cultivation much any more.

Thanks for writing. I always love learning about new plants!

Night Blooming Jasmine on Long Island

(image of Cestrum nocturnum courtesy of Logees.com)

Question:
Hopefully you can help me. I received a night blooming jasmine as a gift. It is currently in a small clay pot. It is doing quite well – I have new growth and blooms.
Living on LI – can I plant this in the ground – will it come back after a NY winter?
If I don’t put it into the ground, what do I do with it once the weather starts to cool off?
What is the care for this plant during the winter months?
Do I pinch after blooming?

Answer:
Night blooming jasmine (Cestrum nocturnum) is what we would consider a “tropical” up here in New York. It is an evergreen shrub, but only hardy through much milder winters down south and in the West Indies where the plant is indigenous. The plant sounds very well situated now so you do not need to change your routine anytime soon. If you have spent blossoms then you can deadhead them with pruners or scissors and remove them in order to redirect water and nutrients to the actively growing portions of the plant. I imagine you have it in a sunny spot and are keeping it well watered which is important as the plant is most active right now. In the fall, say late September or when the evening temps get down to the 60s, I would move it inside to as sunny a location as you can. You will continue to keep the soil moist and slowly cut back on your watering so that by winter you are allowing the soil to dry out a bit between watering. The plant will go through a dormancy period this winter so you will not expect tons of new growth or flowers, but it should certainly survive indoors over-winter. If you feel like you have to do some pruning I might hold off until next year once you have moved it back outside when the days are longer and nights are warmer again.

Caring for a Michelia figo

(Michelia figo image courtesy of floridata.com)

Question:
Quick question- I have a Michelia figo, not very big, in a 4" clay pot. I have it on a windowsill where it gets full blazing sun- do you think that's too much? It doesn't seem to be growing much and the leaves look ever so slightly yellowish. (I have kept it watered and fed). Thoughts?

Answer:
I love it when people ask me about a plant I don’t know! Excuse my snooping, but where did you get it?

According to Flora: A Gardener’s Encyclopedia (Timber Press, 2003) the genus Michelia includes about 45 species of mostly evergreen shrubs native to tropical and subtropical Asia. Named after an early eighteenth-century Italian botanist, Pietro Antonio Michele, Michelias are members of the Magnolia family (Magnoliaceae) and those amazingly beautiful and fragrant blossoms are supposed to bloom during summer. They grow best in fertile, well-drained soil and situated in full sun and sheltered from strong wind. Michelia figo is commonly called port-wine magnolia or banana shrub, again because of the rich fragrance, and in its native habitat it can grow to 15 feet tall.

It sounds to me like the sunny spot it is in was the right choice. Depending on when you got it and what the light conditions were like before, it might still be acclimating to its new environment. Luckily you bought it young and small and that is a good thing since younger plants are often more adaptable and can recuperate more quickly to new environments. Just last week I moved some tropical seedlings out to my front stoop and even though I lost a few leaves to scorch, they seem to be quite happy and holding up fine. If it is in a 4” pot then I am assuming you didn’t repot it when you bought it. I would probably do that. In fact I often repot new plants right away just to make sure I know they are then set up for success. Transplanting it into a slightly larger container, say 5-6” in diameter, and giving it some rich, fresh soil you can be a little more certain that it has both the nutrients and the drainage it requires. If the slight yellowing is any kind of nutrient deficiency the repotting should take care of that. Since this is a tropical shrub I would also do whatever I could to increase the humidity. Avoid any drafts from A/C as that can be a quick killer of humidity-loving tropicals. If you have the window open so it can get a little humidity from the outside I bet that would help. Then of course there is what I call “the saucer trick”. Place a layer of pebbles in the saucer so that excess water can collect in that “buffer zone” and evaporate to provide more humidity to the area right around the plant. Even if the soil is moist I might add a little water to my saucers just to make sure I’m keeping the humidity level increased. I’m not typically one that mists my plants, but if you do then an early morning misting before the hot midday sun might not be a bad thing. Lastly, you could incorporate a balance fertilizer into your watering regiment for the summer, but in the long run I would just rely on regular watering and transplanting again with fresh soil in a few years.

Hope this helps. If you get your Michelia figo to flower be sure and send a photo my way!

Houseplants in Nebraska

Question:

I live in Nebraska and have house plants. Lately, after watering them we can smell mold coming from the pots. Is there something I can do about it, I don't want to throw them away.

Answer:

If the soil in your houseplants containers is extremely stinky then you definitely want to take some action to right the situation since good potting soil and/or compost is usually quite odorless. Let me suggest a few things to try and hopefully you will not have to get rid of any of your houseplants.

A good thing to know right off the bat is that most houseplants require significantly less water in winter. Even though our homes are kept warm through the winter, the sunlight during the day is significantly less and our houseplants are simply not as active as they are during the summer months. Many houseplants we consider evergreen still go through a dormancy period in winter. With limited sunlight the plants are still photosynthesizing, converting sunlight into energy in the form of carbohydrates, and growing, but at a much slower rate. As a result, your plants water needs are not as great as they are during the summer when the plants are photosynthesizing and growing at a much faster rate. In winter I still try and water with some regularity but I definitely apply much less water. Each houseplant has different needs, but in general I am always advising people to water slightly less but with greater frequency instead of drowning your plants and waiting until they are bone dry to water them again. Even some plants, like succulents for example, I might water only once a month in the winter, compared to once or twice a week during the summer. Excess water that is applied to the soil and not taken up by the plant then sits and runs the risk of promoting rot of roots and soil in your containers. So, first of all, if you don’t already, consider watering with less volume in winter.

With that being said, let’s address your plants more specifically. Hopefully the plants are not that large because what I would recommend next is to carefully pull the plants from their containers and inspect the soil, roots, and containers. Create a work space for yourself because you may very well make a mess, and if possible do this during a cloudy day or at night so the roots do not run the risk of being burned by direct sunlight. What you want to find is soil that is not overly compacted or claylike. When slightly moist, a good potting soil you should be able to ball up in your hand and when you release it, it should fall apart pretty easily. What you do not want is soil that has broken down so much that it is either like clay or like pulverized dust. Next look at your roots. Healthy roots are usually white or light in color and firm, rotting roots are dark or black, squishy to the touch, and probably not very good smelling. If you have root rot take a sharp pair of pruners or scissors and get the rotten roots out of there; they’re of no help to the plant. Lastly, make sure your containers have adequate drainage holes in the bottom. All houseplants require containers with drainage holes, even if they are considered water loving plants.

I’m hoping that all you really have to do to right the situation is repot some of your houseplants. Spend the extra couple bucks on a name brand potting soil (Schultz, Miracle Gro, etc) because the soil structure will be better than generic bags of soil that inevitably seem to frustrate me. If your containers do not have drainage, switch them to containers that do. If you have succulents or plants that require maximum drainage, consider a layer of small stones or pebbles in the bottoms of your containers to create an additional buffer for excess water not used by the plant. Usually you want to repot in spring, but it sounds like the plants will benefit from being checked out as soon as you can find the time. Let me know how it goes and if you need further help. Good luck!

Growing Citrus Indoors in Rye, New York

Question:
I live in Rye, N.Y and I also have been having similar problems with many of my 2 dozen potted citrus. I have had most for 2-3 years and they have seemed healthy. Fought off citrus red mites last winter with horticultural oil and pre-treated them in September before bringing them into the house this year. They are in a sun room with ambient temps around 70 degrees. They get east and southeast sun for half of the day (when there has been sun). They are potted in 5 gallon pots with either a mix of citrus/cactus soil or Moisture-control potting soil mixed with orchid bark stuff. The pots have extra drainage holes and the plants are not allowed to sit in dishes with water.

They grew really well this summer with lots of flowers and fruit. The new leaves appeared chlorotic so I fed them as best I could with iron and minor elements as well as a general plant food (Ran out of the citrus foliar and citrus liquid I had brought from Florida several years ago.) They never really looked great, but.... I top-pruned them so they would fit in the house with the 2 dozen Rosa Sinensis I have and brought them in. I've since obtained citrus foliar feed (but can't spray while in the house) and some granular citrus food. I put about a teaspoon of this on them after bringing them in having read that citrus are "heavy feeders" and they looked kind of "pale".

They soon began dropping leaves which I assumed were the previous year's growth but the leaf drop continued and several plants began to get shriveled leaves which turned brown and the trees failed. No bugs, the soil smelled normal. I unpotted one of the "sick" plants (a Buddah's Hand) and found mostly roots, none circling the pot, no rotten roots or bugs in the soil. I cut away some of the larger roots and put the plant in a clean pot with the above mentioned soil mix and I'm waiting for something to happen.

So, basically I have had citrus trees with leaf drop of 1) Apparently healthy leaves; 2) Leaves that shrivel and brown around the edges before falling; 3) Branch tips that wilt and don't respond to watering (if previously dry).

Somehow I thought I had saved my "grove" last year after the mites, but I'm unable to fix their problems now. I'm attaching some pix with the hope that you can somehow advise me since what I read on your blog seemed entirely reasonable for Hibiscus and Citrus.

I would be eternally grateful if you could help me manage my indoor citrus.

Answer:
Thank you for writing. I can’t even imagine how nerve-racking it must have been to deal with the red mites given the amount of citrus you have potted up. I’m so glad you were able to control the situation. Let me share with you my knowledge of citrus, along with the aid of some literature here in our library, and hopefully I can provide some new information to help you.

Regarding the sunlight it sounds like the room has a strong enough exposure that your many citrus get the hours of direct sun that they need. I assume in summer you place them in an area with an equal amount of direct sun.

A constant temperature of 70 through the winter sounds good. Your citrus could probably even tolerate colder temperatures, into the 60’s or upper 50’s, but I understand that you still want to enjoy your sun room as well. The only other thing about the temperature, as reiterated in my research, is that you want to make the temperature transition as smooth as possible when moving the plants indoors or out. I assume the sun room gets warm during the summer, but in the fall if the room stays around 70 then I would move the plants in while it is still nearest to that temperature outside. Of course we also need to take into consideration the nighttime temps in the fall and spring as they can drop pretty low compared to daytime temps. I have seen people leave their citrus outside until it gets in the 60’s or below and then move them into an enclosed, warmer 70 degree room and that can certainly lead to some shock and leaf drop.

Certainly the citrus and/or cactus soil is great because it has such excellent drainage. I would probably add some quality compost to it as well to increase the nutrient value and water holding capacity. I am curious to know more about how the plants in the moisture control and/or orchid bark mix are holding up. Both of those media can hold moisture for long periods of time without drying out and I was taught that all citrus enjoy being in soil that is allowed to dry out a little between watering. I’m sure the extra drainage holes you added make all the difference.

Citrus are heavy feeders, but you will want to concentrate more on when they are feeding most heavily. During the warmer months when the days are longest and the temperature and humidity is at optimal levels your citrus are going to be most active. In combination with the fact that they are all containerized, this means that fertilizing is most important through the spring and summer. Most citrus fertilizers have a higher first and third number, which means higher doses of nitrogen and potash compared to phosphorous. The nitrogen is important for the green of the plant, the development of foliage for photosynthesis. Potash is important on the cellular level because it aids the overall structural health of the plant. During the summer I would fertilize regularly every two weeks with a citrus fertilizer or another fertilizer as long as it is high in nitrogen and potash. If your local garden center does not carry a product specific enough I was able to find a number of adequate fertilizers for sale online. This time of year, since the plants are inside and still getting ample light, I might still fertilize but definitely less than during the summer. Since chlorotic foliage is an issue I might switch to a foliage fertilizer, with a high nitrogen content and lower phosphorous and potash, and apply lightly and sparingly through the winter. Usually I tell people not to fertilize in the winter at all but in your case it might help. Even though your citrus are evergreen they are still in more of a resting period this time of year. Over-fertilizing in the winter, when the plant is not active enough to take it all up, you can run the risk of adding too many soluble salts to the soil and that can inhibit nutrient uptake even if nutrients are present in the soil. I doubt you have, but if you fear you have over-fertilized, you do have the option of flushing the soil with a heavy watering and leaching out excess salts.

Aside from the fertilizing, the only other issue that seems most pressing that I haven’t mentioned is the humidity. Dry winter air is brutal on our indoor plants so increasing humidity in the room is the first thing that came to my mind when you mentioned shriveling leaves and wilting tips. I have oversized glazed or plastic saucers with gravel below all my indoor plants. Excess water that collects in the gravel “buffer zone” evaporates in the immediate area around the plant and should help those dry and wilting tips. Some times I will even put a little water solely in the saucer if I know the soil is moist enough. This winter I went a step further and finally bought a humidifier and all of my plants look so much better. Increased humidity will not only increase the health of the new growth and the older growth to hold on, but it will also help combat pests like the red mites who thrive in drier conditions. I think even a spray bottle with a fine mist would be a help during these dry months if that isn’t already part of your routine.

I hope this information helps give you some new insight and is not too repetitious to what you have already read or know yourself. If you have more questions send them my way or feel free to call me in the office during the work day to discuss. Good luck.

Notes from Around Town: Ford Foundation Atrium

As fall and winter finally approaches, and as we adjust to our winter routine of spending less and less time outside, I wanted to share with you a special interior green space here in the city we can all enjoy. Below are pictures from the Ford Foundation Atrium, which is located between 42nd and 43rd Streets just west of First Avenue. Built from 1963-67, this interior garden space is one of the most popular green atriums here in New York City, and rightfully so. When you enter this green oasis you can't help be amazed by the tropical plants of all shapes and sizes that stand before you. As you follow the choreography of the pathways you find yourself eventually surrounded by these trees and shrubs, taking in the good air, and at peace thanks to the soft sound of the water feature in the center. The atrium is open to the public from 10-4 on business days and if you have never been, it is a visit that you should treat yourself to very soon. Even yesterday, on such a dreary day here in the city, my coworker and I couldn't help but feel inspired and energized after our trip through the atrium.
Different kinds of Ficus trees that have been there for years are now well established and reaching up 20+ feet into the vaulted ceiling that goes up the entire height of the building.
Below the larger trees the sloped beds are loaded with tropical shrubs like Schefflera arboricola with it's rounded palmately compound leaves, and groundcovers like Trandescantia with striking purple on the undersides of their silver-striped leaves, just to name a few. Variegated plants are incorporated too, like the arrowhead vine (Syngonium podophyllum) to provide additional texture to the planting beds on a year-round basis. With enough plants to maintain decent humidity in the atrium there were even a number of different ferns that I was thrilled to come across.
As we strolled through my coworker and I had to marvel at how brilliantly the atrium was laid out so that it was visible and enjoyable to all those in the offices up above. A man and woman were sitting on one of the paths having an afternoon debriefing and certainly we thought they had found the perfect setting for their little meeting.
In addition to all the levels and layers on the ground floor there is a mezzanine that had large trees and shrubs in it, as well as many hanging plants that cascade down to welcome you when you enter from 43rd Street.
And even though most of the plants in the atrium are tropical plants known for their foliage, I was able to find a few wonderful flowers to educate my colleague about. Above is a tropical shrub or tree botanically known as a Calliandra. Not surprisingly the common name of this tropical shrub is known as either powderpuff or flame bush. There were also camellias in bud and a few already putting out their multi-petaled winter blossoms. Down by the water feature in the center I found a gardenia that still had a number of their intensely fragrant flowers on it, and I tell you, I could stand there and smell the gardenias all day they are so amazing. So, next time you are over on the east side around 42nd or 43rd Street, treat yourself to a walk through the Ford Foundation Atrium. I am sure you will be pleasantly surprised. And lastly, as always, keep in touch with HSNY and become a member as I hope to lead a tour or two of the atrium, and perhaps others, in the upcoming months.

How to Care for a Bromeliad?

(Neoregelia is a member of the Bromeliaceae family that we grow here at HSNY Headquarters)

Question:
I have a Bromelia plant and would like any care instructions you could provide. Do I water it at the top of the leaves and let it funnel down as I have been told. The water seems to accumulate and I fear will rot the leaves. How close to the leaves should the dirt go? It does not get direct sunlight is that okay? The flower fell off, will it grow another?

Answer:
Bromelias and other members of the Bromeliaceae family, collectively called bromeliads, can be pretty easy to care for. As you know, the leaves emerge from a central rosette and create a bit of a cup. It is true that you want to water your bromeliad by pouring water into that cup. In their natural habitat, bromeliads grow at elevations up to 6,000 feet and are either epiphytic (meaning they grow on other plants) or they are terrestrial (meaning they grow in the ground). For this reason, they take in the majority of their water through the “cup” which serves as a water reservoir. During the summer months when the plant is most active you will see that the center will dry out and will need to be refilled frequently. You always want to keep some water in the cup, but during the winter months when the plant is less active you will realize it does not take it up nearly as quickly. Do not worry about rotting the leaves, they are tough. As for the mix it is potted in, you can water that occasionally as well, maybe once a week or so. The mix is more to anchor the plant in place, but if saturated, that can rot the base of the plant and you want to avoid that. Bromeliads love humidity so you may choose to have a layer of stones in your saucer so that excess water can evaporate immediately around the plant without the plant actually sitting in water. As far as the soil level, in some cases the potting mix is right up to where the plant flares out, in other cases there might be a little more of a stalk. This can vary as long as the plant is properly anchored in place and the mix drains freely. If it does not get direct sunlight, at least provide it with as much bright light as you can. I do not recommend bromeliads for shady situations. Finally, regarding the flower, you are going to continue to grow your bromeliad and you are going to watch out for a new growth from the base. A new side-shoot should eventually emerge, and grow into a tall plant of its own. Eventually this side-shoot, called a “pup” will grow to be large enough that it will produce another flower.

Plant ID: Mandevilla x amoena

Question:

My friend was given this plant but is unsure of what it is called.
Can you please tell me what it is and how to overwinter it here in Michigan?

Answer:

The plant your friend was given is called a mandevilla (Mandevilla x amoena). Native to Brazil, this climbing vine is a hybridized cross of Mandevilla amabilis and Mendevilla spendens. Because of its tropical origin, the plant cannot tolerate winter temperatures below 55 or 60 degrees. Therefore, the only option to successfully overwinter the plant in Michigan is to bring it inside. Keep it in an area of bright light, but be careful that it is not too close to a hot, dry radiator. Continue to water it as you have been, and as winter comes you can ease up and water more sparingly. When overwintering tropicals inside, I like to use below the pot a glazed saucer with a layer of stones or pebbles in it. This way excess water that is in the saucer can evaporate and provide a little extra humidity during the dry winter months without running the risk of rotting the roots of the plant. You can also mist the foliage if you feel the plant is getting too dry. A reference book I have says to cut the plant back to keep it bushy and promote next years flower, but I might recommend against that. I had one in my home years ago that I cut back hard this time of year and it seemed like forever before it got to be as full as it was. I prefer to stake it well and let it continue to climb. Through the winter the vine should continue to grow and put out new foliage, but do not expect much in the way of flowers until next summer. When you move it outside next spring check on the roots as it may be ready to be repotted.

Reference: Indoor Plants: The Essential Guide to Choosing and Caring for Houseplants by Jane Courtier and Graham Clarke, Reader's Digest, 1997.

Hibiscus Tree in Westchester County

(photo of Hibiscus rosa-sinensis I took down in the Flower District on 28th Street)

Question:
I received a gift of a potted hibiscus "tree." Can you tell me where I can find info to care for it? It is on my deck (Westchester County NY). What do I do with it in winter?

Answer:
Thank you for writing. By describing it as a potted “tree” I am going to go ahead and assume that you were given a tropical form of Hibiscus. In a post I wrote back on June 18th I describe the different kinds of hibiscus. On the archive menu on the right side of the page, pull down the menu for June and select the post entitled “Hibiscus in Nassau County”.

What you have been given is a tropical hibiscus. The botanical name is Hibiscus rosa-sinensis. By doing internet searches using the full botanical name you should be able to find reliable websites that give care instructions. If not, here are the basics of what you need to know.

Your hibiscus loves full sun and will flower best if you can keep it in an area with as much sun as possible. Because it has been trained as a “tree” it also requires a fair amount of water. I would water daily or every other day, making sure that the soil is kept moist all the time. Because “tree form” hibiscus have been trained so meticulously, you may find that they benefit from being misted with a spray bottle as well. The only thing about misting your hibiscus is that you want to do this early in the morning so that whatever water is on the foliage evaporates before the hot midday sun. If water is sitting on the leaves and the hot sun comes out it can actually burn holes right through the foliage. As far as winter, you will have to bring the plant inside if you wish to keep it alive through the colder months; it will not survive the freezing outside temperatures. Before threat of frost, move the tree inside to an area that has as much sun as you can provide. Keep the soil moist, and as winter comes, ease up on the watering so that the plant gets a chance to dry out between waterings. Even though it will hold onto it’s leaves, your hibiscus will go into a kind of resting period through the winter. As the days get shorter and there is less light naturally, you might experience the tree dropping some of it’s interior leaves. This is natural shedding to help the plant get through the darker winters. While the plant is inside you should expect to get more green foliage growth, but do not expect the plant to flower again until next summer when it goes outside again. You can move it back outside after the last fear of frost, and at that time you will want to consider fertilizing it through next spring and summer.

An Ongoing Discussion on Citrus Trees in NYC

Question:
The problem I encounter is with my lemon tree. I have this tree for 4 yrs and it has always been a happy tree, or at least as happy as a citrus tree can be on the 34th floor of a building in Manhattan - flowered, grew and constantly made fruit. Suddenly, approximately 2 weeks ago, the leaf's central vein and parts of the leaf started turning yellow [I have attached 2 pictures in pdf format]. I repotted the tree in soil suggested as best for cacti and citrus and administered water with Miracle Gro and extra mg sulfate added, thinking that maybe the yellowing was due to mineral deficiency. But now I have my doubts - none of the pictures I have seen on line describing nitrogen, Mn, Fe or Zn deficiency seem to result in this leaf pattern. Could you please suggest what this can be and how I can fix it? Or direct me to someone who can help me out with this?

I, Alex Feleppa, then followed up by asking a few more questions:

What time of year did you repot your tree?
I HAVE REPOTTED THE TREE 10 DAYS AGO, ABOUT 7-10 DAYS AFTER I HAVE FIRST OBSERVED THE LEAF PROBLEM. THERE ARE NO IMPROVEMENTS AS YET, AND THIS MORNING I SAW THE FIRST LEAF DROP.

The pot that your tree was repotted into, does it have adequate drainage? Do you fertilize the tree regularly? And finally, when did you add the Miracle Gro and Mg sulfate?
YES, IT IS A CERAMIC POT WITH A DRAINAGE HOLE AT THE BOTTOM.
NO, I HAVE NOT FERTILIZED THE TREE FOR ABOUT A YEAR.
I ADDED THEM ABOUT 10DAYS AGO AFTER REPOTTING THE TREE. I HAVE WATERED THE TREE TWICE SINCE, [ABOUT 4 DAYS AGO AND TODAY] BOTH TIMES ADDING A LITTLE MIRACLE GRO TO THE WATER [NO MAGNESIUM SULFATE THIS TIME].

Even though the problem has come about quickly, your tree looks rather large so it might take a little while for the tree to bounce back. Larger plants, and especially trees, often work on a schedule that is slower than our patience allows. Perhaps there was some stress in the last year that the tree is finally showing.

It sounds like you are doing all the right things. I just found this paragraph on the University of Florida's website:

"Yellow vein chlorosis may be attributed to the girdling of individual branches, tree trunks or roots due to a number of factors including water damage, Phytophthora foot rot, root rot, ant damage, or physical damage by equipment. Yellow vein chlorosis may also occur on twigs and branches due to cool weather in the fall and winter due to lack of nitrogen uptake from the soil. In leaves showing yellow vein chlorosis, the midribs and lateral veins and a narrow band of leaf tissue bordering them become yellow while the rest of the leaf remains green."

Because lemon trees can grow so quickly, my gut instinct is that it needed to be repotted. And by doing that I hope you already solved a problem. When you repotted it, if you had noticed lots of rotting, mushy roots then perhaps we might consider some of the diseases listed above. Since that didn't seem to be the case at all I think it is safe to rule out diseases as the issue.

In addition to the roots wanting more room (which you have now supplied), they also need fertilizer. A regular fertilizing with Miracle-Gro during the summer months should supply the tree with enough nitrogen and micronutrients. If you have not been doing that in previous years then the soil might have gotten rather depleted over time.

If you have lost some leaves I consider that a natural reaction to being repotted. The tree went through some stress when it was repotted, so it may lose a few leaves while it acclimates to the new pot. That is normal. The important thing now is to keep watering it and caring for it as you always have. It's when we panic and change our agenda drastically that plants can decline even more. Water it as you have been. Follow the fertilizer instructions and ease up on that in the fall. Obviously keep the tree in as much sun as possible. Lastly, keep me posted and let me know if the yellow chlorosis spreads to more leaves.

Another Plant ID: Curcuma alismatifolia

Question:
Would you be able to help in identifying the flower in the attached picture?

Answer:

The flower in the picture that you sent to me looks very much like a tropical ginger. Botanically the plant is known as Curcuma alismatifolia, or commonly known as a Siam tulip. I refer to this as a tropical because it would not survive the cold winters here in New York. It is cold hardy in Zones 8-11 which means it might survive the winter in South Carolina, Georgia, or further south into Central America. In full sun Curcuma alismatifolia can grow to 2’ tall and flowers this time of year. It may be a certain cultivar, but I am not able to say which one based on the photograph. Usually you can find this plant for sale in pink, white, or magenta. If you took this picture in the northeast I would believe that someone grew it to be more of an annual. It provides great height and color in a summer garden, not to mention very popular as a cut flower, but would then have to be repurchased and replanted next spring.