Friday, August 31, 2007

"Tree Pants" Reviewed in the New York Times

Peter Coffin, Untitled (Tree Pants, Fall), 2007

The current art exhibit on display at The Horticultural Society of New York, "Tree Pants" by Peter Coffin, curated by Jodie Vicenta Jacobson, has been reviewed in today's New York Times by Roberta Smith. To read the review simply click on the link here and scroll down the page until you see the title "Tree Pants". Then be sure and come see the exhibit yourself at HSNY's headquarters at 148 West 37th Street, 13th Floor, Monday through Friday 10am-6pm. But be sure to hurry! This exhibit will only be up on display for another week, closing on September 7th. Hope to see you soon.

Thursday, August 30, 2007

More Houseplant Mushrooms

Question:
I seem to have mushrooms in my hibiscus, and I can't figure out where they came from, or how to get rid of them. The hibiscus is strictly an indoor plant, and has been for about 4 or
5 years (ever since it grew too big to move outdoors in the summer). It's been in the same pot - and the same soil - at least since then. A few weeks ago, I noticed some small yellow mushrooms growing in clusters in the soil at the base of the pot. They grow fast, and no matter how often I pull them out, they keep coming back. I know it's been very humid lately, and I do try to let the soil dry out between waterings, but it doesn't seem to help. Since the plant lives indoors, I'm not sure where they came from - no other plants in the house seem to have them, fortunately - and I'm at a loss as to how to permanently get rid of them. Any suggestions you have would be greatly appreciated! It's a lovely old plant, and I'd like to keep it around for a bit longer.

Answer:

Believe it or not, I have actually gotten this question before. Back in July a woman wrote, describing similiar mushrooms growing at the base of a houseplant she too had had for a number of years. You can click on a link to that entry here.

The important thing for you to know is that these mushrooms are not going to kill your hibiscus. They do promote the further degradation of your soil, and in a container that is not the greatest thing, but the mushroom spores themselves will not harm the plant. As you know, however, they will continue to spread and put up mushrooms. I do not know if there is a fungicide on the market that is used to combat these mushrooms in particular. Taking more of a naturalistic approach, I would recommend repotting your hibiscus. If it is 4-5 years old and has never been repotted then the plant will benefit from fresh soil that has better soil structure and more nutrient value. Given the mushroom situation, try and remove as much of the old soil as possible before applying the fresh soil. Repot your hibiscus into a larger container that is a couple inches greater in diameter. It is best to repot hibiscus in the spring, but if you feel the need to do it now I do not think that is going to shock the plant too much. When repotting, do your best not to expose the roots to direct sun or extremely hot temperatures as this may stress the plant, and we obviously want to try and avoid that. Good luck and let me know if you need further help.

Monday, August 27, 2007

Plant ID: Hosta 'Sea Octopus'

A coworker and good friend recently came to me with this photograph that she took in the rock garden at the New York Botanical Garden just about two weeks ago. She was taken aback by the tall striking flower of this certain Hosta cultivar and asked me if I might be able to identify it. Luckily I am good friends with a number of curators and gardeners up at NYBG and I was able to track down an answer. Thanks to Jody Payne, curator of the Rock Garden and fellow alum of the School for Professional Horticulture, the Hosta in question was identified as a cultivar named 'Sea Octopus'. As she went on to add, there is also a little variegated variety that is really nice called 'Crested Surf' which has the same tall purple flowers. For information on where to buy this kind of Hosta, you can email me directly at the email above and I can supply you with that information.

Wednesday, August 22, 2007

Plant ID: Pachypodium sp.





Question:
I was given this cactus as a present from a supply house here in New York that no longer exists. My plant consists of four stalks, the tallest of which is about 40" tall from the top of the 11" diameter clay pot in which it is planted. In their heyday, each stalk put out a grand splay of green leaves at their top which would replace itself except for a slow period in the winter.
I water the plant once every three weeks by immersing the pot but don't know whether I should be wetting the leaves and stalks at the same time. I have had good reaction to Miracle Grow once or twice a year. The plant sits on the window sill of a New York City apartment and gets direct sunlight for perhaps 2 or 3 hours a day. I have not seen any evidence of bugs or other infestation but have sprayed it on occasion with Safer Soap on the recommendation of my local florist. During the last year it has passed through several phases of losing almost all its leaves, which eventually come back but not in the solid, full spray of the past. The tallest stalk now puts out leaves but they almost all start to shrivel and darken before they have fully grown.
So, doctor, that is my problem. What am I doing wrong? What can I do to bring it back to its former great self?

Answer:
Your cactus belongs to the genus Pachypodium. Pachypodiums are native to southern Africa and Madagascar. These cactus-like deciduous succulents are used to much warmer and dryer climates and should not be subject to temperatures below 50º Fahrenheit. In total there are about 17 recorded species of Pachypodium. Even though I cannot identify the species with 100% confidence, I might guess that you own the species Pachypodium lamerei. Pachypodium lamerei I have seen written up as a viable houseplant in the U.S. since it does not get nearly as large as some of the other species. A good ID tool for these plants is the flower (color, size, fragrance, etc), so if you have ever seen it flower that might help us identify your plant more specifically.

Regarding caring for your Pachypodium, they do prefer full sun and a fertile soil with maximum drainage. They can be watered with regularity during the active growing season from late spring through summer. Since you have plenty of new growth in the form of those small side shoots I would say your watering every three weeks is fine. As the saying goes, “if it ain’t broke don’t fix it”. However, since I know that this genus of plants goes dormant in the winter, I think you should cut back gradually on the water so that you are applying less or none in winter. As the days shorten and there is less sunlight for photosynthesis, the plant will begin to slow down. Perhaps water only once in November, once in December, and once in January. For late January and February do not water at all. You would then begin watering again, starting in March with smaller amounts and eventually getting back to the full submerging by the end of April or May. As for the Miracle-Gro, I would only apply it once a month when you water during the active growing months from June to September. It is best to repot in springtime while the plant is resting and before it becomes very active again. Schultz (I believe) actually has a soil mix that they advertise as being best for cactus and succulents. The label is quite clear, and I have found it in garden shops of all shapes and sizes around the city. The soil itself I have had good success with. I have even used regular potting soil with sand mixed in, but sand alone is not always as easy to come by in the city.

Finally, let’s revisit some of the issues you have noticed recently. The pinched deformities to the leaves on the tallest stalk are some kind of insect damage. To combat this, I believe that the insecticidal soap is your best bet. Safer is a popular company and I can stand behind their whole line of insecticidal soaps ready to use in spray bottles. You might want to treat a single leaf before applying the spray to the entire stalk, but the leaves seem sturdy and glossy enough that they should hold up just fine. Looking at the brown and black leaves, I would guess that those might be caused by a nutrient deficiency. As we have already discussed, since you have not repotted the plant in the four years you have had it, I would recommend changing out the soil. Fresh soil should allow for adequate nutrients and drainage for the plant. It seems as though the size of the container still allows for ample growing room so I think you can use the same pot when repotting. As far as the best order to control these issues, I would try and treat the deformed leaves and pest issue now and wait until spring for the repotting.

Tuesday, August 21, 2007

Plant ID: Datura sp.



Question:
I recently found this plant growing on the front of my friend's home, very close to the shrubbery. Can you help with its identification? It seems to have sprung up from out of nowhere and is growing quite rapidly. Neither my friend nor I certainly didn't plant it. A neighbor a few homes down has a small island of these growing in front of his shrubs, as well. The location is Peekskill, NY (Westchester County). The first picture taken shows the leaf of a newly-growing plant. This plant is about 1.5 feet in height, and leaf itself is approximately 8" long. The second picture shows one of the flowers that bloom on the plant. The flowers are white or cream in color, and approximately 6" long. The third picture shows, well, I'm not quite certain what one would call them except spiked balls. They're approximately 1.5"-2.0" in diameter and are found throughout the plant on its stalk.
Answer:
The plant you are trying to identify is a kind of Datura. If I had to guess as to the species I would say that you have Datura inoxia, commonly called angel’s trumpet or downy thorn apple. Native to the much warmer climate of Central America, Daturas are considered to be annuals up here in the northeast. As you have observed they do grow very quickly during our hot summer months. I was walking around my own neighborhood of Astoria, Queens, over the weekend and had seen a few which had obviously seeded themselves around. The prickly growth, or “thorny apple”, is their seed heads and removing them helps prevent the plant from spreading and sowing its own seeds. Even though the plants can get to 3’ or 4’ tall, I would not expect the plants or seeds to survive the winter up where you are located. I would certainly guess that the one in your yard came from your neighbors stand of them. Daturas are known to be quite toxic, and if ingested they can lead to long horrible spells of hallucinations, but the plant will not harm you if you simply want to remove it. If you need any further information, do not hesitate to call.

Thursday, August 16, 2007

New HSNY plantings at the Seventh Regiment Armory

(New HSNY plantings on the south side of the Seventh Regiment Armory, 66th Street between Park Avenue and Lexington Avenue)

(New HSNY plantings on the north side of the Seventh Regiment Armory, 67th Street between Park Avenue and Lexington Avenue)

If you live or travel through the Upper East Side then you are most likely familiar with the Seventh Regiment Armory which goes from Park Avenue to Lexington Avenue between 66th and 67th streets. Constructed from 1877 to 1881, the Seventh Regiment Armory is an unbelievable cultural and historic landmark located right here in Manhattan. As part of the tremendous renovation effort organized by the Seventh Regiment Armory Conservancy, The Horticultural Society of New York was commissioned to renovate the exterior spaces on 66th and 67th Streets from Park Avenue to Lexington Avenue. Before the renovation took place I visited the site with James Jiler, fellow HSNY staff member and Director of the Riker's Island Greenhouse program. We looked at the then-desolate space full of rat holes and inhibiting roots from the maples and the London plane-trees and I knew our GreenTeam had their work cut out for them. Walking by yesterday I couldn't believe the change of scenery and how the new plantings seemed to give new life to this part of the local community. With many different hollies planted as structural elements as well as many different hosta and impatiens used to complete the greening of the space, I would like to publicly congratulate my fellow staff members and members of the GreenTeam on a job very well done. And for those of you who are HSNY members, I want to thank you for your support and for making possible these many community outreach programs that help to make New York City a greener and better place to live. Are you an HSNY member?

Wednesday, August 8, 2007

Deadhead Verbascum?

(photo of Verbascum thapsus)

A woman called the other day to ask a question about her Verbascum. She has a number of Verbascum that are now in their third year in her garden. They have bloomed prolifically every year and she has been very happy with them. The question that she asked of me had to do with the flower spikes that have now passed bloom. Is it ok to deadhead Verbascum or is it better to leave the flower spike on the plant?

This is a great question, and there are different ways of answering it.

Aaron’s rod (Verbascum thapsus) is a plant I enjoy in the garden because of the large rosette of silver, felted leaves and the dramatic yellow flower spike. As I learned more about the plant, specifically its drought tolerance and ability to adapt to a wide range of soils, it only became more attractive in my mind. The one drawback however is that this Verbascum is considered to be a true biennial. A biennial is a plant that goes through its entire life cycle in two years. The first year Verbascum typically goes through a period of vegetative growth, growing that large rosette of foliage. It is then in its second year that the plant puts on its reproductive growth, the tall flower spike. Because Verbascum may die after flowering in its second year, I was taught to recommend leaving the flower spike on the plant to increase the chances of the plant self-seeding. The straight species of Verbascum thapsus are known to self-seed quite readily throughout the garden and seedlings can be transplanted to desired spots or easily removed if that is your wish. There is another species, Verbascum phoeniceum, commonly called purple mullein, and it too is considered to be a freely self-seeding biennial.

Verbascum hybrids, on the other hand, are quite a different plant. Once it was explained to me that this woman’s plants are blooming every year I knew that they were most likely not a straight species, but more likely some of the newer hybrids that growers are developing. For Verbascum hybrids, deadheading is preferred for a couple of reasons. For many hybrids removing the faded flower spike and preventing the seeds from being dispersed works to trick the plant into behaving more like a perennial and encourages it to come back year after year. The second reason to deadhead your hybrids is because regular deadheading helps promote the plant to produce new side shoots from the main parent plant. Next spring you may be able to carefully remove the small side shoots, or “pups”, as long as they have ample foliage and roots and transplant them to space where they can grow on their own. Therefore, to answer the question, if you know it to be a straight species, I would not deadhead it if you want it to seed itself in your garden. If you know your Verbascum to be a newer hybrid with a clever named cultivar (‘Helen Johnson’, ‘Raspberry Ripple’, etc.), then go ahead and deadhead it so that it produces new pups that you can hopefully then divide and transplant in the spring.

Squash Problems in Harlem

Question:
Here is a picture of the mysterious disease on our squash plants. One whole bed of squash has perished - the spots have moved on to a (nonadjacent) bed of zucchini - I fear for their safety. Can you please tell me what you think is going on here?Question:

Here's another picture if you can help figure it out. Some of our cucumbers are growing weird and lumpy... might just be random but if you have any ideas I'd love to hear them!

Answers:
As far as the squash, I think the situation is a fungal disease called powdery mildew. It occurs when there is not adequate air circulation to the garden, and it happens a lot throughout NYC. When there is not a lot of fresh air flow in the area and then lots of watering the leaves and stems can get covered with this white film. When the leaves are covered enough the plant cannot photosynthesize and the leaves die. In the extreme cases, if all the foliage gets affected then the entire plant can die as a result. There is a homemade remedy that people swear by. What you do is mix into a gallon of water two tablespoons of baking soda and a little dish soap (Dawn, Palmolive, etc.), just a drop to make the mix more viscous. Use this mix as a foliar spray and try and cover as much of the affected leaves as possible. Do this early in the morning when it is cooler and before the hot midday sun is out. If there are leaves that are really bad, just go ahead and prune and remove them to the garbage. In addition, try and increase the air flow as much as you can, removing any weeds or leaf debris that might be at the base of the plants.

As far as the misshapen squash, I am less sure as to why they are coming out looking so funny. It could have to do with the amount of water and/or the watering schedule you have the plants on. I suppose if you water heavily and then the plants go dry between watering then you can end up with some “lumpy” veggies. In addition, the rain storms we have had this summer have delivered so much water in such short periods of time, those mixed with hot dry periods in between might bring about some oddly shaped vegetables. If you water your plants with the same quantity of water and the same regularity throughout the week then you may end up with more “normal” looking vegetables. But I am sure even though they may look a little funny they are still perfectly healthy and worthy of being eaten. Think about how “perfect” the vegetables in a supermarket look – that is because farmers have their crops on a set schedule getting watered the right amount every day. For you and I who grow veggies in our own gardens they take on different shapes – that is most likely because the amount of water and how often we water can vary more. Another thought is that if the plants are battling with powdery mildew that may be affecting how efficiently the plants produce squash. My final thought has to with the presence, or lack thereof, of pollinators. According to Rodale's Garden Answers here in our library, misshapen fruit may be due to poor pollination during hot weather. There has been much talk about bee populations suffering in NYC and this may be a visible sign of that. If you do not see many bees in your garden then there is actually a way of pollinating your crops by hand and I can easily pass that information along to you.

For both of these questions I should say that there is a mosaic virus that can affect squash foliage and fruit, but none of the symptoms you have describes sound like this extreme of a problem.

Tuesday, August 7, 2007

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.

Friday, August 3, 2007

My Dracaena is Too Tall!

I often get calls from people that have corn plants (Dracaena fragrans 'Massangeana') or dragon trees (Dracaena marginata) that have gotten too tall for their apartments. Because they have grown these plants for so long and have become attached, they do not want to simply throw the plant out and start over, and I understand that completely. Therefore, I am most often asked is there a way to cut off the top of the plant and have it establish roots to be replanted?

The answer is there are a few ways of propagating a new plant from an overgrown parent plant. The first is a method called air-layering. This is a practice I learned in horticulture school designed to grow new roots on the existing stalk or bark of the parent plant before you severe it and place it in a new container. When air-layering, you begin by making an incision in the main stalk at an angle and inserting in the incision moistened sphagnum moss. In some cases, depending on the plant species, adding a rooting hormone is recommended as well. Then the cut and the sphagnum moss must be wrapped in plastic or cellophane so that it is kept constantly and evenly moist. Once roots have established from the initial wound, then the plant can be cut below that point and planted in a new container to eventually grow into its own. This process can take a number of weeks for sufficient root growth, but you can be certain that the section of plant will survive when you then remove it from the parent plant and plant it on its own. The drawback to air-layering is that you have to have a bandaged plant in your home that may not be so attractive. The other drawback is that this process takes some time and I must be perfectly honest and say that most of the people I deal with admit that they do not have the patience to attempt air-layering.

With that being said, there is another option for propagating a Dracaena from the parent plant. This alternative method is to propagate by stem cuttings. Granted it might not be as reliable as air-layering, but this anyone can do, and chances are you will still be able to continue growing the plant you have come to love. Here are a few pictures to help you through the process. This exercise I am doing here in the office as an example and I will keep you posted as to the development of new roots as they happen over time.

For this exercise, you will need a bag or regular peat moss, or a soil-less mix of ¾ peat moss and ¼ vermiculite. You will also want a plastic pot and saucer to place your cuttings in as plastic retains moisture for longer than terra cotta. If the peat moss or soil-less mix is dry, be sure to moisten it before you begin.
First locate on the parent plant a length of stem and leaves that is 4”-6” in length.For the best chance of root development and the plants survival, you need the cuttings to have some foliage so that the plant can continue to photosynthesize once it has been cut. With a sharp knife, severe this top portion of foliage and stem at a slight angle and separate it from the parent plant. For dragon trees (Draecaena marginata) some books suggest letting the cuttings sit for 24 hours, but for corn plants (Dracaena fragrans ‘Massangeana’) do not let the cuttings sit and dry out. I should say that this is also best done in the spring or summer when the plant is actively growing. Now place your cutting in your container of peat moss or soil-less mix. Remember that you need a long enough cutting that you can anchor it in the new pot with at least an inch of the stem submerged in the moist substrate. In addition, you may choose to remove or cut back a few leaves as well. Because the parent plant has many established roots, it can have an equally large amount of foliage; this is what horticulturists call the root-to-shoot ratio. Since you have removed the roots, you must pare down the foliage because this plant will have to essentially start over from scratch. If the plant is photosynthesizing like crazy and there are no roots to balance the flow of nutrients, then the plant can go into major stress and die. In addition, if you have an option, take your cuttings from the smaller shoots, as younger tissue often has better and quicker recuperative potential. Keep your cutting in the soilless mix and keep it evenly moist, watering it a few times each week. On the flip side, do not keep the mix sopping and saturated because you do not want to run the risk of rotting the cutting and losing the plant once you have come this far. As you would with any plant, keep the cutting in a spot with bright, indirect light and good air circulation. After 8-10 weeks your cutting should establish new roots and begin to live as a plant of it’s own. Once the cutting and roots have outgrown the container, repot it in a larger container in the spring.

Wednesday, August 1, 2007

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.