Saturday, March 31, 2007

Repotting your orchids in spring

This weekend I repotted a few new orchids and I thought I would show you how I did it. They were a couple of mature orchids, two Cattleya hybrids and a Brassavola hybrid, not yet in flower. I did also buy a Doritaenopsis hybrid in flower, but I will hold off on repotting that until after it has flowered. I do not want to shock the plant while it is putting out such a tremendous flower, not to mention I do not want to run the risk of accidentally breaking off any buds. For the others, however, I know that spring is a good time for them to be repotted, and I could tell that they were pretty packed into the plastic pots in which I received them. In general, repotting newly purchased plants is a good idea because then you can be sure that they are well situated in the appropriate mix in their new home. Here is a quick guide to repotting your new orchid(s).

The supplies you will need are: your new orchid, additional long fibered sphagnum moss or epiphytic bark mixture (depending on what your orchid is being raised in now), a container with good drainage the same size or 1” larger than the plastic growers pot you bought it in, a slightly oversized saucer, a bag of small pebbles or decorative gravel, and an ample work space with a faucet where you can make a decent mess. You will be using room temperature water (70-72°) and plenty of paper towel. Here you can see I set up shop in my kitchen sink with some extra space cleaned off on the counter.

Step one: Prepping your work area. Place your sphagnum moss in a container or colander and soak it thoroughly. Submerge and soak your terra cotta pot for a few minutes to make sure it is clean and saturated as well.

Step two: Cleaning and teasing your orchid. This is the part that makes most amateur growers most worried, but don’t be. You are going to have to touch and handle the plant roots, and some may break off, but you must realize that in the long run you are going to be making your new orchids very happy for their new home. Cut and remove the plastic pot. Now carefully tease out and loosen as many roots as you can. If the roots seem dry, do not be afraid to run some water over them to help make them more limber. Epiphytic orchids, those that grow in or on other plants, have roots with an outer tissue called velamen. Velamen helps the roots retain more moisture for longer periods of time, as well as helping protect against the suns rays. Once wet they are much easier to move and bend. Take your time to really tease out as many roots as you can, removing deteriorated moss, dead roots, and styrofoam. Remember that roots prefer to grow out and down, not necessarily in circles bound in a crowded plastic container.

Step three: Potting up. Go ahead and place a handful of moss in the bottom of your soaked, clean terra cotta pot. Squeeze the moss with your hands so that it is moist, but not soaking wet. Take another handful and work it in underneath the plant where you removed old moss, Styrofoam, etc. Like with terrestrial plantings you want to avoid leaving large air pockets in the container when you are done. With some moss in the pot and some cupped underneath your orchid, place the plant in the terra cotta pot. Push the roots down deep into the pot and begin to fill in with additional moist moss. Again, do not be afraid if it takes a little force to pack in all the roots and moss so that they are tight in the pot. An orchid expert and good friend of mine also passed on the tip once of twisting the plant as you place it in the pot. This helps you get the roots down deep into the container to properly anchor the plant in the sphagnum moss. Continue to fill in with extra moss until the orchid seems pretty well anchored in the pot. Use enough moss that the plant is clearly secured in the pot but do not pile the moss higher than where the foliage and/or pseudobulbs begin to push out root tissue. Once you have properly repotted your orchid you should actually be able to slowly pick up the plant and have the pot come up with it. If you pull on the orchid and it comes right out then you need to secure it better in the terra cotta pot.

Step four: Situating your newly planted orchid. Take your gravel or pebbles and place a layer of them in your slightly oversized saucer. What this does is create a buffer zone between the bottom of the saucer and the pot where the plant’s roots are. With this buffer, the extra water that seeps through when you water your orchids collects in the saucer. The excess water is not in direct contact with the roots, so you do not run the risk of rotting your roots, yet the water in the saucer slowly evaporates and provide much needed extra humidity to your orchid. Especially now while our apartments and homes are still closed up because it’s not warm enough outside, it is crucial to do all you can to provide your orchids with some level of humidity. Lastly, place your orchid in a location where it is going to get ample sunlight for that particular species, decent air circulation, and again, as much humidity as possible. If you place your orchids in a bathroom with enough light remember that even though the humidity will be great, you may also have to figure out creating additional air flow and circulation if there is no window or fan to have on or open.

From here, water and fertilize lightly and regularly, occasionally mist your plants if the species can handle it, and enjoy.

Monday, March 26, 2007

Canadian thistle in Pennsylvania

I have a patch of Canadian Thistle (Cirsium arvense) that I want to eradicate. I was told that changing the soil pH might help. Is that true? What is my best option to control this weed?

Canadian thistle (Cirsium arvense) is a cold-hardy perennial weed with a range that covers the entire northern US. It spreads by seed as well as aggressive underground rhizomes that can spread outward at least 15 to 20 feet. One reference even stated that thistle has allelopathic chemicals in its root tissue that helps to fend off other vegetation from establishing in its place. From book and internet descriptions Canadian thistle is tolerant of a wider range of soil types so I do not see how changing soil pH would be a strong enough deterrent to prevent the weed from continuing to spread. Not to mention if you make the soil too acidic (below 5.5) or too alkaline (above 7) then you run the risk of reducing all nutrient availability in the soil to the point where nothing will grow except the most noxious and determined of weeds.

For best control of Canadian thistle a combination of mechanical and chemical controls is the best option. Horticulturists and agriculturists alike are looking into natural biological controls that go after Canadian thistle, but most studies still appear to be in trial stages. Mechanically what you want to try and achieve is destruction of the carbohydrate storage tissue in the plants. Again, this type of thistle is most aggressive because of its long, carbohydrate-storing rhizomes. If the thistle is in an area that can be mowed, mow every three weeks to repeatedly cut back and weaken the plant’s tissues. Farmers usually keep livestock grazing in fields of thistle to achieve the same outcome. Canadian thistle typically flowers from late June through August, so do your best to prevent it from flowering and setting seed. Carbohydrate stores in the plant are at their lowest as the plant begins to flower, so June is a good time to enforce strong mechanical control. Even though not my favorite suggestion by any means, chemicals can be used in addition to mechanical control to really combat the aggressive nature of this plant. Foliar herbicides can be applied during the spring or fall, but most suggest that fall application works better. A systemic herbicide works to kill both the photosynthetic parts of the plant, leaves and stems, as well as the tough rhizome tissue underground. Slowly weakening the production of spreading rhizomes as well as deterring the plant from spreading seed, I believe you can begin to combat the thistles aggressive nature and hopefully get it under control after a few years.

Thursday, March 22, 2007

Gardening help in Buffalo, New York

I live in Buffalo, New York, and would I like to plant some shrubs, bushes, etc. in front of my house. I have nothing at this point. Could you recommend some books, info, that might help me in this particular area of the country regarding planting in cold weather zones.

First, you should make yourself familiar with your hardiness zone. Hardiness zones are determined by the average annual minimum temperature in a given region. In other words, this tells you the amount of cold that a plant can tolerate and still live in a given area. Buffalo to the best of my knowledge is Zone 5. Depending on your proximity to the water and if you get strong, freezing winds off the lakes then perhaps your area is colder, which would be a Zone 4. If your house is well sheltered then perhaps it is slightly warmer, Zone 6. The USDA hardiness zones do not take into account possible microclimates. Therefore, when shopping for trees or shrubs at your local nursery make sure that the plants you are buying are hardy to Zone 5. With this information, you can enjoy looking through reference books and seeing what you like, as long as it’s hardy to Zone 5.

Katherine Powis, the librarian here at HSNY, was able to find for you these titles that are sure to give you lots of great ideas. Cold Climate Gardening (a Taylor Weekend Gardening Guide) by Rebecca Atwater Briccetti. Tough Plants for Nothern Gardens by Felder Rushing. Northeast (SmartGarden Regional Guides) by DK Publishing. DK Publishing has a number of publications by the American Horticultural Society and they are all fabulous books.

Also, do not hesitate to contact your local cooperative extension to find out more site specific gardening information. Cornell cooperative extensions across the state are great places to turn to for city- or county-specific gardening tips and help. Go to and once on the website, click on the tab labeled “In Your Community”.

Tuesday, March 20, 2007

Where to buy Venus Fly Traps?

I live in Corona, NY. Where can I buy Venus fly traps?

The botanical name for Venus flytraps is Dionaea muscipula. They are a carnivorous plant native to the coastline of the Carolinas, and they reproduce and spread by rhizome, or underground stem.

I am not familiar with garden centers near Corona, NY, but I have seen the plants for sale at the garden shop at the Brooklyn Botanical Garden in Park Slope, Brooklyn, as well as the Shop in the Garden up at the New York Botanical Garden in the Bronx. Also, if you purchase from the internet, there is a great website called and they sell a number of native carnivorous plants. You might find that it also helps to do internet searches for other retailers if you search under the botanical name, Dionaea muscipula.

Jade Plant on Long Island, NY


I’m thrilled though to have learned that you will answer queries on plants as I have been trying to discern the state of my jade plant. It is of uncertain age, but I can tell you it was in an 8” pot and perhaps 8” high and not quite as round when I received it about 5 years ago. It had a quiet life in a city apartment then. In my sunny winter windows on the north shore of Long Island, it has been transplanted a number of times. It is currently in a pot measuring 12” high by 16” wide and the plant is about 18” high and almost 36” in diameter now!

I’ve attached a photo for reference.

It’s gotten too heavy to move outside in summer as of this year and was most recently repotted in the summer/fall of 2005. My question is do I need to repot it again? The soil is very hard, so I am tempted to water more, but I refrain. I get a small number of shriveled yellow leaves thru the winter but nothing alarming. I know that jades don’t want a lot of fertilizer, water or anything except sun, but I am suddenly in the care of a giant! I want to feed eat properly!

How long do they live? I’ve been taking a few cuttings but should I be cutting this plant back or thinning it? It has a wonderful symmetrical roundness now.

Also, I’ve seen the jades in the Camellia house at Planting Fields Arboretum flower in winter. Mine never has, and theirs appear ancient, not as full as mine, but almost 5 feet tall…what makes them flower?


And what a magnificent plant it is – I loved the picture! That is a certainly a beautiful specimen. To answer your first question, the plant will eventually need to be repotted, but I don’t think that is something that you are going to have to worry about for a few years, especially if you did it in 2005. It’s roots will continue to grow outward and downward, but at a slower rate. I do not see any need to prune it at all – it does have a fabulous shape. I have certainly seen plenty of jades perfectly content in almost pot-bound conditions, and continue to do fine for years. Otherwise you are certainly taking proper care of the plant. Never happy to be completely soaked, you can water a little more freely during the active growing season, (the summer months), but as you know already little to no water through winter.

As for how long they can live? They can go for a very, very long time. Growing up (I grew up out on the south fork of the island) I had a neighbor who had the largest, most unbelievable jade plants you can imagine. Honestly, she had four or five plants and they took up her entire sun room. Mrs. Fantini said that the plants were as old as she was, so that made them at least 90 years old! Granted as they get older they will not grow so aggressively, but you should expect to enjoy it for many more years.

Regarding getting them to flower, that is a question that I must admit I don’t have such a quick response to. The ones that I have seen flower have only been at aged conservatories where they have been settled and properly taken care of for years. I was recently up at the New York Botanical Garden and theirs was just beginning to bloom. There are ways of tricking various succulents into blooming, such as shocking them by putting them in total darkness, or dropping and raising the temperature of where they are growing, but I am very skeptical to suggest any of those for fear that the plant might get too shocked and go into decline. And it is certainly too amazing a plant, and too old a plant, to get experimental at this stage – at least that’s my opinion. I suppose regarding the flowers, all we can do is hope that as it gets more comfortable in its new home and pot it will eventually flower on it’s own.

Tomato issues in northern Dutchess County, NY

I have a home with a raised bed in which I grow a few vegetables. I go every year to the local nursery and buy a few different breeds and plant them. They do well the first few weeks, then they begin to look sick. They get these small, round, pale dots on the lower leaves. Sometimes with a black spot in the middle. The leaves turn brown and wither. Eventually the whole plant turns brown and dies. I do get a few tomatoes, but I've been used to robust plants that I used to grow in Brooklyn with a tremendous yield. On the internet I found a resource that said this was a mold or bacteria or something and the answer was to keep the lower leaves dry and not wet them when watering. This I did with no good results. They get plenty of sun and water. Not too much water. What do you think? Should I get those VGP disease resistant plants? How can I grow robust plants in northern Dutchess county?

Your situation certainly sounds to me like a fungal disease and not a bacteria or virus. Viral infections show a completely different set of symptoms, typically bizarre mosaic patterns on the foliage and stems, and it does not sound like that is the case at all. The black spots developing on the lower foliage and slowly moving up to take over the entire plant definitely sounds like a the spreading of fungal spores. If I had to narrow it down I would go ahead and guess one called Verticillium Wilt, which is known to be worst here in the northeast. The other close relative is Fusarium Wilt, but that fungus growers typically find further south.

To answer your question, yes, you should consider buying cultivars of tomatoes that are known to be more disease resistant. Since new cultivars seem to come out every year I cannot give specific names, but if the plant label has a capital “V” after the cultivar name then you can be sure that it is has been bred for better disease resistance. Otherwise, there is the homemade recipe for a foliar spray for fungal diseases and I am not sure if you are familiar with that. Using 1 gallon of water, mix in 2 tablespoons of baking soda and a drop of dish soap (to add a little viscosity), and once mixed use it as a foliar spray to cover as much of your crop as possible. Like with your watering, this should be done early in the day so that it cleans the leaves and evaporates before the scorching midday sun or the wet and cool evenings. Most people use this mix to combat powdery mildew and other issues, but I know plenty of people that use it on their veggie crops as well.

To cover all the bases, I’m also curious to know more about the raised beds you are using at your new home. Since you have experience growing successful tomatoes and other vegetables at your previous home in Brooklyn, I can’t help but wonder if the raised beds have adequate drainage. What do you think? Have all of the other vegetables you have grown in those same beds done well? I may very well be barking up the wrong tree, but perhaps the beds need to be double-dug to properly aerate and loosen the soil. If the soil in the raised beds is nice and loose but the soil from the ground level down has never been tilled then you could easily have a “perched water table”, and that water not being able to adequately drain all the way will only help further fungal issues.

Lastly, a couple tomato books that I have read here at our library suggest rotating your crops and growing your tomatoes in a different spot each year. I wonder if that would make a difference.

Plum tree fruit in East Haddam, CT

Here's one I have been asking for 3 years without an answer: My green/yellow plum tree in East Haddam, CT. gets fruit every year but the plums fall off, every one, by the time the fruit is the size of a large olive. The dark red plums do very well.

Have you ever seen any insect damage in the fallen, premature fruit?
There is a little beetle called a Plum curculio (Conotrachelus nenuphar). In spring, the adult females lay their eggs in the developing fruit, creating distinctive crescent-shaped slits. The hatched grubs eat the fruit tissue and eventually they fall to the ground. The grubs then leave the fruit, burrow in the soil, and pupate into adults. The damage seems visible enough though that you would have noticed it over the last few years.

Another question, and more difficult to answer. Do you know the species of the tree?
The genus is Prunus, that we know. The reason I ask is because so many fungal diseases and pests are very host specific, and knowing the exact genus and species of the tree might help narrow down the list down some. Again, I apologize, not the easiest question to answer.

Otherwise I am sure you are familiar with the general needs of the tree. Plums require full sun, well drained soil, soil pH between 5.5 and 7, and a regular watering schedule. If the tree consistently drops premature fruit I also wonder if supplemental watering might help the plant hold on to its fruit through maturity. However, if you have another tree in a similar location that is doing fine, again, I am stumped.

Training a Jade Plant

I have an indoor Jade Plant with three branches - each about 12 - 18 inches long. I middle branch is growing straight up but the 2 on either side are growing in an inverted U. Is there a way to get them to grow straight up?

To be perfectly honest, that sounds like a very comical looking plant. I personally have grown a few jades and the shapes that they take over time can be pretty unique. As far as how to train the two bent branches, my first thought is bonsai supports. Bonsai growers use a number of different metal structures and wire (from the most basic to the most complex) to carefully train their plants into the desired shape. Of the ones I have seen, you drive the base into the edges of the container or brace it to the bottom of the jade plant, and use the supports and wires to tie the plant stems in the desired direction. The one catch is that these structures, even though they help you train the plant the way you want it, they can be big and perhaps not what you want aesthetically. Now, if these two branches in question are very thick and mature, you might not be able to bend or train them very well at this point, but you could certainly try with new growth that emerges. Off the top of my head I am not familiar with bonsai stores or websites, but I am sure there are more than enough out there.

Evergreen issues in San Francisco, California

I have a garden with a large american elm, which faces two different evergreens, one a spruce and one a fir. On the branches that face the elm I have experienced lots of dropped needles. is there something about the roots or other element of the tree, like pheromones or some sense of closeness to other trees, which may be playing a role? this has been happening gradually over the last few years, and the evergreens in question are about 25 years old, with the very nearby elm pre-existent by at least as many years. but the pattern is striking, and would
suggest that to me. any advice would be appreciated.


Well, sure enough, a picture is worth a 1000 words, but I hope my advice doesn't go on quite that long! First, I want to clarify the two evergreens. The tall, more cylindrical tree (images 2385 and 2387) is neither a spruce nor a fir. It clearly is a scale-leaf evergreen which means it is most likely an Arbovitae or possibly a kind of Chamaecyparis. Arbovitae are a popular screening tree for that kind of narrow location where everyone is trying to achieve more privacy and screening. The catch is that Arbovitae need full sun to be their happiest. Therefore the holes/patches of defoliated branches are clearly signs to me of too much shade. The other tree (2386 and 2392) you are right, is either a kind of spruce (Picea) or fir(Abies). Here is a quick way of figuring out which one it is. Grab a piece of branch that has both needles and bare stem, meaning a piece closer to the center of the tree. Next, pull off a few needles one at a time. Spruce, when you pull a needle, leaves a little bump, or "peg" where the needle emerged. Hence the catchy phrase, "Picea have pegs". If you pull the needles and they take a tiny piece of the bark with them, leaving a clearly "circular leaf scar" where the needle emerged, then that is a fir tree. Generally people say that spruces are more hard and prickly and firs are softer and more fragrant, but typically that is not enough for a concrete plant ID. However, either way, both spruces and firs, yup, like sun also. Sounds to me, Aaron, like it's not an issue of a disease at all. And yes the space is limited, and for the roots as well, but honestly I think the problem is much simpler. The elm is slowly shading out the other two trees. It grows as fast as the other two, especially if the other two don't get enough sun, its canopy casts more shade, and it makes sense that you have been watching this gradually happen over the last five years. The Arbovitae is going to continue to lose needles on the side facing the elm because that's the shadiest. The fir/spruce/? will also continue to drop needles from the base upwards. You have new growth on the tips of both evergreens so they are still alive, but just getting out competed for the necessary sunlight. At a cost arborists may be able to come in and thin out the canopy of the elm to allow a little more light through, but it might be worth thinking about what you want to do in the long run. Certainly you can cut the dead branches off the evergreens because they will not leaf out again from those spots.

Night Blooming jasmine in Bronx, NY


I received a rather tatered looking night blooming jasmine as a gift from a freind who is leaving the coutry. His advice was to water frequently. My questions are how frequently is "frequently" and how do I keep the palnt alive in a bronx apartment? It seems to have what looks like white dust--mold? -- on some of the leaves.


To start, let me give you a little general information about night blooming jasmine. Even though the plant looks and blooms like a jasmine, the funny thing is that it is actually not a jasmine. The proper botanical name is Cestrum nocturnum. I usually find that if you are doing searches on the internet, either to find care information or to find images to confirm that the plant is what we think it is, it helps to search by the formal botanical name to find more credible sources and help forums.

Ok, so, on to your plant. As I mentioned, jasmines and night-blooming jasmines are different plants, but their wants and behaviors are quite similar. And your friends watering suggestions are mostly correct, but I should clarify. Your plant does like frequent watering, but only during it’s active growing season, which is typically summertime. That means that during the winter months when there is less sunlight throughout the day, the plant slows down and its “metabolism”, for lack of a better word, is not nearly as active as during the summer months. For this reason, in winter you want to water your night-blooming jasmine much less often. If the plant is getting a lot of water and unable to take it into it's roots as quickly as in summer, then that water sits in the soil and begins to cause disease issues. The main issue, as it sounds like you have already discovered, that can result from this is an unsightly fungus called powdery mildew. It is not going to kill the plant necessarily, but it is ugly and the plant will be happier without it around.

Moving forward, keep the plant watered, but don’t be afraid to let the soil dry between waterings during the winter and early spring. What I mean by that is water maybe a little bit twice a week. You don’t want the plant to completely dry out and die, but you also don’t want it to be soaked. Right now it needs enough water to stay alive, but not much more than that. It likes sun so close to a window with bright light or some direct sun should be fine. If you have a heater nearby, take that into account as it may be making the plant dry out faster than usual. As the weather gets nicer and the days get longer, feel free to gradually give it more water. You should see that it will be growing more and putting out new leaves and stems and by the summer you can be giving it a couple of glasses of water a week. As for the powdery mildew, you can take a wet paper towel with a little bit of soapy water and clean the white film off the leaves. As soon as it’s nice enough to open the window and get some fresh air in, that is going to be a major help too. Most plants really don’t like to be stuck in these closed up apartments all winter so I think you will find that fresh air will also help the plant out a lot.

Well, now that I have loaded you up with information, I hope that helps. Keep it in a sunny spot and if fresh air is an option, go for it. Water less for now and as the spring rolls into summer, water it more frequently. Lastly, let me know if you have any further questions and I’ll be happy to answer them.

New Guinea impatiens in south Florida


I live in South Florida and have planted New Guinea Impatiens near some hedges and around a tree. I fed them with osmocote and have been watering them every other day. I water them fairly early in the morning, before the sun comes up. Lately, I have noticed that some of the leaves are bleaching, i.e., there are some white spots developing. I should add, that I was watering them every day, but I stopped about a week ago. Do you think that there is anything I can do?


You situation sounds to me like a case of powdery mildew. If the plants are below hedges and under trees I might worry that they are not getting quite enough air flow. If you are watering so often and that water is not getting the chance to completely evaporate during the day then the foliage of your plants can develop the unsightly white fungus. It is not going to kill the plants necessarily, but it certainly does nothing for the aesthetics of your garden. There are recipes for a homemade concoction of water and baking soda (2 tbsp. baking soda per gal. of water), and a drop of dish soap for viscosity, and applying this as a foliar spray. That usually does the trick, even if you have to do a few applications over a couple weeks time. You may choose to do this in addition to lightening up on your watering schedule.

You are already watering your plants at the right time of day. Typically early watering allows for proper evaporation during the day, but again, it might be more an issue of restricted air flow. You mentioned at the end that you were going to water less. Did that help? From my experience, granted a couple hundred miles away, I have found that impatiens can tolerate a fairly dry setting and still perform well. Perhaps you do not need to be watering them every other day.