|Succulent Plant Site | Asclepiads | Cultivation
Cultivation of Asclepiadaceae
The successful cultivation of these variable genus' depend on numerous factors. The following is a guideline to the cultivation of plants in the Asclepiadaceae, the best teacher though, is experience.
Soil, Pots and Potting
Soil, with root mealybug is probably the most discussed topic amongst growers of Asclepiads. These plants require a well drained soil that dries out quickly enough to prevent rot. Peat based potting soils tend to attract root mealybug and it in its self is a big enough problem as it is therefore I do not use peat-based mediums with my Asclepiads. Below is my general mix for my plants.
8 parts grit, 2-3mm
4 parts soil
4 parts washed riversand
2 parts well sieved compost
Check this page out, it's a list of medium components and what their purpose is in growth mediums. What peat is etc.
Your soil mix, whatever it may be, should be sterilized before use. An effective and safe method of sterilizing your soil is to "bake" it in an oven at 120C for an hour or two. A friend of mine sterilizes his soil using a microwave oven, full power for 20 minutes. The purpose of sterilizing your potting medium is to kill off pests and diseases, e.g. fungal spores, weed seeds, pests and their eggs.
Round, square, plastic and clay pots, they all have their advantages and disadvantages. The ideal pot would be a square unglazed clay pot, square to save space when packing and clay to allow your medium to dry out quicker. Clay pots should be unglazed, glazed pots retain moisture for a longer period of time than unglazed clay pots. The advantage of clay pots is that it allows your medium to dry out quickly but a disadvantage could be the price and their tendency to break when dropped. Plastic pots are a lot cheaper but they retain moisture for a longer period of time, not ideal for plants that are prone to rot. Circular shaped pots are aesthetically pleasing to the eye but they use up a lot of space.
Size matters, as well as depth. Plants grown in 15cm to 17cm pots do well but the deeper the pot the better. My choice of pot is a square 15-17cm plastic pot, cost effective and a great space saver. I also live in a dry climate so I don't have to worry too much about the plastic pots retaining moisture. People living in cold, wet or humid climates will find that clay pots will suit their growing conditions.
If you re-use your pots it is a good idea to sterilize them between uses. Plastic pots can be sterilized using Jayes fluid (carbolic acid), follow the dilution instructions, wash the pots thoroughly and rinse them well. Traces of carbolic acid will kill your plants. Clay pots are a little more difficult to clean, I use standard dish washing liquid and give them a good scrub. After scrubbing them I soak them in hot water (be careful not to crack your pots).
The potting of Asclepiads is not really a difficult task, some of the more difficult ones to grow require a different potting method. You can always tell which are the difficult ones, their price tag usually gives them away. My standard potting method is as follows:
Make sure you use clean pots, if they are not clean sterilize them. Root mealybug is a prolific pest.
Put a 1cm-1.5cm layer of clean gravel at the bottom of the pots. This facilitates drainage and prevents a salt buildup that could eventually turn toxic to the plant.
Fill the pot with your medium up to 2-3cm to the top (the ridge on the inside of plastic pots), use your own judgement if you need more or less space for roots, size of plant.
Pat the soil down, to get rid of air pockets.
Put your plant in and fill up to the ridge, patting soil down gently to get rid of air pockets.
A top covering can be used to make the plant look nice in the pot but this top layer retains moisture. I usually just put a 0.5cm layer of coarse grit on the top.
For difficult to grow plants follow the above method but put the stem in a layer of coarse grit above the growth medium. The layer of coarse grit dries out fairly quickly which keeps the stem dry (many Asclepiads dislike being wet or too damp for long periods of time) and helps prevent rot.
Stagnant air caused by poor ventilation can cause numerous problems. Poor ventilation makes your plants more susceptible to fungal diseases and pests. Plants will flower less as well.
The solution to ventilation problems are simple. Install an extractor fan or use a normal fan to circulate the air, don't let the fan blow directly onto your plants.
A difficult aspect to give advice on, the best advice is your own experience. Allow the medium to dry out before watering again, don't keep the plants dry for too long. Water early in the morning on sunny days, this will help dry the top of the medium out (all in aid of preventing rot). Watering can be done from above or below, no damage should come to your plants.
I've rigged my greenhouse out with overhead atomizers which emits a fine spray over the plants. The watering system is connected to a tank, via a pump, that is filled with fresh water from the Orange River (forms part of the border between South Africa and Namibia).
Use a well balanced inorganic fertilizer. Foliar feeding is the easiest but if you are lucky enough to have an overhead watering system you can add fertilizer to the water and feed at every watering. A quarter of the recommended amount can be added to your water, this is the amount that I have tried with quite a bit of success.
You must water your plants with clean fresh water every now and then. The purpose of this is to prevent a salt build-up, either from fertilizers or poor mediums, which can become toxic to your plants.
Light effects the growth of your plants in many significant ways. Direct sunlight may burn or stunt your plants preventing flowering and growth. Too much shade makes your plants susceptible to disease like rot and mealybug, they are also more easily damaged.
The intensity of light the plant receives should be taken into consideration when looking for a place to grow. Growers in the UK can give their plants more light while growers in the southern parts of the US need to give them more shade.
Hoodia, Larryleachia, for instance, can be grown in full sun, this doesn't mean you can move plants from a greenhouse environment to direct sun. They would have to be hardened up first, this is accomplished by gradually exposing the plant to more intense light before placing it in full sun.
Most asclepiads need temperatures of +15C to grow well in.
The Stapeliads are extremely susceptible to root mealybug and rot. Root mealybugs are small soft bodied insects covered in a wooly substance. They attack the plants roots and underground stems. These pests are usually detected when the plant collapses from a secondary disease, rot, caused from the pests biting into the roots. If your plant starts to go yellow or discolored then this is the first thing to look for. Gently move the soil away from the base of the plant to expose the roots to see if there is any root mealybug.
Treatment for root mealybug requires a pesticide. Soak the pot in a solution of pesticide for a few minutes then remove. To help prevent root mealybug infestation plants should be dipped in a pesticide solution at the beginning and end of every active growth season. Mothballs are reputed to keep these pests away, put a couple of mothballs on top of the soil.
If the infestation has caused rot you will have to cut away the affected areas, treat the plant with a fungicide and root. (See Propagation)
Excessive watering, poor drainage and poor ventilation can also cause rot. See previous paragraphs to help with these problems.
Red Spider Mites like to infest leafy Ascleps like Brachystelma especially the species that have fine hairs on their leaves. Red Spider Mite is relatively easy to treat. A poison like Amitraz will get rid of them or an environmentally friendly treatment, which follows, should help.
Soak twenty cigarette stubs in one litre of water for a week. Add 2.5ml liquid soap, which acts as a spreader/sticker/suffocator to the cigarette water. This should also work for mealybug. The soap suffocates the pests and the tobacco chases them away. Simply spray it onto infected plants.
A piece of rotten Tromotriche revoluta. The rot was caused by root mealybug.
mb causes rot
red spider mite - plants with pubescent leaves