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SO Gardening May 31

Sunday, May 31, 2020

Dear Orchid Doc:

Do orchids need to be fertilised while they are in flower? If yes, what fertiliser should I use?


Concerned Reader


Dear Concerned Reader:

Yes, if anything, flowering plants need extra fertiliser. Your plants will need to be fertilised with a product appropriate to the medium in which they are grown. In general, plants in a bark-based mix will need a fertiliser high in nitrogen (usually in a 3-1-1 ratio), while a balanced fertiliser will do for all others (usually a 1-1-1 ratio). If in doubt, fertilise with the same balanced fertiliser you use for your other container plants.

Orchids will do far better with too little fertiliser than with too much. The old adage, “feed weakly, weekly” is appropriate. Fertilise every week with a dilute solution.


Dear Orchid Doc:

What is the best orchid for growing in the home?


New Grower


Dear New Grower:

One of the most widely available orchids of the mass market types is also the best for the home — the Phalaenopsis or moth orchid. Many homes have insufficient light levels for the reflowering of most orchids. However, there are a few orchids that will grow in lower light and will reflower under home-light conditions. Home-light means light provided by a slightly shaded south window, or an east or west window. Phalaenopsis will grow easily under the same conditions enjoyed by African violets.

Another good choice, but usually only for those already initiated into orchid appreciation, is Paphiopedilum or the slipper orchid. These, like the Phalaenopsis, have relatively attractive foliage, and will reflower in home conditions giving weeks of floral display. Both need to be kept evenly moist. Do not allow to fully dry out, and fertilise regularly with a weak dilution of any available fertiliser.


Dear Orchid Doc:

My orchid's leaves are wrinkled and leathery. Why?




Dear Chantal:

Lack of water or dehydration. The next step is to determine why the plant is not getting sufficient water. First, look at the roots. If they appear a healthy white or green and are plump, and the medium is in good shape, suspect underwatering, especially if the roots are white and the pot is very light. If, on the other hand, the roots are in poor condition, suspect root loss. If the plant has no roots, it cannot take up any water, no matter how much you give it. In this case, the cause may be root loss owing to overwatering or medium deterioration, or a recently repotted and poorly established plant. The immediate solution is to raise humidity in the plants' vicinity to reduce stress on whatever roots there may be, and then deal with whether to repot or to simply wait until the plant establishes in the fresh medium.


Dear Orchid Doc:

Why are my buds turning yellow and falling off?




Dear Kelly:

This is referred to as bud blast, and can be caused by the following conditions:

The plant has been too dry between watering, causing it to withdraw moisture from the buds.

There may be some wide swings in temperature, where it may be too hot in direct sun, or the plant may be too close to an air-conditioning or heating vent.

There may be some fumes in the air caused by paint, natural gas leaks, or other chemicals. Flowers naturally create their own methane and collapse after pollination to save energy for seed production. Certain forms of methane or ethylene may trigger bud or flower collapse.

Cattleyas in particular are sensitive while in bud to overwatering, causing the buds to actually turn black in the sheath.

All plants need an adequate amount of light in order to flower correctly. Placing a plant in the centre of a room, on a coffee table for example, is fine for display during an evening of entertaining, but to maintain proper growth and flower development it is best to keep the plant in its growing area (near a window or under lights).


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