The Bay Gardener by Dr. Frank Gouin

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Keeping Plants Happy Indoors

Learn to balance food, light and water

Daylight hours are getting short, days are becoming cooler and the intensity of light in the home will be considerably less than the plants were experiencing outdoors. When you combine all of these important growth factors with moving plants indoors, you’ll need to modify feeding practices. Unless you are placing your plants under artificial indoor lighting to extend the day length, most houseplants almost stop growing after being brought indoors. Thus it is important that you stop feeding for at least one month. But don’t neglect their irrigation needs.

There is a tendency to overwater houseplants when they are initially brought indoors. To know when to water, press your finger firmly into the potting medium. If the medium feels cool and moist, don’t water. If the medium feels warm and dry, add sufficient water so that an excess can be seen draining through the bottom of the pot. 

If the leaves on your plant begin to turn yellow, this is a clear indication that there is insufficient light to satisfy their needs. Houseplants that are grown outdoors tend to have thicker leaves than plants grown indoors. Thinner leaves tend to burn when plants are moved outdoors in the spring and summer months.

There is nothing that can be done to prevent yellowing and loss of leaves other than providing additional lighting. Growlux lights are ideal for growing plants, but they must be placed within inches of the foliage to provide maximum intensity. Supplementing Growlux lights with two or more 40- to 60-watt incandescent bulbs will help considerably, allowing more space between the light source and the plant. Light the plant for at least 10 hours for the first two to three weeks.

In Florida and California, foliage plants are grown outdoors because they reach marketable size more rapidly. This practice is used by the commercial growers prior to shipping their plants north so that their foliage will not turn yellow and drop after they arrive at their destination.

Diagnosing Cherry Laurel Trouble

Q Your column in Bay Weekly is a great source of information on local gardening, and it’s one of my must-reads each week.

Could you please give me some guidance on how to treat a rampant case of fungus that has overtaken my beautiful Otto Lukens cherry laurel shrub? It is one of my foundation plantings, and I’m concerned that the disease will spread. Most branches of the laurel are covered with a white powdery substance, many leaves have turned brown and some branches have withered. I have sprayed the shrub with the fungicide Serenade, but it doesn’t seem to be working. Is there anything else I can do to save this shrub? Or is it a goner and should it be removed before it infects other plantings?

Many thanks for your expert advice!

–Marie Loucks, via email

A I do not know of a white fungus that attacks cherry laurel. It sounds to me that you have a very bad infestation of oyster shell scale. Examine the branches and stems for any white crusty areas. If you look closely with a hand lens, you might notice that they look something like miniature oysters.

Spray the plants thoroughly with a four-percent solution of horticultural oil, summer oil or volch oil. They are all the same. The oil will suffocate the scale.