Gardening : What Is Preferred Time of Day to Water Plants?


QUESTION: I’ve always heard that watering camellias and other large-leaf plants during the heat of the day will burn the foliage. Is this really true? Is there a preferred time of day for watering the plants in my yard?

ANSWER: According to George Pinyuh, a Washington State University Extension agent, research counters this time-honored but misinformed notion. In fact, he points out, the water would have to be about six inches deep on a leaf to burn the foliage. Even so, remember that watering during the heat of the day wastes water, since much of it turns to vapor and escapes into the air.

With regard to timing, generally plants should be watered early in the morning, for two main reasons: to save water and to help control plant diseases.

If you have an automatic watering system, it is ideal to set the clock so all stations operate between 2 a.m. and 7 a.m. Even rose foliage sprinkled at this time of day will usually have much less trouble with powdery mildew, if the plants are situated in a well-ventilated area in full sunlight. That’s because this early watering encourages the fungus spores to germinate, and daytime conditions destroy them. Evening watering, on the other hand, gives disease organisms time to develop protection against the light and dryness of the day and actually promotes their growth.


Wind and evaporation waste a surprising amount of water that runs through sprinklers on hot or breezy days. But in the normal calm and cool of early morning, most of the water soaks into the soil.

This having been said, bear in mind that new lawns and other new plantings require extra attention to watering for a while, especially on hot or windy days. But for established plantings, morning watering is definitely preferred.

Benefits of Using Mulch in Gardens

Q: I’ve been told that it is good to put one inch of mulch around plants in my garden. Does mulching really help? If so, what kind should I use?


A: Mulching really does help. It conserves moisture, retards weeds and promotes plant growth.

Ten or 15 years ago a major university studied the effects of mulches on permanent plantings. They reported that a 3- to 4-inch depth of any organic matter around plants would significantly increase their growth and flowering while reducing the amount of watering needed. Interestingly enough, they concluded that gardeners should use whatever organic mulch is readily available to them at the lowest cost, and it works.

For instance, the large public rose garden in Hershey, Pa., is heavily mulched with (what else?) cocoa hulls, which are plentiful there and which fill the air with a wonderful rich chocolate aroma. In a Seattle public garden the workers mulch with an ever-ready supply of elephant manure from the neighboring zoo; they call it “zoo-doo,” and surprisingly (fortunately) it has no noticeable aroma.

Around here I have seen successful mulches of wood shavings, aged steer manure (but this smells for a while), rice hulls and even almond hulls, when they can be found. Be aware that you will also need to feed your plants regularly when you mulch them; and then stand back and enjoy their growth.


Getting Fruit Trees to Bear Annually

Q: We have a plum tree that fruited well for the first time this year. What can we do to ensure a good annual crop?

A: Many fruit trees tend to bear heavily, then lightly, in alternate years. This tendency can be controlled somewhat by (1) proper winter pruning, (2) feeding just before flowers appear in spring and (3) thinning the fruit when it’s about half-an-inch long. Weather factors during the winter and at blossom time also affect fruiting, but these we cannot control. So we do what we can, and then let nature take her course. Good Luck.

Treating Chlorosis in Geraldton Waxflowers


Q: I have two large Geraldton Waxflower plants (Chamelaucium uncinatum) about 3 years old. These have grown very well and bloom profusely, but there is a problem. Much of the foliage is yellow, which I assume is chlorosis, but it does not respond to treatment with iron chelate or other things I’ve tried. What do you suggest?

A: Geraldton Waxflowers--which have needle-like leaves and produce long-lasting, wax-like pinkish flowers in winter--are native to parts of Australia with dry, quick-draining, rather alkaline soils and bright sunlight. They will not tolerate any acidity around their roots, and they will sulk and decline if they receive more water than they “want.”

Chlorosis is the unhealthy yellowing of newer leaves, usually with darker green veins showing. Although the chlorosis you describe may be related to a slightly acid soil condition, it is more likely, since your plants are still alive and growing, that the plants simply get more water than they can tolerate. Geraldton Waxflowers thrive on neglect when planted in rapid-draining soil and watered deeply but infrequently.

Brown Flecks on Fruit Is Sign of Sweetness


Q: Some of the fruits on my apple and nectarine trees have brownish flecks or streaks on the skin, while others are pretty and uniformly colored. What causes this, and what can I do to get rid of it?

A: What you describe sounds to me like “russetting,” which is a thin, sort-of-corky layer of cells on the skin of certain fruits, usually more pronounced on the “shoulders” or near the stem-end of the fruit. Pippin apples are famous for their heavy russetting.

This kind of russetting usually forms on susceptible fruits developing in direct sunlight. Thus, these fruits tend to be sweeter than the prettier, more uniformly colored ones. There is really nothing you can do to eliminate the russetting; but you might take note that these “ugly ducklings” are usually the sweetest fruits on your trees.