Are you starving your garden? Compost is usually sufficient food for most plants, but occasionally some may need more. Whether you're growing flowers, foliage or vegetables, shrubs or trees, they'll tell you if they need food. Here's what to watch for:

NITROGEN DEFICIENCY: Leaves are small, shoots are short and small in diameter, plants generally lack vigor, and older leaves turn chlorotic (yellowish), while younger leaves (at the top of the plant) are still a normal green.

Other disorders may look like nitrogen deficiency: problems such as root constriction, root pruning, insect pests, poor drainage, soil compaction, and restricted aeration, for instance. If soil is sandy, nitrogen is easily leached out, so it may need replacement. Correct with blood meal, fish meal, fish emulsion, alfalfa meal or even coffee grounds.

PHOSPHORUS DEFICIENCY: Upper side of leaves may be dark green, but veins on underside of leaves purple. Leaves may be small and sparse, flowering less than to be expected (and reduced fruiting).

This deficiency is rather rare unless plant is growing on what's left after topsoil has been removed.

Some herbicides leave damage similar to phosphorus deficiency, including leaf distortion and reddish color to the leaves. In early spring, seedlings may show purple veins on under sides of leaves because of chilly nights, not phosphorus deficiency.

If deficiency is real, correct with bone meal or rock phosphate (the latter is not a quick fix). If you have pets with access to this area, bury bone and/or blood meal and bar pet access to these substances.

POTASSIUM DEFICIENCY: Older (lower) leaves may wilt or look scorched. Chlorosis of the lower leaves. This is not a common deficiency, but correct with greensand or wood ashes. Wood ashes will increase the alkalinity, so you may want to use greensand instead.

IRON DEFICIENCY: Chlorosis of the newer or upper leaves, veins green.

Iron deficiency may be tied to pH, or alkalinity of your soil. Our soil is naturally quite alkaline, and if you've put wood ashes or gypsum on it, it may raise the pH to a point where iron is not taken up by plants. Use chelated iron as a foliar treatment.

SULFUR DEFICIENCY: Younger (top) leaves turn yellow first, lower leaves also may turn yellow later. Sulfur lowers the pH (makes soil more acid).

Whenever you see unusual growth, failure to thrive, misshapen or undersized leaves, watch that plant and try to learn what's happening, so you can correct it. Some symptoms of nutrient deficiency are similar, so make sure your diagnosis is accurate before trying to correct the situation.

Cold, wet, poorly-drained soils will produce plants with many of these symptoms of deprivation, so don't leap to the conclusion that your plants are starving. Too much fertilizer attracts destructive insects.

A little remedial fertilizer such as fish emulsion often corrects a poorly performing plant. Remember, if a little is good, a lot is NOT better. An excess of some elements may block availability of other needed nutrients. Some people, for instance, try to use pieces of drywall in place of gypsum, and that produces an excess of calcium that can bar availability of other nutrients.

If your plants are not thriving, although not showing any signs of nutritional deficiency, try foliar feeding of fish emulsion fertilizer. It contains trace elements that plants need, and won't do any harm, if applied according to label directions.

Early morning, when it's still cool, is the ideal time to do any foliar feeding. When the day turns hot, the stomata, or pores of the plants, shut down for self-preservation. When temperatures are cool or moderate, they're open to foliar feeding. There are more stomata on the undersides of leaves than on the tops of leaves, but it's difficult to spray on the undersides of leaves, especially when the plant is small and low to the ground. Spray or sprinkle diluted fertilizer on the tops of leaves.

In Treasure Valley soils, we may have a deficit of magnesium, indicated by leaves lighter green than they should be, for instance. Dissolve one teaspoon of epsom salts (magnesium sulfate) in a pint of water, and spray on the foliage early in the morning. Leaves should darken to a normal green in a few days.

Further complicating self-diagnosis is the fact that some herbicides blown in or accidentally introduced may create symptoms mimicking nutrient disorders. When in doubt, take a small branch to the Extension office for diagnosis.

HERBICIDE CAN DISTORT VEGGIE SHAPE

Diseases can result in deformed plants and vegetables, and now there's a man-made herbicide that distorts the shapes of vegetables, even potatoes, on secondary exposure. It's a fairly new product from Dow AgroSciences, called aminopyralid. They are manufacturers of clopyralid and picloram, herbicides that are notoriously persistent through composting. Apparently aminopyralid is too.

I've not yet heard of problems with aminopyralid in the United States, but in England market gardeners and many allotment gardeners are furious that the year-old cow manure they bought carried this devastating herbicide. The cattle had grazed on a pasture sprayed with Forefront, active ingredient aminopyralid. It still was potently herbicidal after passing through grazing animals.

Milestone is the name of another product that has aminopyralid as an active ingredient that has been tested, at least, in Idaho, according to the University of California's Cooperative Extension newsletter. There may be more brand names, too, so always read labels before you buy a product and beware of buying manure or compost produced by animals that have lately grazed on sprayed areas.

Dow AgroSciences, in self-defense mode, is advising English gardeners whose crops have been damaged by their herbicide not to consume or sell the distorted produce. Nobody knows whether it's safe.

PLANNING A FALL VEGETABLE GARDEN?

If you're planning an autumn vegetable garden, start your seeds indoors soon. Most vegetables germinate best at 70 degrees or below. Broccoli, cabbage and other brassicas prefer 45 degrees, but that's very hard to achieve in this weather, even in air conditioned structures. Once germinated, seedlings can then be moved into hot temperatures.

The Ball Redbook for Greenhouse Growing reports seeds for petunias, geraniums, impatiens, begonias, salvias, lobelias, marigolds and vincas germinate best if the soil temperature is 75 degrees, so start them indoors, too. Watering with cold water quickly chills the potting soil temperature, so always use tepid water on seedlings.

Count back from Oct. 10, our average first killing frost, to determine when to plant for fall gardens. For instance, most cabbages take 60 days to harvest. You then should plant cabbage before Aug. 10 (give it a few days to germinate). Brassicas and other frost-tolerant crops give you some leeway in planting times, but a second crop of snap beans is not forgiving of frost.

REPLANT PARTS OF HARVESTED LEEKS

When you harvest mature regular leeks, cut off the bottom about an inch above the roots, and replant that. I'm told it will regrow. One expert told me she replants leeks like that three times before starting over. I've not enjoyed success with this replanting in my sole effort.

When last year's leeks bloom, feel around the roots for some flat bulb-like growths. They can be used to flavor foods or to replant, but I've not found they live beyond the parent leek much, if at all.

Margaret Lauterbach: melauter@earthlink.net or write to Gardening, The Idaho Statesman, P.O. Box 40, Boise, ID 83707