GROW POWDER

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Use up to 20 lb./100 sq. ft. Lasts up to 10 years. • Kelp meal and liquid seaweed (1% N, 0% P,1.2% K, plus up to 33% trace minerals). This ocean-based K source is rich in trace minerals and natural growth hormones. As the seas have become more polluted, though, some growers have expressed concern about using kelp for more than 1 or 2 years. Apply sparingly—no more than 1 lb./100 sq.ft. per year (dilute liquid seaweed to labeled specifications). Lasts 6-12 months. • Wood ashes in general (0% N, 0% P, 1-10% K, though amounts are highly variable). Wood ashes (hardwood are best) raise soil pH as well as adding potash. Protect winter ashes from rain leaching. Use up to 2 lb./100 sq. ft. Lasts 12 months and longer.

pH and More:•

Lime. Whenever I asked a question about lime (crushed limestone), the answer was sure to be much more than I bargained for. Conventional wisdom holds that lime is what you add when you need to raise pH—the measure of potential hydrogen ions that determines a soil's sweetness (alkalinity) or sourness (acidity). But it turns out there just isn't a simple, all-purpose pH-boosting lime. First, there's dolomitic lime (also called highmagnesium lime), which has about 20% magnesium and is used where the soil needs magnesium as well as calcium. Then there's hi-cal lime (also called calcitic lime or calcite), which has only about 5% magnesium and is recommended where there are already adequate or excessive magnesium levels.

(Oyster shell lime is a good substitute if hi-cal lime is not available.) What's all this stuff about magnesium and calcium got to do with pH? Well, the very simplified explanation seems to be that "good" pH is more than just a number on a litmus scale, but entails a proper balance of potassium, magnesium, calcium and sodium. Here again, a good soil test will help you properly address the situation.

• Gypsum, also called land plaster or calcium sulfate (23-57% calcium, 17.7% sulfur). This natural, mined source of calcium and sulfur is used where magnesium needs to be reduced and calcium added, but where pH levels are already adequate or even too high. Use only as indicated by a soil test, from 110 lb./100 sq. ft. Do not use dry wall as a source of gypsum. It contains other chemicals and contaminants.

• Clodbuster or Leonardite (approximately 15% humic materials, 15% humic acid). These crushed deposits of ancient plant and animal remains (from New Mexico) are a source of concentrated humates and humic acids that help make nutrients available to plants (compost also provides these goodies). Apply in the fall or at least a month before compost is added. Lasts 12 months.

• Fish emulsion (4% N, 4% P,1% K). Use this concentrated liquid fisheries waste product to give a nutrient boost to seedlings after their true leaves appear. It's also used as a foliar feed spray in the garden.

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