Fertilizers made from plants generally have low to moderate N-P-K values, (See: Nutrients Plants Need), but their nutrients quickly become available in the soil for your plants to use. Some of them provide an extra dose of trace minerals and micronutrients. If you don’t find plant-based fertilizers at the garden center, check out your local feed store. The most commonly available plant-based fertilizers include

• Alfalfa meal: Alfalfa meal is beneficial for adding nitrogen and potassium (about 2 percent each), as well as trace minerals and growth stimulants. Roses, in particular, seem to like this fertilizer and benefit from up to 5 cups of alfalfa meal per plant every ten weeks, worked into the soil. Add it to your compost pile to speed up the process.

• Compost: Compost is mostly beneficial for adding organic matter to the soil. It doesn’t add much in the way of fertilizer nutrients itself, but it does enhance and help make available any nutrients in the soil. (For more on compost, see the section “Composting: Turning Waste into Garden Gold,” earlier in this chapter.)

• Corn gluten meal: This powder contains 10 percent nitrogen fertilizer. Apply it only to actively growing plants because it inhibits seed germination. Use it on lawns in early spring to green up the grass and prevent annual weed seeds from sprouting.

• Cottonseed meal: This granular fertilizer is particularly good at supplying nitrogen (6 percent) and potassium (1.5 percent). Look for organic cottonseed meal because traditional cotton crops are heavily sprayed with pesticides, some of which can remain in the seed oils.

• Kelp/seaweed: You can find this product offered in liquid, powder, or pellet form. Although containing only small amounts of N-P-K fertilizer, kelp meal adds valuable micronutrients, growth hormones, and vitamins that can help increase yields, reduce the plant stress from drought, and increase frost tolerance. Apply it to the soil or as a foliar spray.

• Soybean meal: Used in pellet form, soybean meal is prized for its high nitrogen (7 percent) content and as a source of phosphorous (2 percent).

When looking at organic fertilizer products, you’ll invariably come across those containing humus, humic acid, or humates — organic compounds often found in compost. These products have no fertilizer value, but rather are used as stimulants to support soil microbial life that, in turn, supports the plants. Use them as supplements, not to replace proper soil building and nutrition.