Factors to Consider When Using Worm Castings
Though they may not provide a complete fertilizer for all plants, worm castings are powerfully rich in nutrients. A home worm composting bin will produce a small quantity of castings at a time. Choose where you will use them so that they do the most good, and use them sparingly.
Do not plant in pure castings alone. Mix with other materials such as soil, peat, sand or leaf mold. Castings contain many elements including nitrogen, phosphorus, potassium, and calcium so that they form salts if used in too high a concentration. The potential for salt formation is diluted by mixing castings with other soils, leaf mold, peat, or planting materials.
Be aware that castings are alkaline, so they may not be appropriate for all acid-loving plants.
Mix ¼ castings with Perlite, peat moss, sand, and/or soil for potting plants. For plants already potted, sprinkle about ¼” castings on top of the soil around, but not touching, the plant’s base. Make sure excess water is allowed to drain from the pot when it is watered.
New Seeds and Transplants
Castings may be used similar to blood meal when planting seeds and transplants. For seeds, make a row for planting, sprinkle castings along the prepared soil, and plant.
Before setting transplants in the garden, throw a handful of castings in the hole. The surrounding soil will dilute any excessive salt concentrations in the castings.
Sprinkle ¼” of castings on the soil around the base of the plant, but not touching the plant. This is referred to as “topdressing.” Water in. Repeat every 45 to 60 days if you can get that much yield from your worm bin.
Mary Tynes, Master Composter, www.mastercomposter.com
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