The Q&A Archives: Organic Fertilizer

Question: I'm growing herbs and vegetables from seed to be grown in containers (some indoors and some outdoors). I would like to use an organic fertilizer that is water soluble. The only kind I have found is a fish fertilizer (5-1-1). Should I use this on my seedlings and it seems as if it is high in nitrogen and less in the other two nutrients. There are plenty of dry organic fertilizers but I don't quite know how to keep mixing it into the soil of my container plants let alone into my seedling soil. Also, I don't know what percentage of nutrients to use. It seems as if there are few fertilizers with perfect 20-20-20 or 10-10-10. Do you know of a particular brand or where I might purchase a liquid organic fertilizer.

Answer: I congratulate you for wanting to grow organically! Adding compost is one of the very best things you can do to improve your soil. Compost improves soil structure, making it more workable, it improves drainage in clay soil, improves moisture retention in sandy soil and provides food for beneficial organisms, like earthworms. However, the nutrients (nitrogen, phosphorous, potassium--the NPK listed on fertilizer containers) in compost can vary considerably. So until you build up an extremely healthy soil, it would be a good idea to add some nutrients. Organic fertilizers also vary in their NPK ratios, so try to create a fairly balanced mix, such as 10-10-10. Some organic fertilizers follow:

Nitrogen: alfalfa meal, blood meal, coffee grounds, cottonseed meal, fish emulsion, seabird guano.
Phosphorous: bone meal, rock phosphate
Potassium: greensand, seaweed, kelp.

Mix your own with the above materials to make a custom blend specifically for what you're growing.

In general terms, nitrogen produces lush
green growth, phosphorous helps strengthen stems and produce flowers, and potassium keeps the root system healthy. In reality, these elements work in conjunction with one another. If you're applying fertilizer to tomato plants, for example, you're not as interested in the plant developing leaves as you are in it flowers and fruit, so you'd use a formulation lower in nitrogen and higher in phosphorous and potassium, such as a 5-10-10. Since phosphorous doesn't move as readily through the soil as does nitrogen, it's a good idea to mix a small amount (follow package instructions) into the hole before transplanting, or to mix it into the soil before sowing seeds. Add the fertilizer before planting, and then see how the plants thrive. You can add a sidedressing of fertilizer mid season if the plants look like they need it.

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