Recipe for a complete organic fertilizer
I've been using this recipe, which is the one Territorial Seed Company used to recommend back when Steve Solomon owned the company, with good results since 1993. Unfortunately Territorial no longer includes this recipe in their seed catalogs, so I'm posting it here because I believe it to be important information for the maritime Pacific Northwest home gardener.
One word of advice: Instead of buying the components in small boxes, buy them in bulk whenever possible (see "Where can I buy the components?", below). As long as you keep them these ingredients dry, they will last for years.
All measurements are in terms of volume, not weight.
- 4 parts seed meal
- 1 part dolomite lime
- ½ part bone meal
- ½ part kelp meal
This component provides nitrogen, with smaller amounts of phosphorus and potassium. I like to use cottonseed meal or alfalfa meal, both of which are relatively inexpensive and readily available. Of the two, cottonseed meal provides more nitrogen; but it is somewhat more expensive. Additionally, in some states cottonseed meal is reportedly not allowed in a certified organic operation (although that's not something that affects most of us). Another seedmeal option is rape/canola meal.
In spring I like to substitute blood meal in place of some seed meal, since blood meal is somewhat faster acting. You could try using three parts seed meal and one part blood meal. What I usually do, though, is leave the fertilizer recipe unchanged but add blood meal separately at sowing time.
Seed meals tend to be acidic, so lime is included to balance that out. Dolomite limestone is roughly half magnesium carbonate and half calcium carbonate. Calcitic limestone is pure calcium carbonate. Plants usually need more calcium than magnesium; so, if you want to be really tricky, use 1/3 part dolomite lime and 2/3 part calcitic lime. I use dolomite in the fertilizer mix, then use calcite when I lime my beds each fall.
If your soil is alkaline, you might experiment with reducing or eliminating the lime in this mix.
This makes up the bulk of the phosphorus component. While the original Territorial recipe lists soft rock phosphate as an alternative source of phosphorus, I prefer bone meal. Not only is bone meal easier to find than rock phosphate, it also is already being produced as a byproduct of the beef industry. Rock phosphate is mined.
Less bone meal is required since it releases its phosphorus more readily. The advantage of using rock phosphate is that it continues to contribute phosphorus to your soil over many years. If you choose to use it, double the amount - use one part rock phosphate.
Kelp meal contributes potassium and also many micronutrients. This tends to be more expensive than the other components, and harder to find in bulk. Fortunately you need less of it than the other materials.
Another possible potassium source is Jersey Greensand. It has the same advantages and liabilities as rock phosphate (its very slow release). In addition, it does not supply micronutrients.
How Much Do I Use?
I often get e-mails that say "Great recipe! But how much do I spread in my garden bed?". There is no single answer that fits all situations, because different plants have different nutritional requirements. It also makes more sense in many cases to fertilize plant by plant, instead of broadcasting it into the entire bed. If you want to know how much I use for the various vegetables, check out my FAQ on Maritime Vegetable Culture. This recipe will also work for ornamental plants, and even for lawns; but I haven't developed guidelines for those uses.
Where can I buy the components?
Whether a particular business sells any or all of these components will vary from year to year, unfortunately. Check with local feed or farm supply stores first. I've occasionally had luck finding bulk bags at plant nurseries. If you live in the Puget Sound region, consider checking your local McLendon's Hardware. In my experience they usually carry most of these products in mid-size bags - 20 pound bags of cottonseed meal and (sometimes) kelp meal, 20 pound bags of bone meal, and of course 40 pound bags of both dolomite and calcite lime. They're only a couple miles away from my place, so usually I go there first. Note that kelp meal is getting harder to find in bulk packages.
When possible, I purchase certified organic versions of all these products. Philosophically I prefer to support organic agriculture; but, more specifically, I have concerns about certain practices in the beef industry - so I always buy organic bone meal nowadays. Even so, wash your hands after handling any bone meal.
If you want to learn more about these components - to discover their typical NPK values, for example - Colorado State University has an informative pamphlet available online: Organic Fertilizers, publication 234.
A recent email let me know about a 2006 article Steve Solomon wrote for Mother Earth News. While his recipe is still similar to the old Territorial formula, he has made some changes. He substitutes gypsum for some of the lime - I would not recommend gypsum for the maritime Pacific Northwest since the calcium is bonded to sulfate, which may actually increase the acidity of your soil (counteracting the calcium's effect, in other words). He's also doubled the bone meal component, but without doubling the alternative rock phosphate (which is rather odd). Note that Steve lived in Tasmania at the time the article was written, and as such may have tweaked the formula to better match his local growing conditions.
The specific list of fertilizer components and amounts on this page is exempted from my copyright notice - it's not possible to copyright a list of ingredients, and the recipe itself is not original to me in any case.
I would like to thank Tim Peters, then (back in the early 1990s) lead plant breeder and trial grounds manager of Territorial Seed Company, for answering some of the "why" questions I posed to him regarding the recipe.
All contents © Travis Saling
This page was last updated November 18, 2013