About Germinating Composts for Seeds

& making your own seed compost

You need to have good seed compost for success. Any old bag of compost won't do.
Multi-purpose compost is NOT the same as a germinating mix and in my experience won't do.
You have to be wary of earth with hard lumps of peat. That won’t do for seeds. You would expect proper seed soil to be fine and light throughout so, I for one, would ask for my money back if my purchased seed compost turned out with hard lumps.

As an organic gardener you might make compost for seeds out of leaf mold, sand, seaweed etc... You would need to have already made leaf mold or loam and liquid seaweed, and then buy the mineral components - sand or perlite or vermiculite, more on this below.
But you don't have to.

I never make seed compost from garden earth - you could try using loam if you've made some.

You can buy some excellent ready prepared seed compost for organic gardening by following this link. These organic mixes are good for any gardener who is sowing seed. The American germinating mixes have high approval ratings from the gardeners who use them. (You can also click through to U.K. composts from the above link.)

What Your Seedlings Need From Seed Compost

Sufficient Water
• to absorb from their surroundings,
• to protect the root tip and delicate root hairs from drying,
• to enable them to absorb nutrients,
Air
• to supply sufficient oxygen for active growth
Warmth
• to help them grow sufficiently strong and beat off attacking fungi,
All Major Nutrients In Smaller Quantities
• N.P.K. and Calcium in organic form, but never as fertilizer salts
Micronutrients
• New roots especially need micronutrients to make them strong and healthy and resist fungal attack.

Find The Right Balance For Seed Compost - water

There's a balance in soil between the content of water, air and heat. Too much soil water causes roots to suffocate through poor air supply. Such soils are cold, take a long time to heat up and loose heat quickly. But too dry causes the fine delicate roots to whither.

Larger non binding soil particles such as sand, grit, vermiculite, and perlite create larger air spaces which allow water to drain down. So the trick is to mix a material that includes well-drained larger spaces lined by moisture.

The best of both - moisture holding and well drained. However, for seeds and seedlings the balance favours good air-supply and warmth.

Mixing my compost at home is hazardous to success:- weed seed and disease contamination, the wrong mix, unbalanced organic fertilizers are significant problems. The mixes in my compost catalog are tried and tested, and better than any before.

Well watered compost of the right mix should always drain down to the ideal moisture content - well in theory. In practice it may take time. Nevertheless having the right compost mix takes some of the guess work out of how much to water. Try this link to find my seed composts
Also - check out seed propagators on this link - a water tray and capillary matting ensure seedlings won't dry out.

If you mix sand into compost make sure it is the right kind of horticultural sand. Builder's sand contains lime.

Find The Right Balance For Seed Compost - nutrients

Seedlings need all the major nutrients but only in small amounts. They are damaged by inorganic fertilizer salts. But organic fertilizers such as small amounts of fine bone meal or fine rock phosphate are beneficial. These should be mixed-in a month or so before the seed compost is used.

Phosphorus in particular supports a growing root's need for carbohydrate over that of top growth. Calcium which may be supplied in Gypsum or Bone Meal has to be present for the plant to make cell walls. You can expect die-back and disease if it isn't.



Some seed compost mixes - which by all accounts are very effective - include protein meal.

Micronutrients are also essential and should be included in organic material to strengthen the roots so they resist fungal attack. Seaweed solution is ideal.

Inoculation with suitable beneficial micro-organisms is another way to give some plants a head start.

Of course seedlings also need to be well-light all around. Otherwise they grow toward a single light source e.g. a window, and may grow long and leggy. There's more information on suitable supplies on these links... catalog page America, catalogue page U.K.

Check these links too.

Next   >  How to start seeds in propagators  -  match your method to your plant & garden needs for an earlier start & better results...

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The Garden Seat - books by experts to help you grow garden seeds

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The main plot for information on seeds and seed sowing   on this link includes:- planning your seed site & sowing seed, making a seed bed, saving seed, seed compost, growing flowers and vegetables from seed, using: modules, root trainers, deep fiber pots, propagators, ... ... ...

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