In perfect conditions seed germinates well, so let’s look at how to make those conditions. Top requirements are healthy soil and healthy seed.
Your soil should be able to both hold water and allow excess to drain. The seed needs water and air to germinate successfully. The best vehicle for good water retention and drainage is organic matter, and having plenty in the top inch of the seed bed is important.
Organic matter in the soil is helpful in every respect, and it is good to add a good dose as often as possible. My own method is to put an inch on the surface of the soil in the summer when the plants are well established. I do this even with carrots and parsnips, and it does not make them fang. If you dig your compost in, it will disappear to a depth where the plant can only reach it when its roots and the mycorrhizae get to access it. The next winter, though, you may dig a little of it back up to the top again.
On the subject of digging, experiments have shown that this makes seedling establishment slower than in undug soil. It is probably the result of disruption to all the soil fauna and destruction of precious soil structure.
A fine tilth helps. This means lots of tiny crumbs of soil which can surround the seed with water but not exclude air needed by the seed to breathe. My own soil is naturally crumby because of all the organic matter in the topsoil, but you may need to gently work the soil with a hoe or rake to get those crumbs right. Remember that disturbing the soil encourages weed seeds to germinate. If you have a fine tilth, you can gently firm the soil over the seed without smearing it. As a rule, gentle watering firms soil crumbs around the seed for you.
The depth of sowing is generally in proportion to the size of the seed. So potatoes at 4”, beans at 2”, sweetcorn at ¾”, carrots at ½” lettuce at ¼” and celery on the surface. Keeping the seed moist is crucial while they have no roots, so the water retention of organic matter is helpful. In dry windy conditions like last spring, we watered our carrots three times a week and scored 100% germination. If overwatered, any inadvertent excess would drain away in the crumby topsoil. Sowing in April showers does the work for you with shallow seed sowings, but beans should not need watering at their 2” depth.
Celeriac, which takes 2 to 3 weeks to germinate and has to be sown on the soil surface, is best raised in modules or seed trays, with glass over the surface to retain moisture and also see when to take the glass off as the leaves emerge.
Seed quality is a big subject! Most of the big seed companies inevitably get themselves into a hole occasionally due to bad weather, buying in seed from outside or from having to use old seed. Your own seed is best, and helps you realise it is difficult to do!
My experience is that you need new seed each year for parsnips, followed closely by carrots and sweetcorn. Many others will keep well for a few years if you store at consistent levels of low humidity and temperature, which is also difficult to do. Whatever you do, don’t keep your seed packet outside in a shed.
And slugs, I hear you ask? Keep all weeds at bay all winter, as that is what makes slugs grow strong. And don’t use slug pellets, all the things that eat slug eggs eat and die from the pellets too, and the problem gets worse. I have proved it several times to my cost, and no longer use them. And what did the slug say as he slipped down the wall? How slime flies!
The last word is to sow at the right time. If sowing early, used fleece to warm the soil, but the seed can only germinate if it has the warmth it needs. This month’s joke is in the middle of the article, so you must read it all!