So just what did I do wrong in the vegetable garden!? Some years, try as we might, doing everything by the book, things seem to conspire against us. At other times our plants either fail to germinate at all or have got off to a good start then all of a sudden they just wither and die without warning. Of course pests and diseases can be an issue but these are covered elsewhere on the web. Instead here I’ll try and address some of the things we may have done wrong ourselves and how we might get it right next year.
There are countless reasons why your seeds may not germinate with temperature, water and viability being the major three.
Seeds too old/not viable
Always check the sow by date on the back of the pack before you sow. If they are saved seed look up how long the seed should last (there is a handy chart in my book, Grow your food for free, published by Green Books. Even if the seed is out of date you can do a quick germination test by putting a 10 seeds on a wet piece of paper towel and counting how many sprout. If you have 5 sprouting then you can expect 50% germination, just 1 and only 10% will germinate.
Wet or cold soil
Early this year (2013) we had a very late spring, it was cold then wet and pretty miserable. If the soil is too wet or too cold, seeds can fail to germinate and eventually rot. To prevent overly wet soil, plenty of compost should be added at the time of planting. Although the composting material is usually under the area you sow into, creating a bean trench can be enough to loosen and aerate the soil and prevent rotting.
Black plastic sheeting can heat the soil up a degree or two and this can aid germination as can sowing into a cloche. If a packet says ‘sow March’ but the soil temperature is near to freezing in March then nothing will germinate. I took the very useful chart below from an obscure website . It illustrates why things like Aubergines need the extra heat of a green house or heated propagator.
|0-25 °||Cabbage lettuce||5 ° +|
|0-29 °||Crisphead lettuce||5 ° +|
|12+ °||Sweet corn
|5-32 °||Broad bean
Broccoli / Calabrese
|8 ° +|
|13 ° +||Courgette
|15 ° +|
|15 ° +||Pepper (capsicum)||21 °|
|7 ° +||Beetroot
|10 ° +|
|7-21 °||Chinese cabbage
|12 ° +|
|18 ° +||Celery (golden self blanching)
|21 ° +|
|21 ° +||Aubergine
Indoor sowings or using a heated propagator can give plants a good start and ensure an even germination. Plants can go through what’s known as planting ‘check’ when they seem to struggle not long after re-planting. Most will bounce back but it is a good idea to harden off seedlings before planting them out.
To harden off a seedling, put it outside during the day and bring it in at night for around 2 weeks before planting in its final position. Alternatively start plants off in a cold frame, opening the frame in the day and closing the top at night.
I may be acting like an old man by repeating this story but it does always spring to mind when I think about problems with seed sowing. While planting peas and beans on my Bristol allotment I was dismayed to find very few of them germinating. I was at a loss to what was going wrong. I soon found my culprits in the nearby population of large, intelligent birds, such as magpies and crows. They would watch me sow each seed, memorise its whereabouts before swooping down for an easy free meal. After that I decided to sow my beans in the safety of my bay window before planting them out as seedlings. You could also net the seeds to prevent birds swooping in. In my experience nets are far more effective than putting up ‘bird scarers’ such as old CDs or bits of foil. Mice and rats can also be problematic with larger seeds and if yours have vanished look for tell-tale droppings.
Broad leaf plantain can be a sign of overly compacted soil. All seeds will find it hard to germinate in this kind of ground but peas and carrots will especially struggle.
If the soil is made up of large clumps the roots cannot make contact with the soil surface. If this happens a plant won’t get the nutrients it needs and it will wither and die. Clumps can form from working the ground when it is too wet or from insubstantial cultivation. Clumps should be broken up with a spade, the back of a fork or with a garden claw. Again add plenty of organic matter to ensure the soil is aerated and has a workable texture.
|Crop||Common reasons for no germination|
|Peas, Beans and Corn||Compacted soil, birds or small mammals eating seed, wet soil, cold soil (corn)|
|Carrot||Compacted soil, old seed|
|Lettuce||Slugs, chunky soil preventing root contact|
|Squashes||Seed rotting in wet soil, Slugs eating seedlings|
|Tomatoes, Aubergines, Chilli||Too cold, seed sown too deeply|
|Cabbage||Seed sown too deeply, Soil not properly cultivate (too chunky or compacted)|
Planted too deeply
If you have no frame of reference then who’s to say how deeply something should be sown? It is easy for new growers to bury seed far to deeply making it have to work that little bit too hard in order to push its emerging shoots through the soil. To prevent this as a rule of thumb a seed should be planted no more than two to three times its size. Some smaller seeds won’t need covering at all but a dusting of soil or compost sometimes helps.