Alison Swanson of the Scottish Allotments and Gardens Society gives advice on successful seed sowing

Spring into seeds
Spring should herald a seed sowing frenzy. New plotters sometimes worry about this, perhaps doubting a handful of grains will survive and grow to maturity on the wide open allotment. But such worries are unfounded. Seeds are an amazingly easy and cheap way to grow lots of food, and those who save their own seeds can do it for free.

The key to success with seeds is creating favourable conditions for germination, the magic that happens when seeds split open and burst forth into life. Sow them in a suitable growing medium, such as soil or compost, water well and avoid sowing in extremes of heat or cold.  For example, warm spring sunshine is good but hard frost is bad. It is also important to have plenty of daylight. With only a few exceptions, germination happens under the soil surface in darkness but your seedlings need light to photosynthesise and survive. Light starved seedlings are leggy and tall, have thread like stems and fall over, whereas good light conditions produce healthy, fat and stubby seedlings.

Buried treasures
Seeds are actually tiny little embryos wrapped up with food, in the form of starch, to sustain their first growth spurt. Bigger seeds like broad beans (Vicia faba) contain more food and have greater “oomph” to push up through the soil whereas smaller seeds don't  A useful maxim is therefore to: sow big seeds deep and little seeds shallow. A planting depth of around two times the size of your seed works well.  Lettuce (Lactuca sativa), summer savory (Satureja hortensis) and dill (Anethum graveolens) are examples of the tiniest seeds to be sown on the surface as these require light for germination.

Scottish Gardener:

Sowing outdoors
Most outdoor crops like beetroot (Beta vulgaris), early turnips (Brassica rapa subsp. rapa), scorzonera (Scorzonera hispanica) and spinach (Spinacia oleracea) work well when sown from around March to July. This is a safe window for favourable temperatures, light levels and moisture but extra watering may be required in dry weather. A nice trick is to water the ground before sowing to avoid losing small seeds in a post sowing deluge.  Carrots (Daucus carota subsp. sativa) in particular like this treatment. In good conditions it might be possible to start sowing earlier than March but extended periods of cold and wet carry the risk of seeds being waterlogged and rotting. A second time window opens from mid-summer to autumn when oriental vegetables, who thrive on being late to the party, can be sown. Good examples are Pak Choi (Brassica rapa subsp. chinensis), chinese cabbage (Brassica rapa subsp. pekinensis), Konmatsuna (Brassica rapa subsp. perviridis), but there are many others.

Sowing indoors
The fun from seeds is increased tenfold by erecting some form of plastic covered shelter for tender crops like tomatoes (Solanum lycopersicum), peppers and chillis (Capsicum annum), aubergines (Solanum melongena) and cucumber (Cucumis sativus). These can also grow really well outdoors but its slightly more tricky and their seeds must be germinated in warmth.  The sun beaming through clear plastic works perfectly and an ideal temperature is around the mid 20’s Celsius.

Damping off
The renowned conservationist Thor Hanson recounts an experiment where he tried to break open a seed with a screwdriver, a pipe wrench and a hammer. The seed wouldn’t yield and he eventually resorted to brute force, a mallet and a rock chisel to achieve this end. It tells us two things. Firstly, that conservationists might be scarier than the allotment committee and secondly, seeds aren’t completely indestructible. Rock hammers are few and far between on allotments but pathogens, the scientific catch all for unspellable viruses, bacteria and moulds, can mysteriously kill healthy seedlings overnight. The sudden sickening is often called “damping off”. Washing all seed trays and pots regularly and ensuring plenty of airflow is the best way to avoid most diseases. In olden days gardeners would squirt a substance called Cheshunt compound, aka the irritant copper sulphate, around liberally as a preventative but this has rightly been banned. 

Opening packets
Some people can develop a bit of an obsession with seeds. Usually this is manifested in hoarding behaviour with the afflicted storing masses of colourful packets in cupboards or under the stairs. The cure for the obsession is simple, get out there and sow.