Tony Dickerson answers your questions
QAre there any regulations covering seed quality?
ABrian Ayling, Perth, Scotland
The seed quality of economically important crops (vegetables and grains) is regulated by law in most countries, including the UK. Only certified, tested seed can be legally sold and only by licensed suppliers. Seeds of ornamental plants are not covered by official seed quality schemes but, like any other goods, are covered by consumer protection law.
Most vegetable seed grown by gardeners is covered under law, including that offered by the major seed companies. Only varieties on the ‘approved list’ can be sold, although there are special, more relaxed, approval conditions for garden varieties. Many readers will be familiar with small, family businesses offering, in particular, seed they produce and gather themselves, often covering many of the heritage varieties not offered by the big seed companies. For the big seed producers, seed must be grown well away from similar crops to limit cross pollination, be true to type, officially inspected in the seed field, and have below specified limits for weed seeds. They must also meet minimum laboratory germination requirements that range from 65 per cent for the notoriously difficult carrots and leeks to 80 per cent for peas and sweetcorn. Real-life field or garden germination rates will be much lower of course, so allow for this when sowing. Having said that, most gardeners probably sow too thickly most of the time. Seed companies usually look sympathetically at cases where the seed appears to fail. Often, however, this is due to sowing too early, perhaps without adequate light and heat. Sowing too thickly or overwatering may also lead to damping off.
For vegetable crops, the seed packet recommendations for sowing distances in rows and between rows are usually those that commercial growers would use to achieve vegetables of a certain uniform size and quality for marketing. For the gardener, sowing closer will generally result in smaller vegetables but if you want king-size vegetables they will need more space.
Some seed packets are hermetically sealed and the contents may keep for an extended number of years. Generally, it makes sense to buy just enough seed and sow it well before the expiry date given on the packet. In the case of difficult to germinate varieties, it pays to buy fresh seed each year regardless of the packet date.