How to give your seedlings the best start

Lettuce, spring onions, spinach and coriander on March 1st 2023

For seeds to germinate you need: Good soil - viable seeds - the right temperature - moisture - lots of light.

Sounds simple enough, but sometimes seeds don’t germinate, they germinate and die or become leggy or the leaves turn yellow. Don’t despair, read on!

Seed compost

Germinating seeds are prone to moulds or funguses or larvae in compost that is old or stored damp. We suggest to always use new sterile seed compost. You can sterilise old compost in the oven for 30 minutes at 150 C.

Seeds

Always use new seeds and check best before date, if you save seeds yourself, harvest from the best healthy plants. Store seeds cool and dry. If in doubt do a germination test. (See newsletter

Temperature

Seeds have an ideal germination temperature and if you can provide that, they reward you with good germination and speedy growth. Tomatoes, peppers, aubergines need 20-24C, cucumbers 22-28C, french beans 20C, cabbage, beetroot, lettuce 16-20C Providing the ideal temperature is nearly impossible to achieve without a heated mat, pad or propagator.

Light

Some seeds need light to germinate like celeriac, lettuce and basil and are only lightly covered, others need to go down like cucumbers, squash, beans. As a rule of thumb: the size of the seed determines the depth at which they are sown. Common mistake is to sow small seeds too deep! Once seeds have germinated they need as much light from above as possible, windowsill is not good enough!

Damping off

is caused by a fungus or mould that thrive in cool, wet conditions and affects many young vegetable and flower seedlings. Avoid overwatering.

Yellow leaves

The first two germination leaves or cotyledons will turn yellow or even fall off, but if the real leaves turn yellow it could bee overwatering, but most likely lack of nutrients, switch to potting compost, which has a higher nutrient content than seed or tray compost.