How to Sow and Germinate seeds

leggy tomato seedling

Using seed can be an easy and cheap way to grow your own flowers and veg. If you are growing vegetables from seed you can pick varieties you like and also get a head start on the growing season, by early sowing such as cucumbers, courgettes and other vegetables in February. 

To germinate and grow well, seeds need a controlled environment with as much light as possible. The light is as important as warmth /being frost free which is why sowing early in the year is more difficult when light levels are low. If you sow veg in February/March, you will also need somewhere frost free and warm for the seeds to grow  and unheated greenhouse is likely to be too cold at this time of year. It is a balance; sow too early and the seedlings may struggle and be leggy, too late with some crops such as sweetcorn and tomatoes you may struggle to get a decent crop before the Autumn arrives if we have a  bad summer or you garden in an exposed area.

Video advise on how to sow and germinate seeds.

Tips to the best from your seeds:

Here are some ideas on how to ensure  sucessfull germination.

  1. Give last year's seeds a go as many seeds will keep well over the winter and be viable in the spring, except carrot seed. If you sow old seed early and germination fails, sow again with fresh seed.
  2. Ideal conditions are clean containers, a multi purpose compost which has been gently watered before sowing. It is best to water first because watering after sowing can cause the seeds to move, so they are uneven and also come to the surface. Do not let the compost dry out after sowing/germination water from the base by standing in a container.
  3. Early in the season compost can be very cold having been stored outside for several weeks. Bring the compost into the garage, greenhouse or conservatory to warm up for early sowings.
  4. Sow into individual pots or trays checking the seed packet for the sowing depth because not all seeds are sown to the same depth. Don't mix seeds in the same seed tray because they will germinate at different times, which will cause a problem if you are sowing early in the year and using a propagator, (as in, you cannot take half a seed tray out of the propagator.) 
  5. If you are sowing members of the bean family (peas, runners, broad or French beans) sow in a deep container as they need a long root run. You can use loo roll holders illustrated above, take care when watering not to saturate the tube.
  6. If you are sowing early in the year the seeds somewhere warm to germinate, a sunny windowsill or conservatory are ideal and a heated propagation mat is a great help. 
  7. Most seeds like a warm temperature and slightly damp environment to start them off and a propagator is ideal. If none is to hand, use a polythene bag secured tight over the pot. (elastic bands are ideal) to create a closed environment; a good tip is to put a stick in the pot which holds the bag away from the emerging seedlings
  8. Once the seedlings have emerged take out of the propagator or remove the bag. This is because if the seedlings remain in the warm muggy atmosphere they will become soft and sappy (see image below) which does not make for good plants.
  9. Light is crucial; if growing in a room where the light is predominantly from a source so on one side, such as a windowsill, porch , conservatory, it is important to turn the pot regularly, ideally every day, otherwise the seedling becomes spindly. If this occurs, repot the seedling  burying  it deep with a good bit of the spindly stem in the pot under the soil level,  and it will grow on well as shown in the images below.
  10. There is a big difference at which temperature seeds germinate, for example lettuce will germinate at 5C, whereas runner and French beans, and sweetcorn need 15C, as do courgettes and cucumber, (although greenhouse varieties need at least 21C).  Broad beans and most Brassicas will germinate at 8C, Carrots 10C and chilli and squash a whopping 21C. Bear this in mind in terms of early sowing when it is cooler, a good start maybe lettuce and broad beans.


    In the images below, seeds are being germinated in a propagator and the water droplets  are visible which shows the atmosphere created which is ideal for germination. It is important to remove the seedlings from this atmosphere as this, or a lack of light, can cause seedlings to grow as in image 2 in the centre. This may not be fatal if it is not too bad, pot on the seedling as in image 3 and you can see much of the spindly stem has been buried, and it will grow on to be a sturdy tomato plant.

What to do if seeds do not germinate?

What if your seeds do not germinate?  it may not be your fault, here's why. The video explains but the short answer is the  EU regulations governing seeds which set out minimum standards of germination for commercially sold seeds.

So for example, Carrot seed, which are one of the most capricious when it comes to germination, the EU regs specify a minimum germination of 65%, and the same for Leeks, but for cucumber and runner beans it is 80%. Maybe I am slow, but I had assumed that all seeds were near to 100% good to germinate, as sold, clearly not.

"Which " that great champion of consumers surveyed this  problem and found, back on 2007, some bad offenders amongst our well known seed retailers, with some as little as 2% viable seed which went on to germinate. "Which" revisited the issue 2 years later and still many seed companies were still not reaching minimum standards. Hopefully seed retailers have improved further since that bad publicity.

Rather surprisingly there are no minimum standards for flower seeds at all. So take heart if your seed doesn't germinate it maybe nothing to do with your green fingers. 

Seeds in Propagator

A propagator creates a warm moist atmoshphee

Leggy tomato seedlings

seperate leggy seedlings

Leggy seedling planted deep

plant the leggy seedling deep