Tips for Tomato Seedlings

For many tomato growers, spring is the time of year when every available windowsill is filled with tomato seedlings!

The thing is, it’s very easy to pamper them too much and kill them with kindness! Here are a few tips for tomato seedlings that can help keep them healthy and vigorous.

How To Water Seedlings

Seedlings up to four weeks
In the first few weeks it is very important not to over-water seedlings. They will develop a better root system if they are slightly under-watered and encouraged to search for water with their roots.

Seedlings over four weeks
Transplant seedlings after around four or five weeks to their own small pots.

If you add perlite to the mix, you can water from above as there is no chance of compaction and removal of air.

Tips for Tomato Seedlings

Watering, Compaction and Air
If you are growing in seed compost or potting compost only, it’s a good idea to water from below. It’s also a good idea to allow compost to dry slightly to get plenty of air back into the root zone as the soil dries. Obviously, never allow soil to dry-out completely.

Over-watering will reduce air in compost, slow plant growth and poor root development and possibly cause root disease.

By allowing compost to dry-out a little before transplanting, helps to make the soil lighter and roots less likely to break when moved.

Feeding is Unnecessary
There is enough food in seed and potting compost to feed seedlings.

Media Without Nutrients
However, if you are growing in sponges or some makes of pellets/plugs, you will need to feed your seedlings with First Feed or 25% to 50% dilution of a general feed such as Miracle Grow.

Cause of Failed Germination
Sometimes a whole tray of seedlings will fail to germinate. At this time of the season it is probably because of wide ranging temperatures, and in particular, it’s too cold at night.

Tomato plants grow at their best rate when temperatures don’t fluctuate too much. Keeping the temperature within a specific range (15 to 21C is good depending on available light) but this is almost impossible at this time of year for the home-grower, unless a lot of money is spent of course!

Avoiding Leggy Seedlings In Cloudy Weather

  • Give them as much light as possible – use reflective white     sheeting/paper
  • Reduce watering
  • Keep temperatures from becoming too high to help prevent legginess

Some varieties are prone to becoming leggy – Red Alert for example, and some will remain stocky even in cloudy weather – Tumbling Tom for example. However, most varieties will become leggy without enough light.

Two conditions seedlings hate

  • Damp air – especially when it’s cold
  • Saturated roots

Propagators with hoods
If you are using a propagator with hood, open the vents and remove the hood as soon as the seedlings germinate. This will help to reduce the threat of fungal disease and “Damping-off”. This didease is caused by fungal spores and damp conditions.

As long as seedlings are indoors, cold weather isn’t too bad for growing tomatoes as long as there is plenty of sunshine through the window!

Of course, plants need to be kept indoors – especially at night or in a heated greenhouse. However, during the day a sunny windowsill or a day trip to the greenhouse, polytunnel or a few hours on the patio, as long as there is no wind, will do them good!
See Also:

How To Grow Tomatoes From Seed
Tomato Seed Choice 2018

Watering Tomato Seedlings
Feeding Tomato Seedlings