If you’ve tried starting seeds on a window sill inside, you might have found that they grow thin and weak looking?
If so, this is a common issue, particularly in urban areas. Surrounding buildings or trees cast shade, reducing the light. This creates a problem if you’re trying to raise seedlings inside as they need plenty of light to thrive.
Affect of temperature
Seedling growth is also affected by temperature. The warmer your home is, the more light your seedlings will need. So a warm home that is not very bright will be the most challenging to raise healthy seedlings in.
Four ways to get more light to your seedlings
The best strategy depends in part on whether you want to start ‘tender’ or ‘hardy’ crops from seed.
Tender crops include tomatoes, chillies and aubergines – these do not grow well in temperatures below 10 degrees centigrade (50 Fahrenheit) and are killed by frost.
More hardy crops include leafy veg like kale, rocket, and most Asian leaves, root crops like beetroot, turnips and carrots, and peas and broad beans. These can survive colder weather once established, but a hard frost when they are tiny seedlings can be fatal if they are not protected in some way,
1. Wait until it’s warm enough to sow outside
This is the simplest and easiest solution. For the more hardy crops it’s also a very good solution. You can sow these outside about a month later than you could inside – but they’ll still have plenty of time to grow and do well. This is also a good solution for tender crops like courgettes and runner beans – as these need a shorter growing season than aubergines and chillies. Starting these outside in late April or May is fine. But it’s not so good for tomatoes, aubergines and peppers. If you wait to sow these outside, you may not get a crop at all.
2. Get a small greenhouse or cold frame.
This will enable you to start your seeds a few weeks earlier than you could by sowing them directly outside. For tender crops you should keep an eye on the weather forecast, moving them inside on cold nights.
3. Start your seeds inside and move outside on warm days
Moving your seedlings outside – even for a few hours – can dramatically improve their health, as long as the temperature difference is not too great and the seedlings are reasonably well protected. A simple and effective way to protect them is to use a propagator with a plastic lid. This will help insulate the plants from the cold and protect them from the wind. Be selective about which days you move plants outside on, choosing the warmer days. And don’t forget to bring them in again at night!
This strategy works really well for the more hardy crops listed above. (It’s my own preferred option). You can also use it successfully for the more tender crops – you just need to be more selective about which days you move your plants outside. Even a few hours of bright light a day will make a difference.
4. Invest in a propagation light.
If you’re serious about growing chillies, peppers and aubergines, you could consider investing in a propagation light. Energy efficient, compact fluorescent bulbs, are now available, delivering the necessary wavelength of light (you want ‘blue light’) for seedlings.
I’m trying one for the first time this year. It’s a bit early to pass judgement but so far the tomato seedlings are doing well.
Or, you can simply buy the plants
As you’ll have gathered, it’s the tender plants that also need a long growing season, like chillies, that present the greatest challenge. Another excellent solution is simply to buy these as plants later in the year.
Look out for local community plant sales: a great place to buy good value plants and to meet other growers in your community at the same time.