Windowsill gardening

My study windowsill, with tomatoes and sweet peas.

Got an unused windowsill that gets plenty of light and is draft free? If it's not full of trays propagating seeds or cuttings you're missing out. You just wouldn't believe how many plants you can raise from such a small space!

It's really easy to grow plants from a windowsill, giving you a head start in with vegetables or flowers in the garden or allotment. Here's how to raise seeds. Also works for cuttings, though you should use plant pots rather than seed trays.

What you need

1. A draft free windowsill that gets at least five hours of light each day.

2. Trays that fit the windowsill and hold water.

3. Smaller seed trays with watering holes in the bottom, that fit inside the watering trays. 

4. Standard seed compost.

5. Vermiculite.

6. Plant tags

How to plant

Mix compost and vermiculite. I generally use a small handful of vermiculite to a large two handed helping of compost. The vermiculite helps to keep the compost light and airy and aids watering.

Fill the seed trays with the mixture. Follow the instructions on the seed packet for planting. For example, with small seeds such as tomatoes I make four shallow drills running lengthways and carefully place individual seeds along the drills, leaving a small space between each. Cover the seeds and label the variety with a tag.

Some seeds, such as begonias or Livingstone daisies, need light and should be sparingly scattered on top of the compost, covered with a plastic freezer bag and kept moist.

Aftercare

Besides being draft free, the windowsill needs to reach the required germination temperature indicated on the seed packet at some point in the day, although you don't need that temperature all day. Lettuce and spinach will germinate even if the minimum temperature drops to near freezing, but the germination rate for all plants will be affected if the temperature drops below 40ºF. Ideally keep the minimum temperature above 50ºF.

Some of the tomato seedlings repotted, 150 from a small windowsill!

Unless the packet instructions indicate the soil needs to be kept moist, allow the compost to almost dry out before watering. If you lift a seed tray up it should feel quite light. To water, fill the watering tray to half an inch of water so it can soak up into the seed tray from the bottom. Don't overwater; if you do the compost may become musty.

Once the seedlings appear, turn the tray around each day so the seedlings don't get too leggy and bent towards the light.

Planting out

Generally you can replant the seedlings once they grow their second set of leaves.

If the plants are sun loving varieties such as tomatoes, peppers and cucumbers, you'll need to transplant into pots and grow on in a greenhouse or shed with plenty of light until all risk of outside frost has passed. If to be transplanted in the ground, acclimatise the plants first by leaving outside on a warm day, gradually increasing their time outdoors.