How to start seeds indoors

Tomatoes, peppers, many flowers and herbs need a long season. By sowing them indoors in late winter, they are strong young plants when the weather is warm enough to go outside. Here is how to do it.

What you need

• the windowsill propagator,
• the seed trays, 5 pieces,
• seed compost, which is finer and lighter than normal potting soil,
• seeds,
• a shallow tray for water,
• labels and a pencil.

When to sow

• February to March: tomatoes, peppers, chilies and eggplants.
• March to April: lettuce, cabbage, leeks and most summer flowers.
• April: basil, zucchini, pumpkin and beans.

The seed packet always tells you when and how deep.

Step 1: fill the trays

Fill the cells of the seed tray with seed compost. Press it down lightly, so there are no big air pockets, and level it off.

Step 2: water from below

Place the trays in a shallow tray of water for ten minutes. The compost soaks up water through the holes in the bottom. Watering from below doesn’t wash away the seeds, and the surface doesn’t form a hard crust.

Step 3: sow

Put one or two seeds in each cell. Large seeds go about one centimeter deep. Tiny seeds, like lettuce, lie on the surface with a thin layer of compost sprinkled over them. Write a label for every row. You will not remember which tomato was which.

Step 4: cover and keep warm

Put the trays inside the windowsill propagator and close the dome. The warm, humid air makes seeds germinate up to two weeks earlier. Place it on a light windowsill, but out of fierce midday sun.

Step 5: air and light

When drops form on the inside of the dome, open the vents a little. When the first seedlings appear, open them further. Turn the propagator a quarter turn every day, so the seedlings grow straight instead of leaning to the light.

Step 6: thin out

When two seeds came up in one cell, cut the weaker one off at soil level with small scissors. Pulling it out can damage the roots of the other.

Step 7: get them used to the outside

Two weeks before planting out, put the trays outside during the day in a sheltered spot, and bring them in at night. This is called hardening off.

Step 8: plant out

When the nights stay above about ten degrees, plant them out. Push a pencil through the hole in the bottom of each cell, and the plant comes out in one piece. A raised garden bed, cedar wood, filled with compost and garden soil is an ideal home for them.