Starting from seed

Growing from seed is slow but rewarding, and it is how most herbs and vegetables for a balcony begin.

Use clean containers and a fine, light seed-starting mix, not garden soil. Sowing depth matters: Iowa State Extension notes that seeds sown too deep may never emerge. Fine seeds, and seeds that need light to germinate, go on the surface and are pressed in lightly. Larger seeds are covered to about one to two times their own width. The seed packet usually tells you which.

Cover the tray with clear plastic or glass to keep moisture in until the seeds sprout. Most seeds germinate when the mix is between about 20 and 30 °C,.

Once seedlings appear, remove the cover and give them plenty of light. Seedlings on a dim windowsill stretch into weak, pale stems; extension advice is 12 to 16 hours of light a day, and under lamps the light should sit about 10 to 15 cm above the seedlings. Water when the surface just feels dry, and keep air moving, because soggy, crowded, stuffy trays invite damping-off, a disease that makes seedlings collapse at the base.

Move seedlings into their own pots when their first true leaves appear.