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Basil

The herb that makes a summer tomato taste finished, and it grows on a windowsill.

1. Sow indoors at 20 to 25 C, barely covering the seed.
2. Prick out into individual 9 cm pots at the second true leaf.
3. Wait for settled warmth before moving outside, cold nights stop it dead.
4. Plant 25 cm apart in the sunniest, most sheltered spot you have.
5. Pinch the growing tip above the second leaf pair once the plant is 15 cm tall.
6. Keep pinching every stem back to a leaf pair, which doubles the branches each time.
7. Remove every flower bud the day you see it, flowering ends leaf production.
8. Take a full cut in early autumn before the first cold nights.

Soil

Free-draining soil with compost, pH 6.0 to 7.0.

Sun

Full sun, 6 to 8 hours. It sulks below 15 C.

Water

Water in the morning at the base, keeping soil damp not wet. Wet leaves overnight cause rot.

Spacing

25 cm apart, rows 30 cm

Depth

0.5 cm deep, barely covered

Care

['Never water in the evening, damp cool leaves are how basil dies.', 'Feed a weak balanced feed fortnightly if in a pot.', 'Take cuttings in August, they root in water in 10 days for winter windowsill plants.', 'In Mediterranean heat give afternoon shade and it stays tender for longer.']

Harvesting

Pick whole stem tips, cutting just above a leaf pair, rather than stripping individual leaves. Take up to a third of the plant at a time. Morning picking gives the strongest aroma.

Storing

Do not refrigerate, the leaves blacken. Stand stems in water on the counter for 5 days. For winter, blend with oil and freeze in cubes, or dry, though drying loses most of the flavour.

Grow it next to

Tomatoes, peppers and aubergines. It genuinely deters some insects near them. Keep away from rue.

Problems

[{'cause': 'Cold nights below 10 C or evening watering', 'fix': 'Bring it in when nights cool, and water in the morning at the base only.', 'symptom': 'Leaves blacken and collapse'}, {'cause': 'Never pinched', 'fix': 'Pinch the tip at 15 cm and remove every flower bud as it forms.', 'symptom': 'Tall leggy plant with flowers on top'}, {'cause': 'Botrytis in crowded damp conditions', 'fix': 'Thin to one plant per pot, improve airflow, and remove affected stems.', 'symptom': 'Grey fuzz on stems and leaf drop'}, {'cause': 'Basil downy mildew', 'fix': 'Remove and bin affected plants, space widely, and grow a resistant variety next time.', 'symptom': 'Yellow patches on top and grey mould beneath the leaf'}]

Saving your own seed

Let one plant flower and dry the spikes on the plant, then rub out the small black seed. Basil crosses easily between varieties, so save from just one variety per garden.

Containers

Excellent in a 20 cm pot on a sunny sill or balcony. Use one plant per pot, supermarket pots hold 20 crammed seedlings and always collapse.