Basil is simultaneously one of the most rewarding and most frustrating herbs to grow. Get the conditions right and it is impossibly productive; get them slightly wrong and it collapses into a leggy, blackened disappointment. The good news is that basil is very consistent in what it wants — and once you understand those requirements, reliable basil is straightforward.
What Basil Needs
Basil is a tropical herb that wants warmth, sunshine, and consistent moisture — without sitting in waterlogged soil. The non-negotiables: at least 6 hours of direct sun per day, temperatures consistently above 15C (60F), and moist but free-draining growing medium. Below 10C (50F), basil wilts and begins to suffer chilling injury. Cold drafts from an open window will cause the same damage as an actual frost.
Starting from Seed vs Buying Plants
Starting from seed is easy and economical — sow indoors 6-8 weeks before the last frost date, or on a warm windowsill at any time of year. Supermarket basil is notoriously difficult to keep alive because it is grown in very high density with minimal root space and pumped with fertilizer. If you buy supermarket basil, pot it on immediately into a larger container with good compost and keep it very warm.
Watering
Water basil when the top 15mm of compost feels dry to the touch. Water at the base of the plant, not on the leaves. Basil wilts dramatically when it needs water but recovers quickly if watered promptly. Persistent wilting despite moist soil indicates root rot — caused by sitting in waterlogged compost or a pot without drainage. Black stems at soil level are a clear sign of rot.
Pruning for Bushiness
The single most important thing you can do for productive basil is to harvest correctly. Never pull leaves from the base — pinch out growing tips from the top, cutting or pinching just above a pair of leaves. This encourages two new shoots to form at each cut, doubling the plant density with each harvest. Remove any flower buds as soon as they appear — once basil flowers (bolts), the leaves become bitter and the plant puts all energy into seed production.
Growing Outdoors vs Indoors
Outdoors, basil thrives in a warm, sheltered spot from late spring to early autumn in temperate climates. Bring it inside before the first hint of cool autumn temperatures. Indoors, a south-facing windowsill works in summer; a grow light is more reliable in winter when days are short. Basil grown under artificial light year-round can produce continuously through winter.
FAQ
Why does my basil keep dying?
The most common causes: cold temperatures (below 10C), overwatering and root rot, or insufficient light. Supermarket basil in its original pot is almost always too crowded — pot on into a larger container immediately. If the stems are black at soil level, the plant has root rot and cannot be saved.
How often should I harvest basil?
Harvest frequently — at least weekly during the growing season. Frequent harvesting by pinching growing tips keeps the plant bushy and productive. A plant that is never harvested becomes tall and leggy, then bolts quickly.
Can I grow basil with tomatoes?
Yes, they make good companions. Plant basil at the base of tomato plants where it benefits from the warmth and shelter of the tomato canopy. The combination is practical as well as traditional.
How do I store harvested basil?
Basil does not refrigerate well — cold causes black spotting. Store at room temperature in a glass of water like cut flowers, or blend with olive oil and freeze in ice cube trays. Alternatively, dry bundles in a warm, airy space — though dried basil loses most of its fresh flavour.
Which basil varieties are best?
Sweet basil (Ocimum basilicum) is the standard culinary variety. Genovese basil has larger leaves and stronger flavour than most. Purple basil is decorative with good flavour. Thai basil has an anise-like flavour and is more heat-tolerant. Lemon basil is excellent for fish dishes and teas.
See also: Best Herbs for Small Raised Beds and Balcony Herb Garden Setup Guide.