How to Grow Basil Indoors Year-Round Without It Wilting

A little attention in the first week prevents much of the wilting.

1. Check whether the soil is dry or saturated. That tells you which direction to correct.
2. Move the plant to the brightest suitable spot (see Light below). Store displays can be dimmer than a sunny sill, or very different.
3. Check that water can drain. Holes in nursery pots can be blocked by tangled roots.
4. Hold off on fertilizer at first. A stressed plant needs to settle before it can use added nutrients.
5. If the pot is crowded with many stems, you can gently separate them into a few clumps once the plant has settled.
6. Skip heavy pruning for the first week or so, until the plant has adjusted.

Too much water and too little can look similar at a glance. A wilted plant with dry, crumbly soil is thirsty. A wilted plant with soggy, heavy soil may have roots short of air. Always check the soil before reaching for the watering can.

Low light is a third cause. Basil stretching toward a window, with pale, sparse leaves and long gaps between them, may be drooping because it is not getting enough light, not because of a water problem.

University of California guidance suggests a south-facing window with a minimum of six hours of sunlight, or fluorescent lights placed about 6 inches above the plants for 14 to 16 hours a day. An east-facing window can also work. A west-facing window may get intense afternoon sun through glass, so watch for scorched, papery patches on leaves close to the glass.

In a north-facing window or a dim corner, basil survives but rarely thrives, with thin stems and small, widely spaced leaves. A small full-spectrum grow light on a timer can fill the gap. Follow the manufacturer's guidance on distance, because fixtures differ.

Basil likes soil that is evenly moist, not constantly wet. Water thoroughly when the top of the soil feels dry, let water run out of the drainage holes, and let the pot drain before returning it to its saucer. Frequent small sips only wet the surface and encourage shallow roots.

Nursery pots often hold several seedlings in a small volume of soil, so they can dry out quickly and need checking often at first. Underwatered basil droops but usually perks up soon after a thorough watering. Overwatered basil stays limp after watering, and the soil may smell sour. Dry indoor air, for example near heating vents, speeds up drying.

Use a pot with drainage holes. If you want a decorative pot without holes, keep the basil in its nursery pot and slip it inside, and empty any water that collects.

When to Repot Basil

If roots circle the pot or push out of the drainage holes, the plant has outgrown its container. Otherwise, move it to a pot a little wider once it is established and growing steadily.

Regular light pruning helps basil stay full and upright. Pinch or cut the stem just above a pair of leaves, which encourages the plant to branch from that point instead of growing tall and leggy. A tall, single-stemmed plant is more likely to flop.

Pinch off flower buds as soon as you see them. Once basil flowers, it puts energy into seed, and leaves are often described as becoming more bitter.

Harvesting a little at a time gives you fresh leaves while encouraging branching.

• Add it fresh. Tear or slice young leaves over pasta, pizza, salads, soups or roasted vegetables just before serving. Adding it near the end preserves the aroma.
• Make a quick sauce. Fresh leaves can be blended with olive oil, garlic, nuts and a little cheese into a simple pesto-style sauce.
• Use the stems. Tender upper stems can be chopped with the leaves. Tougher stems can go into stocks and sauces.
• Harvest only what you need. Pinch stems just above a pair of leaves, the same habit as pruning.

Basil is often kept out of the fridge because it can darken in the cold. A common way to store a few cut stems is in a glass of water at room temperature, with the water changed regularly.

Winter

Daylight is shorter and weaker, so a window may not be enough. This is when a grow light helps. Growth slows too, so the soil takes longer to dry and you will water less often.

Summer

Basil often grows quickly in summer, so you may harvest more often. Pots near sunny windows dry out faster, and glass can get hot in afternoon sun, so keep the plant a few inches back if leaves scorch.

Watering on a fixed schedule instead of checking the soil, keeping the plant too far from light, letting it flower, and using a pot without drainage are the usual culprits. Fixing even one often shows improvement within a couple of weeks. If yellowing, not wilting, is your main symptom, it may have a different cause.

• University of California Agriculture and Natural Resources, basil growing guidance
• University of New Hampshire Extension, "Growing Herbs in Containers"