As with growing most plants from seed, hedge your bets. You’re not expecting every single seed to produce a whopping great basil plant, so expect to lose some along the way. But if you sow enough seeds, you improve your odds of ending up with at least a couple of plants.
It’s important to start with a good quality compost. You want a nutrient rich soil with good drainage.
Sow the seeds in April. Sprinkle the seeds onto moist potting compost in a small pot, about 2-3 inches (5cm) wide. Aim for about 5 seeds per pot so they don’t get crowded. Then cover the seeds with a thin layer of compost and leave in a warm place. The seeds should sprout in a couple of weeks.
While the seeds are sprouting, keep them warm and in sunlight. Place the pot in a saucer of water to keep the soil damp. When the small plants are established, take out the smallest two so that you have your three healthiest plants in each pot.
The plants are ready to repot again when they have their ‘true’ leaves. Seedlings grow with two small leaves opposite each other, like mini propellers. The true leaves are the ones that develop after this. Wait until the new plants have about 5 true leaves, and they’re a few inches tall, and they’re ready to be potted into their own pot.
Make sure you have a suitable container like a herb planter or window box as these plants need good drainage. The pH of the soil should be slightly acidic to neutral, at least 6.0 and below 7.5. Checking the pH every 4-6 weeks and maintaining the pH with an organic fertiliser will keep it at this level. You probably only need to use this fertiliser at about half the recommended strength to do this. Normally basil isn’t too fussy regarding soil composition but they need a bit more attention when growing indoors. Water the plant regularly and keep the soil moist, but make sure the excess water drains away underneath the pot. Don’t leave plants sat in water or they could rot. If you really want to pamper your plant, use tepid water rather than cold.
To pot plants, gently remove each seedling. Hold the plant by the stem only, and NEVER touch the roots. They are fragile, and often a bit spindly at this stage. Place the seedling in the new pot, in hole deep enough to allow the roots to spread. Tip in compost around the seedling and gently pat the soil down around the plant. Water it in well. If you are putting more than one seedling into a large pot or a winow box, try to allow about 4 inches (10cm) between plants to give them room to grow.
Harvesting the basil
Wait until the plant is about 4-5 inches (10 cm) tall before harvesting any leaves. Then just pinch or cut the leaves off as required. Try to restrict yourself to only taking the leaves, not a whole stem, as this can weaken the plant. Pinch off the tops of the plant regularly to encourage more young leaves to grow.
Basil seeds are cheap as chips. You have nothing to lose and a lot of basil to gain!