How to grow coriander

Coriander, or cilantro as it’s known in the Americas, can be tricky, but a little know-how goes a long way towards success, writes Mat Pember.

By Mat Pember
Ceviche toasts with avocado and coriander
Coriander is among is one of the most polarising plants in the patch, eliciting equally passionate responses of both love and hatred among food-lovers and gardeners alike. When growing coriander, it can sometimes feel like you're in a tumultuous relationship. But have you ever considered whether perhaps coriander isn't the difficult one, but rather the grower might be the issue? We need to stop trying to change coriander, and instead try to understand it better, appreciate it for what it has to offer. And it has so much.
The first step in understanding coriander is knowing when to plant it. Despite some marketing attempts to promote "slow-bolting" varieties, the fact is that when you plant coriander in summer or the warmer end of spring, all varieties want to bolt to seed. Now, in the cool of early winter, is a better time to plant this herb. It will appreciate as much sunlight as you can offer, but don't be concerned by a lack of direct sun; even filtered light will assist growth. In cooler areas, however, protect the plants from frost by keeping them indoors at night.
Because we're growing coriander for its leaves - for now - nitrogen is in highest demand. Compost integrated into free-draining soil will meet the plant's needs here. In containers, always use good potting mix and ensure there's adequate drainage.
Coriander seeds are hard-coated, so soak them in water overnight before planting them to aid germination, and scatter them to a depth of about a centimetre. While close planting won't be an issue, a lack of moisture will be. This is the next part of better understanding coriander.
Water is important in maintaining a stable relationship, so keep the soil moist. We've found coriander to be perfectly suited to wicking beds which draw water up from a reservoir to maintain moisture levels in the soil. A lack of water stresses out the plants and even "slow-bolting" varieties will bolt to seed.
Once the seeds have germinated - around seven to 10 days after sowing - water every other day or as the weather demands: gently poke around in the soil to check moisture levels, and if you hit moisture at less than a knuckle deep it's fine; any deeper, you need to add water.
Around a month in, you should have a thin green blanket of coriander leaves, but picking is still a little way off; another month of growth, and you'll be making that longed-for Thai curry. When harvesting, remove the tops of the herb with scissors, leaving enough foliage on the plant to keep production rolling. Coriander won't burst into a glut stage and inundate you with produce, so if your demand is high, grow multiple plants.
The herb will continue to produce for another couple of months before it begins its decline. As an annual plant, it will only last a season - another opportunity to appreciate it while it's around.
The final step in understanding coriander is to know its phases of production. As the plant bolts to seed, flowers will develop; these add a more pungent flavour to dishes than the leaves and picking them encourage more to grow. A month later comes the penultimate phase of production: going to seed.
By now your plants may have given in to aphids, but this won't affect seed development. Let the pods dry on the plant before picking them for your spice rack. At this point, there's no point leaving the plants in the ground, so remove them to reveal the final phase of production: the roots.
Love it or hate it, coriander without doubt has much to offer.