Coriander and rocket are both leaves I use constantly, and in great quantity, in the kitchen, therefore I need to keep a continual supply happening in my garden all year. This is not without its challenges, but over the years I have developed some strategies that ensure I have both these delicious herbs available for use all the time.
Plant by seed and in situ (where they are to grow). Never buy or produce seedlings of these herbs and then try to transplant them, as the stress caused by transplanting sends them straight into flower (called bolting). Both are easy to germinate, just prepare your soil, scatter seed over prepared ground, cover with seed raising mix and keep moist. If you want a more in-depth guide to starting plants from seed, check out the guide on my website.
Rocket seed, although fine, can be planted quite thickly and then cut as baby leaf after three to four weeks, coriander is better planted at 10cm intervals and needs about five to six weeks before you start to harvest the outside leaves and up to eight weeks if you want to harvest and use the whole plant and the roots. Also let some plants go to flower and self-seed around your garden.
Successive planting. This is something I’ve spoken about before on this blog. Firstly both are short lived plants and will go to flower after about two months regardless of how you try and prolong their growth; Coriander will take a bit longer in the winter but can bolt very quickly in the summer. So successive planting every two weeks is essential. To ensure a continual supply you will need to be a bit obsessive about planting these seeds regularly. I try and get into the habit of sowing some seeds every week. A bit of Coriander one week rocket the next.
Keep moist. Water stress is one of the main reasons for bolting so keep your young plants well watered. If the area you are planting them in has a tendency to dry out, increase its moisture holding capacity in the long term by adding well composted organic matter to increase the humus content of the soil and for a short term solution apply a soil wetting agent.
Fertilise for leaf growth. For both these plants we are looking for leaf growth. So you need to keep them actively growing. To do this prepare the soil they are to be planted in with a fertiliser with a high nitrogen ratio, such as pelletised poultry fertiliser. Once germinated and they have about four true leaves, feed them twice a week with a half strength high nitrogen liquid fertiliser such as Powerfeed or a fertiliser tea made from material such as poultry manure, green leafy weeds or chopped up legumes.
Keep cool. Although both rocket and coriander love full sun they will bolt in hot weather, so in summer try planting them in a slightly shaded spot that avoids hot afternoon sun or plant in between larger plants such as corm that will shade them. If this is not possible try planting them in pots that can be moved into a cooler spot if hot weather is predicted. Often in the hottest part of the summer I will sow each plant into a 20 cm pot every two weeks so I can keep then in a cooler spot.
So however you use these herbs, following these few easy tips should see you with a continual supply all year round.
Good Luck and Happy Gardening,