Coriander needs to be grown in a really cool part of the garden where it will not be as prone to go to seed with the heat. “Cilantro” is a form of coriander that has been developed to tolerate more heat and to stay leafy for longer. Keep some seed for future propagation and sow frequently to ensure an even supply if it keeps going to seed. If you remove any flower stalks that appear, this will help to keep it leafy. In the Tropics & Sub-Tropics, plant in autumn and treat as an annual. The books say not to buy seedlings as the shock of transplanting them makes them bolt to seed but the slow bolting Vietnamese type grows very differently to the normal Coriander I’ve been told.
Below are the notes that were given to me in Vietnam from the Trang Nong Seed Co.
To prepare seed before planting out:
1. Take the required amount of seed and press it down on a flat surface with the palm of your hand to break it into pieces.
2. Put the seed into a muslin or equivalent cloth and soak overnight in water.
3. The next day, take it out of the water and leave to dry.
4. Put it into a polyethylene bag and tie the mouth of the bag tightly to prevent water.
5. Put it into the bottom of the refrigerator – temperature should be 15-16c.
6. After incubating for 72-80 hours, the seed will have germinated and you can sow.
7. Plant out leaving 20cm between rows.
Further to this, here are some added notes:
Sow seed where you want to grow it. Coriander will bolt to seed in the heat so sow it in autumn and don’t try to grow it over summer. It does like a bit of shade particularly in the afternoon. If you find that it’s still too hot for it, then grow it in the shade. Leafy greens should be grown fast so enrich your soil well, apply liquid fertiliser fortnightly and never let it dry out. Sow every two weeks for a constant supply and if you let a couple go to seed, it should self-sow if conditions are right. Ref: Sheryl Backhouse