Q How do I avoid rocket bolting (flowering)?
A The peppery leaves of rocket become tougher and less palatable as the plant moves towards flowering. It tends to bolt (flower) when cold nights follow hot days, or in other conditions that stress the plant.
Keeping the young plants moist, reducing the soil temperature and keeping the plants damp are three ways that people suggest you can try to avoid bolting. To achieve this, Which? Gardening magazine tried mulching the young plants of seed sown in mid-May to retain moisture, but were disappointed to see that they bolted at the same time as our unmulched control, without producing a crop of harvestable leaves.
Sowing the seed in modules so that we could ensure that the young plants remained well watered was a failure, too, as they never formed plants that were large enough to be worth planting out.
Sowing after the longest day, to avoid the shock of warm days and cold nights was more successful. We harvested one crop of leaves from plants sown at the end of June, and two from plants sown at the start of August. Again, we found that mulching the plants had no effect on how quickly they bolted, even when sown in August.
WHICH? GARDENING RECOMMENDATION
Treat plants as a ‘cut-and-come-again’ crop, making a sowing every two weeks to keep a steady supply of leaves coming.