A quick note on bolting

March 18, 2011 § Leave a comment

Bolting is when a plant produces flowers prematurely. In the vegetable garden this is most commonly seen in mid to late summer with plants like lettuce and spinach. Day length and light intensity are natural triggers for flowering in plants and of course lettuce and spinach are cool weather short season (short daylength) crops.

Plants also bolt as a survival mechanism: if they think they are not going to live very long even very young plants will try to produce a flower to produce seed, even if day length is optimal.

Here is a Palla Rossa lettuce beginning to flower. This extending of the central portion of the plant is characteristic of heading lettuce:

Note the following:

Plant is very healthy so not bolting in response to ‘survival issues’;

Bright, sunny day implies mid-summer day lengths …

… we can conclude the person who planted it put it in the ground at the wrong time. I can confirm she did. I can also confirm said plant tasted like an old boot.

As soon as most of the brassica, celery, root vegetables, lettuce and most soft herbs flower proper they lose flavour and texture. Picked within a few days of the first signs of flowering they won’t taste too bad, though in some cases it might be better to leave the plant flower; appreciate its beauty, maybe use a few flowers as garnishes and/or collect seed from it.

The broccoli in the image below is a few days to a week past optimal harvest date- you can see that a few of the florets are about to open into yellow flowers.

Conversly some cultivars have an improved flavour if left to flower- purple chuy sum (a flowering brassica), kailaan chinese stem broccoli and some kales, for example.

Bolt resistant varieties take longer to develop a seed stalk and so focus on vegetative growth for longer, but there is no guarantee that bolting will not occur. Managing environmental factors (see below) will mitigate if not eliminate the likelihood of bolting in vegetable crops.

Watering regularly and shading from the sun is key to keeping cool weather crops happy if you’re growing them out of season. See companion and inter-planting for some ideas on how to create shady conditions in your garden.


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