A Pollination Moment
from Pollinator Paradise Farmer's Market E-mail reminders

6/28/2003 
Bolting

This is the last week for spinach and lettuce. Most of the spinach is bolting now, and the lettuce will be bolting by next week.  In case you are not a gardener, when a plant bolts, that means it has put up a stalk and is starting to create flowers.  Instead of producing tender large leaves, the plant's energy goes into reproduction.

I'm not sure where the term 'bolting' comes from, but the speed with which the flowering stalk comes up is suggestive of a kid bolting out the door, or a horse bolting through the gate.  My dictionary includes this definition of bolt: "To flower or produce seeds prematurely".  My spinach really is not bolting "prematurely" given the hot weather that we had last week.  It's right on time.  We call it premature because we'd like to continue to harvest the leaves.  But the plant wants to get on with its life.

Unlike lettuce, when spinach bolts it does not get bitter.  Lettuce produces bitter alkaloids when it bolts.  The alkaloids probably evolved to protect the flowers and fruits from pests.  Actually, some lettuce varieties bolt without tasting bitter, while other varieties taste bitter before bolting.  That's probably a result of selection of modern varieties.  Often reproduction and bitter alkaloids go together in lettuces.

Not so for spinach, which don't produce alkaloids.  When spinach bolts it just makes smaller leaves, and thicker stems.  The leaves become too small to bother picking, but if the older large leaves remain, they are perfectly good to eat.  If they aren't picked soon after the plant bolts, the large leaves turn yellow as the plant withdraws resources for reproduction.

And what of spinach flowers?  Spinach is in the goosefoot family, Chenopodiaceae.  This family includes garden beets and sugar beets, as well as chard.  Also the notable weed, Kochia.  Flowers in this family are small and green, in dense clusters.  They are mostly wind pollinated, so there is no need for large showy flowers to attract bees, birds, or butterflies.  Shake the plant when it is full bloom, and you will see clouds of pollen taking off in the wind.  If you let the spinach flower, take a look at the little flowers with a hand lens.  Let it go past the pollen puffing stage and seeds will form.

With spinach bolting, and lettuce soon to bolt, those of us who love greens are often out of luck in the heat of the summer.  This year I've planted New Zealand Spinach and vegetable Amaranth for the first time.  They are supposed to tolerate heat, and be good to eat.  We will have a chance to evaluate them when they are ready to harvest, by the end of July.

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June 25, 2003
Copyright © 2003, Karen Strickler. All rights reserved.