Spinach is a cool weather plant. It will not grow well when the long hot days of summer start. The best way to grow your spinach is as an early season green during the spring…and then again during the cooler and shorter days of fall. If you leave your spinach in when the long, hot days of summer begin, your spinach plants will “bolt” in what seems like the blink of an eye.
But what is bolting? And how do you know when your spinach has bolted?
Bolting is when a plant gets ready to produce its seeds (or, as we say, “goes to seed”). When the plant is under stress from too little water, too much light, or too much heat it embarks on the final stage of its life. And bolting is part of this end-of-life process.
You can tell this is happening when your spinach plants go through a period of explosive growth, accompanied by a few telltale signs.
For example, as the plants bolt, their leaves begin to change from ovals to arrowhead shapes. Also, the plants begin to grow taller, and add lots and lots more leaves – which become more and more bitter the longer the plants bolt. In the final stage of bolting, as the plants are finally ready to go to seed, they will send up small clusters of flower buds.
Don’t panic if your spinach begins to bolt – it’s just part of the natural growing cycle of spinach. However, there are a few things you can do slow down the bolting process so you can harvest a bit longer.
You can plant your spinach in a section of your garden that gets full sun during the early part of spring, and then partial shade during the heat of summer. The shade from a tree can help keep the plant just cool enough to stave off bolting for an extra few weeks.
You can give your spinach plants more water if there is going to be a heat wave for a few days and then cooler weather again. This will keep your plants from bolting during the short warm spell.
You can also plant spinach varieties that are slow to bolt like Long Standing Bloomsdale. (Long Standing Bloomsdale is in my garden this year, and the first planting has just bolted in mid-June – but the second planting is still ok for now – I expect that to change when it gets up to 100 degrees later this week, no matter how much water I give it.)
You can try planting spinach alternatives which rarely bolt, like Malabar Spinach, which despite the name, isn’t exactly spinach – in fact it looks almost nothing like a spinach plant. It will, however, work as a substitute in many dishes and salads. It grows on tall vines with red stems and thicker leaves. You can also plant New Zealand Spinach, which is also called Perennial Spinach (in temperate climates it grows as an annual). These spinach-like plants tend to have thicker, more robust leaves, and like Malabar, they rarely bolt even when it gets hot outside.
What do you do when your spinach bolts?
You have a few options.
You can pull the plant immediately at the first sign of bolting, and replant with a crop that loves the long warm days of summer like snap beans. Then, you can start new spinach plants after the dog days of August (or February if your garden is in the Southern Hemisphere).
Alternatively, you can try to slow the bolting process down by pinching off the flower buds. (This is my preferred method. Once the plant begins to bolt I don’t eat the young leaves raw in salads anymore – usually I will throw the arrow shaped leaves into a stir-fry since they are still safe to eat, but starting to taste bitter.) Eventually this becomes a losing battle, since you pinch off one flower cluster one day, and two days later three new clusters have sprung up, and all the while the leaves become more and more bitter.
A third option is to accept and embrace the bolt. Let your spinach plant flower and go to seed. If the plant was true to its description, and tasty, collect the seeds and plant them come fall.