This one mistake caused my spinach to bolt – and how I learned to easily avoid this common problem in future

This is my first year growing vegetables and I've jumped right in with a range of crops. It's proven to be both a fruitful and educational process, especially when it came to my spinach plants. Unfortunately, I made one mistake that led to my spinach bolting. But, I now know it's easily avoidable for next time.

When you grow spinach, it's important to be aware of a few things: the amount of space it needs, how much water it requires, and, where I went wrong, where to position it for optimal temperature. By placing my spinach plants in a too-hot environment, I encouraged them to send up flower spikes early. This is known as bolting. And although spinach flowers are beautiful in their own right, once they appear, your spinach won't return to producing its tasty leaves.

The same applies when growing spinach in pots; you need to get all the growing requirements right for your plant to produce a bumper harvest. To help you avoid the same mistake I did, I explore why temperature is a critical factor in growing spinach, alongside insights from a gardening expert on other causes of spinach bolting.

What caused my spinach to bolt?

I started growing spinach in my greenhouse in early spring when outdoor temperatures were still too chilly to directly sow spinach seeds (see the full range at Burpee) outdoors. It would have been a seed sowing mistake to grow spinach outdoors when there was still a risk of late frost.

My greenhouse provided a controlled environment to provide sufficient warmth for my spinach seeds to germinate and to support early growth.

Where I went wrong, however, was leaving them in my greenhouse for too long. I grew spinach in pots, so it was easy enough to leave them on my greenhouse shelf, rather than transplanting seedlings into the ground in my garden.

The result? My spinach plants were sweltering in my greenhouse as the spring temperatures warmed up.

'Spinach likes cooler temps and shorter days. So, if it gets too hot or too much sun, that can cause it to bolt,' explains Lindsey Chastain, homesteader and founder at The Waddle and Cluck. 'If you plant spinach in the fall or early spring after the last frost, you are much less likely to get bolting,' she explains.

Although I did sow my spinach seeds in early spring, keeping the plants in the greenhouse once temperatures warmed up created an environment more reminiscent of summer – far too warm for spinach, which prefers temperatures between 60–70°F.

This hotter environment tricked my plants into flowering and going to seed prematurely, before I was able to harvest my spinach.

To avoid spinach bolting, I should have moved my spinach plants out of the greenhouse once the risk of frost had passed, or waited to sow seeds outdoors when the risk frost had passed. The outdoor spring temperatures would have then provided me with a harvest ahead of the hotter months settling in.

Lindsey Chastain

Lindsey Chastain, a dedicated homesteader and skilled writer, is the driving force behind The Waddle and Cluck, a platform that celebrates sustainable living, gardening, and responsible farming

Other causes of spinach bolting

Temperature isn't the only cause behind spinach bolting. There are a few vegetable growing mistakes that can lead to those flower spikes emerging.

'The other thing that can cause bolting is stress,' says Lindsey. 'The best way to avoid stress is to give the spinach proper care. Don't overwater, don't overcrowd, and give the plant healthy soil,' she adds.

Aim to provide at least three inches of space between each spinach plant, and if you're growing it in pots, opt for a container that is at least 12 inches deep. These grow bags from Amazon will also work well.

Likewise, spinach plants require consistent moisture to stay hydrated. This is where a prolonged position in a greenhouse also contributes to bolting, where the higher temperatures dry out the soil more quickly.

You can use this soil moisture meter from Amazon to check when the couple top inches have dried out, indicating it's ready for a top up of water.

Giving your spinach a boost of essential plant nutrients (with this leafy green fertilizer from Amazon) will also help enrich your spinach's soil to encourage a greater harvest.

FAQs

Are spinach flowers edible?

Spinach flowers are edible, but at this point in your spinach plant's lifecycle, the crop becomes very bitter and tough. This can make them better for cooking, rather than eating fresh in salads.

How can I extend a spinach harvest?

By harvesting the outer leaves of spinach, you can encourage continuous growth and an extended harvest before the plant goes to seed. You can also mulch your spinach plant to keep the soil cool, as higher temperatures will encourage the plant to bolt and flower.

Although I made this mistake when growing spinach in spring, I now have another opportunity to grow spinach, as it lands on the list of vegetables to plant in September. After the hottest days of summer, fall provides cooler temperatures for spinach to grow directly in the garden. It's fast-growing, so you can get a harvest within just 30 days, ahead of the first frost.

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