What Happens When a Plant Bolts?

White cilantro flowers mixing with colorful annuals in the summer garden.

In most gardening climates there’s a transition period when the cool temperatures of spring start to give way to the warmer days of summer. For those of us who love summer, it’s a time to rejoice – our favorite season of the year has finally arrived. We revel in the heat and sun! But, for those of us who prefer cooler temperatures, we might start to get a little cranky with the arrival of hotter days.

Did you know the vegetables in our gardens have weather preferences just like us gardeners? Some vegetables grow best in the mild temperatures of the early season – lettuces, cilantro, radishes, and spinach. And others seem to sit and sulk in the garden until the thermometer starts creeping over 80 degrees F – eggplant, peppers, basil, summer squash.

You may notice that when your particular garden hits this change from spring to summer some of your cool weather vegetables start to bolt.

BOLTING VEGETABLES AND WHAT TO DO ABOUT THEM

Spinach going to seed in the early summer garden.

What is bolting?

Have you ever noticed that right around the beginning of summer your spinach crop starts to send up flowers? This is called bolting, or going to seed. It’s a natural occurrence that signals the end of the plant’s life cycle.

It’s commonly caused by increasing day length and warming soil temperatures which encourage the plant to move into its reproductive phase. It abandons leaf production and starts producing flowers and seeds so it can spread itself around and live for another generation.

Which vegetables are more likely to bolt?

Bolting occurs with early spring vegetables like arugula, spinach, radishes, salad mixes, cilantro, and broccoli.

The problem with bolting is the vegetables quickly become inedible as the plant shifts its focus and energy towards producing flowers. You might notice that the taste of the vegetable changes, becoming more bitter or losing its taste altogether.

Spinach starting to flower.

What should you do about bolting vegetables?

In the late spring it’s best to stay on top of harvesting these sensitive vegetables so you don’t get surprised by a row of bolted cilantro that you didn’t even get around to harvesting yet. If you do see early signs of bolting, harvest as much as possible before it really gets going.

With vegetables like cilantro or salad mix, you can use scissors to cut the entire row down to a few inches high. This might buy you a little extra time, but bolting is inevitable eventually.

How do you prevent vegetables from bolting?

Bolting vegetables can be frustrating. It seems like as soon as they really get going and you’re enjoying the harvests, they send up a flower. Because bolting is a result of increasing day length and temperature, there’s not much you can do to prevent bolting altogether in your garden. But, there are a few techniques you can employ throughout the season!

Arugula flowers – they’re sweet and spicy!

Work with the vegetables’ natural preferences. They grow and thrive in the cool days and cold nights of early and mid-spring. Make sure you plant all of your spring vegetables as early as possible in your garden – 4-6 weeks before your average last frost. (In Madison I plant them in mid-March in my cold frame and mid-April in the rest of my garden.)

Plant again for a fall harvest. The vegetables that grow well in spring love the fall weather even more! And the bonus about fall is that instead of increasingly warmer and longer days, it’s getting colder and darker, which makes these vegetables very happy. I find it much easier to grow cilantro, spinach, and arugula in the fall. And I have many, many more weeks of harvest than I do in spring. (Read about the best veggies to plant for fall here.)

Give them some shade. One year I visited some friends in late August and they served us fresh salad from their garden for dinner. I had to know how they still had salad in such a hot time of year in Wisconsin. I discovered they had a very shady bed in their garden that allowed them to keep growing salad greens all through the summer.

Keeping the vegetables and soil cooler with shade (either naturally, with other plants, or with shade cloth) during the height of summer will help prevent them from bolting. And planting after the summer solstice when the day length starts to decrease will also help.

Plant bolt resistant varieties. For those vegetables that often bolt in your garden, shop for seeds that say “heat tolerant” or “bolt resistant” and give those a try. Keep records so you know which ones perform the best in your climate.

A lady bug on flowering cilantro.

Let them flower. Have you ever seen a spinach flower? Did you know that arugula flowers taste spicy? It’s pretty interesting to let vegetables flower and learn what their flowers look like. They’ll also attract and feed your local pollinators. If I have the room I’ll often let them flower for awhile before ripping them out and planting a new vegetable.

Replant that space with another vegetable. Right around the time when things starting bolting in my garden is when I start to feel like I’ve run out of room. I’m usually all too happy to yank out that spinach that’s going to seed and replace it with my second planting of  green beans. Look on the bright side of bolting – you can clear out some room to plant something else! (Read about summer succession planting here.)

Embrace eating with the seasons. I eat a spinach salad from my garden for many months of the year and it’s one of my favorite vegetables to grow. But, when summer comes and all of my spinach goes to seed, I accept it.

Instead, I relish the arrival of summer and expand my definition of salad and create fresh dishes from the short-lived summer crops like summer squashes, tomatoes, cucumbers. One of the joys of gardening is eating with the seasons. Think creatively in the kitchen and focus on eating what’s coming out of your garden or the farmers’ market that week.

See, bolting isn’t so bad! It’s a natural process that has nothing to do with your skills as a gardener. It’s something that happens to all of us! Learning to understand and work with Mother Nature is the path to less frustration and more success in your garden.

 

 

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Comments

  • […] What Happens When a Plant Bolts? – Creative Vegetable Gardener Megan Cain (SG557) […]

  • Thanks for your article, on a similar note, my mother taught me that the best fertilizer for beans, tomatoes, peppers and peas is chicken and bird droppings because of the high nitrogen content in the manure encouraged flowering and led to higher crop yeild, and she said I must avoid this on root vegetables, spinach and cabbage as it encouraged early flowering…. I also understood from her that nitrogen needs to be introduced artificially to soil as soil naturally lacks this particular nutrient, however that certain plants leech nitrogen into the soil, as happens during thunder storms as well, surely if this is the case, would nitrogen not then build up in the soil during cooler months when leafy greens and root crops do best, and when itrogen levels reach certain levels these greens then bolt, to be replaced with a vegatable that leeches nitrogen from the soil such as pulses and maize… just thinking….

    • Nitrogen is difficult to measure in the soil because it’s always fluctuating. Vegetables are heavy nitrogen feeders, but if you give them too much you’ll get a lot of green growth but not much flower or fruit set. It’s definitely a fine line!

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