Bolting is often looked at as a bad thing. We've left a plant too long and it is beyond harvest...MORE quality. The natural inclination is to rip it out and plant something else in its place. If you can resist that temptation long enough to let the seeds ripen and fall, the plant will succession plant for you.
Sometimes the weather dictates when plants go to seed. If temperatures soar before early spring crops have had much time to grow, cool weather lovers, like spinach and corn salad, will throw in the towel and send up seed stalks. Likewise, if biennials, like broccoli and kale, experience a sudden dip in temperatures, they will think they've gone through winter and are entering their second growing season and go to seed. So we might not be able to control which plants self sow when, but it is in their nature to seed and it will happen eventually.
Controlling Self-Sowing VegetablesWith vegetables grown for their leaves, like lettuce, kale, and herbs, you might want to speed things up and encourage them to self seed, by not harvesting their leaves. Harvesting encourages new leaf growth. When plants are left to their own devices, they will go to seed as soon as possible.
In warmer climates, with two growing seasons, you may even get volunteers of beans, squash and tomatoes. However it is not recommended you leave plant debris in the garden over winter, because the risk of over-wintering diseases and pests outweighs the rewards of free food. Better to save the seed to plant fresh next year.
If you'd rather your vegetable plants seed in another space in the garden, wait until the seeds have dried and are just about ready to drop. Then cut of the entire seed head and toss or scatter the seed elsewhere.
Self-sown plants are not very good at spacing them selves optimally and some thinning will probably be required. Thinning is a tedious tasks, but it's made a bit more palatable if you remember that most of the thinned plants are edible and can be added to salads, soups, or vegetable dishes. More free food!
You may also get some volunteers in the compost bin. Wherever they sprout, keep in mind that only open pollinated (OP) varieties will grow true to seed and even they may surprise you, if you've planted more than one variety and they've cross pollinated. Of course, surprises can be good, too. You may stumble on a new hybrid that you really like. Then you'll have the fun of trying to recreate the cross that lead to it.
A bonus of allowing some plants to flower and go to seed is that many of the flowers attract beneficial insects. The clustered flowers of plants with umbels, like dill, fennel, and carrots, are great for attracting parasitic wasps, which feed on peskier insects. They are also attractive to pollinators and butterflies.
Bottom line is, if you can learn to allow some randomness and serendipity in your garden, it just might delight you.
Some spring bolting plants that will self-sow for summer or fall include:
Arugula Arugula is one of the earliest vegetables to start growing in spring. It will try to go to seed quickly, as soon as the temperatures start to warm. New plants won't last long in the hot sun, but you can keep them going longer by planting taller plants nearby, to shade them.
Asian Greens We grow and eat a lot of Asian greens, like bok choy and mizuna. Many will continue growing if you use them as cut-and-come-again crops. But they will eventually go to seed. Let them. You could have new plants all season.
Borage always self-sows. You will not only have new plants this season, tiny seedlings will pop up early next season. Since it is the flowers we harvest and use, you will need to ease up on harvesting, if you want this perpetual sowing, but there are usually plenty of flowers to go around.
Broccoli raab is actually more closely related to turnips, than broccoli. It is the leaves and stems we cook and eat. This is an extremely early to sprout vegetable and it won't take much heat for it to bolt to flower and seed. The older plants will get tough, but the new seedlings will be tender. Don't give up hope, the seeds might not sprout until the temperatures cool down in the fall.Carrots can have a long growing season, so not everyone will have enough time to see their self-sowers mature. But if you choose faster maturing varieties, like the small, round varieties, you will stand a better chance. A bonus of letting carrots go to seed is the beneficial insects their flowers attract.
Cilantro is another leafy edible that prefers growing in cool weather. If you get your plants out very early in the spring, you may have some bolting and re-seeding before the summer heat sets in. More likely you will start to see volunteers popping up as fall arrives.
Collards Collard greens are very popular in the Southern U.S., but they can be grown just about anywhere. And like most cole crops, they like to go to seed. Collards can be large plants and you may not have the room to let one idle until it drops its seeds, but if you do, go for it.
Corn Salade (Mache) Corn salad is so cold hardy, you can winter sow it. However, like arugula, it tends to go to seed as soon as the first warms spring days arrive. You may not get new plants the same spring, but keep an eye out. They could come back in the fall or even next year.
Dill Dill is a prodigious self-sower. You may find new dill plants coming up all over your garden. Although it is tempting to harvest every last seed, let a few fend for themselves. The more plants you have, the more you have to harvest.
Fennel You will have better luck with the leafy fennel herb re-seeding, than the bulbing variety. Like carrots and dill, fennel has flowers that beneficial insects adore. And as with dill, although you may want to harvest every last fennel seed, let a few escape to re-seed and provide you with new, fresh plants.
Lettuce Lettuce will continue growing throughout the summer, if you give it plenty of water and harvest it as cut-and-come-again. However, sooner or later a plant or two or three will manage to bolt. Don't pull them out too quickly. Most varieties of lettuce are only too happy to self-sow.
Mustard Mustard greens are quick growers and most can handle the heat. The most prodigious self-sower is 'Giant Red Mustard'. This mild leafy green will pop up everywhere, for years to come. But some of the Asian mustards, like tatsoi and mizuna, are eager volunteers, too.
Radishes Radishes need to grow quickly, or they can get woody or unpleasantly hot. Most gardeners loose a few radishes to bolting and quickly pull them out. If you let the seeds fall, you will get volunteers, but you will need to keep them cool with plenty of water, to have the bulbs grow well. If you are growing edible podded radishes, you don't have to worry about the timing or the heat because your new plants will keep bolting and producing new pods.
Spinach Another cool season vegetable, spinach plants are one of the fastest to go to seed. If you have a long, cool spring, you could get volunteers to enjoy right away. Most years, you will have to wait until the temperatures start to cool down, in fall, to see new plants start emerging.
taken from https://www.thespruce.com/best-self-sowing-vegetables-
till next time, this is Becky Litterer, Becky's Greenhouse, Dougherty Iowa