On most plants, whether it’s ornamentals or edibles, the appearance of flowers is a reason to cheer. That is not the case, however, when certain herbs and vegetables send up flower stalks and go to seed. This process, called bolting, greatly affects their taste and makes your precious garden crops inedible. Find out from an expert in the field why bolting happens in plants, what you can do to prevent it, and which types of herbs and vegetables may bolt. Meet the Expert Benjamin Phillips is a vegetable crops educator at Southwest Michigan Research and Extension Center of Michigan State University. What Is Bolting? Bolting is a reaction of cool-season crops to warmer temperatures and longer days, when a rapid shift in a plant’s hormones triggers flowering. “These plants start to produce the hormones for flowering after their chilling threshold—a certain number of hours at cool temperatures—has been reached,” says Benjamin Phillips, vegetable crops educator at Michigan State University. Bolting occurs once the period of cold exposure, called vernalization, is complete. “Warm and hot days accelerate the plants’ flower development,” Phillips explains. Want more gardening tips? Sign up for our free gardening newsletter for our best growing tips, troubleshooting hacks, and more! Difference Between Bolting and Regular Blooming “For vegetables that don’t produce harvestable fruit, bolting is usually undesirable,” says Phillips. It is a premature flowering and seed production that cuts short the usability of the crops for consumption because the taste of the leaves turns bitter, and their growth is stunted. Regular blooming, on the other hand, is a desirable part of a plant’s lifecycle. Plants such as tomatoes produce flowers that are then pollinated and become fruit. How to Keep a Plant From Bolting To prevent plants from bolting, Phillips has a few suggestions. All of them require acting early, long before the plants are in your garden and about to bolt. Store Seeds in the Freezer The stage at which crops are receptive to cold exposure varies; for some of the crops, the receptiveness starts when they are seeds. “The bottom threshold for accumulating chill hours is 32°F," says Phillips. He recommends storing seeds like seed at below freezing temperatures. “When you plant them, they will start accumulating vernalization points, but storing the seeds at freezing point will give you more time before the potential bolting process of the plants could start if the conditions are present," he says. Don’t Plant Too Early Seeding or transplanting too early in the spring can give plants enough time to reach their vernalization points. But the caveat is that they will then go straight to flowering instead of making lots of leaves or roots, Phillips explains. Select Suitable Varieties Choosing an appropriate variety for your planting season and location is equally important. “Broccoli and cauliflower are flower buds, and we want these to go through a cold period,” Phillips says. A variety adapted to your area or planting season will usually vernalize just fine, however, rare open-pollinated varieties from exotic places are less likely to succeed. “You may find that a particular heirloom Romanesco cauliflower isn’t receptive to the temperatures in a typical spring in your area and will grow all summer into a massive pile of leaves without producing a head," Phillips says. You can also look for varieties that are labeled as bolt-resistant such as 'Slo-Bolt' cilantro and 'Bloomsdale' spinach. What to Do If Plants Already Bolted If you have been unsuccessful in preventing or delaying the bolting, there are a few things you do. At the first sign of bolting, if the plant is starting to shoot up but has not developed flower heads yet, harvest as many of the leaves as possible. If it is still early, the flavor might not yet be affected, and they might still be good to eat. Don’t wait, as the quality declines quickly, and a day or two can make all the difference. If the plant is an open-pollinated heirloom variety, let the plant go to seed and collect the mature, dried seeds for your garden next year. This only makes sense for heirloom seeds, not for hybrid seeds (identified as F1 in seed catalogs), because these plants are created through controlled crossbreeding, and the seeds from those plants don't produce plants that are true to the parent. Let the plant bloom—the nectar and pollen attract pollinators which improve the pollination of other garden crops such as summer squash that heavily rely on pollinators for a good crop. As a last resort, pull the plant. Plants You Should Always Keep From Bolting This is a list of crops that can potentially bolt depending on when they were planted and how long they were exposed to their required cold temperatures. Spells of warm weather during the cold period and other factors also play a role in the likelihood of bolting.1 Not all crops on this list are equally prone to bolting. The most notorious crops to bolt include cilantro, lettuce, and spinach. Cilantro Lettuce Radicchio Beets Swiss chard Spinach Basil Bok choy Broccoli Brussels sprouts Cabbage Cauliflower Collard greens Kale Kohlrabi Mizuna greens Radish Rutabaga Turnip Carrots Celery Parsley Parsnip Members of the allium family (bulb-forming onions, shallots, leeks, garlic)

Companion planting herbs allows plants to deter pests, enhance pollination, and improve soil health, Daniel Powers, founder of The Botanical Institute, says. It also leads to a lusher and a more aromatic garden all season long, “As long as you pay attention to plant families, the size of your chosen herbs, their heat tolerance and sun requirements, and if they are annual or perennial, you can mix and match according to your preferred flavors, garden space and climate,” Tanja Eskildsen, an adaptation gardener and owner of the seed shop, Perennial Vegetables, says. To find out what herbs can be planted together, read on to learn about 14 possible herb combinations. Meet the Expert Daniel Powers is the founder of The Botanical Institute. Tanja Eskildsen is an adaptation gardener and owner of the seed shop, Perennial Vegetables, Herbs That Can Be Planted Together Chives and Parsley Some herbs when grown together can boost each other’s flavor. Planting chives near parsley, for example, can improve parsley’s overall taste, as chives offer a more pungent tang to parsley. Powers explains how chives also help repel aphids and beetles which will benefit delicate parsley plants. Want more gardening tips? Sign up for our free gardening newsletter for our best-growing tips, troubleshooting hacks, and more! Lavender and Rosemary Lavender and rosemary offer splendid blooms and love the same growing conditions: full sun and well-drained soil. So, growing these plants together is ideal because you won't need to worry about having to complete two different growing methods. Meanwhile, the pretty flowers usher in a pop of color to your garden. Basil and Oregano According to Powers, both plants can keep away pests. Basil can help repel mosquitoes, spider mites, and aphids. While oregano also has a strong scent that keeps pests away. “Both plants enjoy similar growing conditions too,” Powers says. Chives and Rosemary Sometimes herbs should be planted together because they have different root depths. This includes chives and rosemary, Powers says. By having differing root depths, both plants won't need to compete for resources like water. Sage and Thyme Thyme is a good companion plant with almost all herbs, but especially sage because both prefer less water. Thyme likes fast-draining soil whereas sage prefers drought-like conditions. Lavender and Sage Both plants prefer dry and sunny growing conditions, which is perfect because not many herbs thrive in hot climates and handle less water, Eskildsen explains. At the same time, lavender can also help repel animals such as deer and rabbits that like to nibble on sage, making these two plants even better for each other. Marjoram and Basil Occasionally, one plant might support the other more. Marjoram, for example, can improve the flavor and growth of basil, Powers says. Marjoram is a herb with a sweet citrus smell and taste, so growing it next to basil can make basil taste a bit sweeter. However, both herbs can create a more aromatic environment in a common vegetable garden, discouraging pests in the process. Thus, either plant can make a great addition to the garden. Cilantro and Dill Cilantro and dill can both attract beneficial insects like pollinators and predatory insects that control pest populations for each other, Powers says. For example, hoverflies are drawn to cilantro, and their larvae eat aphids, a common antagonist in any healthy garden. Parsley and Chervil Parsley, a flowering herb, and chervil, a member of the parsley family, are good garden companions because they like similar growing conditions. “Parsley can help enhance chervil’s growth and flavor, as they enjoy similar light and water conditions,” Powers says. Thyme and Rosemary Thyme and rosemary, both Mediterranean plants, thrive in dry, well-drained soil. Being planted together can help create a microclimate that suits their needs, Powers says. Not to mention, thyme repels cabbage worms and other pests of common garden plants. Dill and Chives Chives, like onions, have a pungent smell and taste, which repels pests like aphids, a common garden bug. Meanwhile, dill’s yellow flowers will draw in pollinators like butterflies and bees to your garden. Together, these herbs make a great team repelling and attracting different insects to your garden. Tarragon and Oregano Tarragon and oregano are both herbs with dainty flowers that offer lots of aroma. While both are indeed aesthetically pleasing, these two plants also prefer the same sun exposure and soil conditions, making them great companion plants in the garden. “These two plants can also benefit from each other’s presence by repelling a variety of pests due to their strong scents,” Powers says. Garlic and Rosemary Rosemary strengthens garlic’s flavor. Not to mention, both herbs also have a strong scent that deters many garden pests. These herbs also require the same soil conditions, so there's no need to maintain the plants in different flower beds. Since garlic loves sunshine and less water, rosemary makes for a great companion plant because it can quickly adapt and thrive. Marjoram and Chives Approximating the smell and appearance of green onions, chives have smaller flowers and leaves. This means they need less space in the garden while their strong odor repels many pests from the rest of your garden plants. Meanwhile, the citrus flavor of marjoram subtly sweetens the chives’ flavor. What Herbs Shouldn’t Be Planted Together Mint and most garden plants: According to Powers, mint can be incredibly invasive and can quickly overtake neighboring plants, robbing them of space, nutrients, and water. If you choose to grow mint, keep it in a separate container. Fennel and most herbs: Fennel is unfriendly to most other plants because it secretes a substance that can inhibit the growth of other plants around it, Powers says. It’s best to plant this herb away from others. Cilantro and Tarragon: These herbs prefer different growing conditions. For example, cilantro likes cooler temperatures and can flower quickly in warmer weather, while tarragon thrives in warm, dry conditions, Powers says. Planting these herbs together can make it difficult to keep each herb happy. Basil and Sage: These plants prefer different soil conditions. Basil loves moist soil and more frequent watering, while sage prefers well-drained, drier soil. Powers explains. Growing these together makes it so neither receives its optimal growing conditions. Peppermint and Parsley: Peppermint, like mint, tends to take over with a sprawling root system. This is why peppermint can overwhelm parsley, a single-root plant. Lemon balm and most garden plants: According to Eskildsen, lemon balm is an aggressive grower and will dominate a space. Additional Tips for a Thriving Herb Garden Know the Final Size of Your Herbs Some herbs grow into tall bushes and others stay low to the ground, Eskildsen says. Eskildsen recommends planting your tallest herbs in the background and the smaller ones in front or around it. This will help make sure each plant has enough light and make harvesting a lot easier. Identify If It's an Annual or Perennial “Some herbs you only need to plant once and others you plant every season,” Eskildsen says. To help organize your herb garden, it’s good to know if your herbs will grow in the same spot for many years or only one season, meaning it will have to be switched out for another herb eventually. Mix Shade and Sun-Loving Plants Appropriately Eskildsen explains how sun-loving and shade-tolerant plants grow well together as long as you plant the shade-tolerant plants under a taller sun-loving plant. “The foliage of the taller herb will gently shade the herb underneath allowing you maximum use of garden space," Eskildsen says.

Growing perennial herbs is a savvy way to save money in the garden and make gardening chores a lot easier. However, keeping track of the herbs that are actually perennials can be a bit of a challenge since many perennial herb plants are commonly treated like annuals in cold climates. To help you out, we’ve compiled a list of popular perennial herbs below, including a selection of the most cold hardy plants that can survive winters in the chilliest gardens. What Are Perennial Herbs? Perennial herbs are relatively long-lived plants that take more than 2 years to complete their life cycle. These plants are winter hardy in their native habitat and often get quite large as they mature. Many of our most popular culinary herbs are technically perennials, including most mints and woody-stemmed herbs like lavender. Want more gardening tips? Sign up for our free gardening newsletter for our best growing tips, troubleshooting hacks, and more! What Are Annual Herbs? Herbs that are true annuals often have tender stems and a fast growth rate and they complete their entire life cycle in less than a year. That means that if you plant annual herb seeds in spring, you can expect your plants to reach their mature size, flower, and produce seeds all before they die back in fall. Dill, cilantro, and other herbs in the carrot family fall into this category; however, many perennial herbs are treated like annuals when they’re planted outside of their hardiness zone. Perennial vs. Tender Perennial Herbs Although tender perennial herbs are technically perennial plants, tender herbs are sensitive to the cold and they don’t survive winters in chilly climates. Most growers cultivate tender perennial herbs, like basil, as annuals and allow their plants to die back in fall. However, cold-sensitive herbs can be kept alive for years by overwintering them indoors or in a heated greenhouse. If you want to grow perennial herbs with minimal effort and don’t want to bother with overwintering plants indoors, select herbs that are winter hardy in your growing zone. Many cold tolerant, perennial herbs can be cultivated outdoors year round without winter protection—and some can even be harvested when they’re covered in snow. Common Perennial Herbs From apple mint to winter savory, there are many perennial herbs to choose from. But just because herbs are perennials, doesn’t mean they’ll necessarily grow perennially in your area. Before planting any of the following herbs in your garden, doublecheck their hardiness zone to make sure they can survive winters in your garden. Anise Hyssop Apple Mint Bay Laurel Bee Balm Bronze Fennel Catnip Chives Chocolate Mint French Tarragon Garlic Chives Lavender Lemon Balm Lemon Thyme Lemon Verbena Lovage Marjoram Mountain Mint Oregano Peppermint Pineapple Sage Roman Chamomile Rosemary Sage Salad Burnet Shiso Spearmint Stevia Sweet Cicely Thyme Winter Savory 11 Perennial Herbs to Grow Many growers dream of having a large herb garden brimming with fresh herbs for cooking, tea making, and more. But if you don’t have a lot of room for growing herbs, reserve the space you do have for the herbs you use the most in your recipes and plants that are well-suited to your growing zone. If you’re having a hard time choosing between herb plants, here’s a list of 11 perennial herbs that are especially versatile in the kitchen and easy to care for. Bay Laurel If you use a lot of bay leaves in your cooking, why not grow a bay laurel tree (Laurus nobilis) or two and harvest your own bay leaves for recipes? Although bay laurels only grow perennially in USDA zones 8 through 10, these plants thrive in roomy pots and can be cultivated indoors in cold locations. Among their many charms, bay laurel plants are relatively pest-proof, they’re long-lived, and their glossy green leaves have lots of aesthetic appeal. Chives Chives grow well in gardens or pots, and they can be used—fresh or dry—to flavor salads, soups, baked potatoes, casseroles, and many more dishes. Incredibly cold tolerant, chives grow perennially in zones 3 and up and they’re fantastic companion plants for attracting bees and other pollinators to veggie gardens. If you’re tired of classic chives, try growing garlic chives instead and use the garlic-flavored leaves in any recipe that calls for garlic cloves. Lavender Many growers cultivate lavender plants just for their richly scented leaves and charming, purple flowers. However, English lavender is edible and it can be used in desserts, brewed into teas, or infused into creative cocktails and mocktails. Like many other woody-stemmed herbs, lavender grows best in full sun and well-draining soil, and most varieties are winter hardy from zones 5 through 9. Marjoram There are several types of marjoram, but the most common variety for cooking is only hardy from zones 9 and up. If you live in a warm location, you can grow marjoram outdoors year round, but growers in colder areas should move their plants inside in winter if they want to keep them around. Marjoram leaves taste a bit like citrus mixed with pine and they can be used to elevate the taste of pasta sauces and other savory treats. Mint Growers have lots of mint plants to choose from, but peppermint and spearmint are usually the easiest plants to find at garden centers. Apple mint, chocolate mint, lemon balm, and catnip also fall into the mint category and, like other mint plants, they grow best when they’re provided with regular water and plenty of sun. Most mint plants grow aggressively and they should be kept in pots or dedicated raised beds to avoid invasiveness; however, native mountain mint plants are more mild-mannered and they’re especially attractive to native bees. Oregano Another cold hardy herb, common oregano grows perennially in zones 4 and up, and plants often remain evergreen through the winter months. In fact, you may be able to harvest small quantities of oregano leaves even when there’s snow on the ground and use those leaves to flavor pizza sauces, soups, and other cozy treats. For more variety, try lesser known oregano varieties like Greek oregano, Mexican oregano, or Syrian oregano. Roman Chamomile German chamomile and Roman chamomile are both grown for herbal teas; however, only Roman chamomile grows perennially. Compared to German chamomile, Roman chamomile plants are relatively short and they sport smaller, white and yellow flowers that are highly attractive to pollinators. Picking chamomile flowers every day or two keeps plants productive, and it’s the best way to boost the size of your chamomile harvest. Sage A classic herb for flavoring roasted meats and veggies, sage plants maintain a relatively upright growth habit and usually max out at around two to three feet tall. These plants grow well in pots or garden beds, but they should be kept in full sun and well-draining soil to avoid issues like root rot. Most culinary sage plants boast soft, silvery-green leaves, but if you love lots of garden color, you may want to grow purple or tricolor sage instead. Tarragon Hardy in zones 4 and up, tarragon is a popular ingredient in French cuisine and its licorice-flavored leaves are often blended into butter or infused into vinegar or olive oil. As with other homegrown herbs, tarragon leaves can be used fresh or they can be frozen or dried for longer term storage. Not only are tarragon plants tasty, but their buttery orange flowers bring lots of color to herb beds and flower pots—and they’re highly attractive to pollinators, too. Thyme Another woody-stemmed herb from the Mediterranean region, thyme prefers to grow in well-draining, sandy soil and full sun. While common thyme is the most popular thyme variety for culinary use, adventurous gardeners may want to grow other types of thyme instead. Lemon thyme, for instance, is prized for its lemony flavor; while creeping thyme has a particularly low growth habit and can be used as an edible ground cover or grass alternative in lawns. Winter Savory Unlike summer savory, winter savory is a perennial plant that has woody stems and a deep, rich flavor with notes of black pepper and pine. Hardy to zone 4, winter savory is often grown as a marjoram substitute in cold climates, but it’s also useful as a pest-repelling companion plant in vegetable gardens. If you want to dry woody-stemmed herbs like winter savory, gather the herb stems in bundles and hang them in a warm, dry place with good air flow until the stems are thoroughly dry and brittle.