How to Prepare Raised Beds for Winter

Fall is here, winter is coming soon, and I’m not yet ready to give up my crops to the first frost. My basil plants are still going strong, my tomato plants are winding down, and I’ve already planted a small bed of fall garlic and radishes. I even remembered to sow some cover crops in beds that will be unused for a while. 

I’ve learned that while my garden slows down in the winter, it never entirely stops. I live in a relatively mild climate with four distinct seasons. Every fall, I diligently prepare my raised beds for winter. Some I keep in production mode while allowing others to rest so they’re ready for my annual early spring frenzy. 

There are several tasks you can complete in the fall, not only to help prepare your beds for winter, but also to give them a head start on spring. Some of these tasks—like pulling weeds—keep you busy all year round, while other tasks—like preparing to grow winter vegetables—are very season-specific. Let’s take a look at some steps you can take now to proactively get your raised beds ready for winter. 

Hairy Vetch Cover Crop Seeds

Hairy vetch is a hard-working, fast-growing cover crop, adding large amounts of nitrogen into the soil, benefiting the next crop. It grows quickly and densely, smothering and helping to prevent pesky weeds.

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Remove Spent Annuals

Annuals grow for one year and then die. After the first frost, there’s no reason to keep your annuals in the ground any longer. Even before the first frost, when your annual plants turn brown and die off, or are simply no longer attractive or productive, go ahead and take them out. 

There’s nothing complicated about the process of removing spent annuals. Grab your favorite gardening gloves and snips, and prune them out. If you have any reason to suspect that your plants were diseased or infected with insects, dispose of them in a location where they can’t reinfect future plantings. If the crops were healthy and disease-free, you can safely add them to your compost pile.  

Removing spent annuals from your raised beds is a great way to tidy up at the end of the growing season. Removing dead plant materials will also help you further prepare your beds for winter. It’s also a good way to get rid of dead plant materials that can harbor overwintering pests. Remove any dead or decaying fruits and vegetables as well, such as tomatoes, peppers, or squash. If you leave these in your garden over the winter, all their seeds will sprout in the spring, and you’ll have a lot of extra weeding to do!

Prune Perennials

If your raised bed garden has perennial flowers or herbs, fall is an excellent time for pruning them back. Many flowers can be cut back to the ground or to a short stem. You don’t need to cut down everything, however. Ornamental grasses, echinacea, hyssop, milkweeds, and bee balm all offer ornamental value, foraging opportunities for winter birds, and protection for overwintering beneficial insects. 

Perennials that die back completely are clearly not adding any ornamental value to your garden. Their dead tops can be removed from the raised beds and composted or disposed of. It’s best to wait until after the first frost to cut back your perennials because these plants continue to gather energy from the sun as long as their leaves are green.

If you are growing native plants, some of these perennials will host insects over the cold seasons. Leave the stalks of these if you’d like to give solitary bees, wasps, and beetles a place to hang out.

Protect Perennials

Cutting back perennials is one task that removes the above-ground vegetation. Protecting your seasonal herbaceous perennials for the winter focuses on the below-ground roots, bulbs, and rhizomes. Protecting your woody perennials focuses on both above and below-ground parts of the plants. 

Mulch around your perennials to help protect their roots from dramatic temperature fluctuations and severe cold. Mulching around your plants also helps retain soil moisture and deters weeds from sprouting up from bare soil. You can apply mulch directly over dormant perennial roots but if your perennials are still standing, leave a little space around the main stems so you don’t suffocate your plants. 

There isn’t much you can do about the weather, but you can still extend your growing season. Want to try keeping your cool-season veggies producing a little longer or, in mild climates, throughout the entire winter? 

Cover your cool-season crops with a mini greenhouse, cold frame, or floating row cover to extend your season and keep your perennials going strong. These versatile and portable seasonal protection systems keep your plants safe during light freezes but probably won’t protect your plants enough for them to survive arctic blasts. They’ll help extend your growing season in the coldest winters, and even allow you to grow and harvest some crops until spring in mild climates. 

Grow Cool-Season Crops

Cool weather doesn’t mean the end of the garden season. To prepare for your winter garden, grow cool-season crops. You can grow collards, spinach, kale, lettuce, broccoli, and more, long after your heat-loving summer crops have died. Your herb garden may have hardy herbs like rosemary, sage, thyme, oregano, and chives that you can keep harvesting throughout the winter. 

Remove Tender Bulbs and Corms

Do you have dahlias, gladiolas, elephant ears, tuberous begonias, or caladiums that you’d like to overwinter? In warm climates, you can leave these bulbs in the ground all year. But if you’re beyond their winter tolerance, you’ll need to dig, protect, and replant these tender bulbs, tubers, and corms each year. 

When the foliage dries up at the end of the year or after the first frost, it’s time to dig these plants and prepare them for winter storage. Don’t worry about leaving them in the ground until the first frost. Usually, the first frost is light, and the ground is still relatively warm. The leafy foliage and stems will die back, but the underground bulbs will be okay. Dig them promptly, however, to protect them from a more severe frost and potential diseases from cold, perpetually moist soil. 

Pull Weeds

Why pull weeds when you aren’t actively gardening? Because the more weeds you pull now, the fewer you’ll have to pull in the spring. Any weeds that go to seed will spawn dozens, if not hundreds, of baby weeds that you can avoid entirely by pulling them now. Leaving weeds in the garden also provides hiding places for garden pests to overwinter. Also, weeds are using the same soil nutrients that your garden plants want. Why encourage the competition?

When pulling weeds, make sure you remove the entire weed. Work when the soil is moist, rather than dry or compacted, to make it easier to get the entire root. Loosen the soil around the roots if you need to and carefully remove all parts of the weed. Many weeds are incredibly persistent and will sprout up from root and stem segments left in the ground. You can, with caution, compost weeds, or throw them out if you’re concerned about reintroducing them after composting.

Plant Cover Crops

Planting cover crops in the fall boosts your garden soil quality for the following spring. Use this downtime between active gardening seasons to give your raised beds new life, and improved soil. Cover crops are often referred to as living mulch or green manure. 

These crops are fast-growing plants, usually annuals, that you use in rotation with your garden crops to help improve soil conditions. They improve soil and garden health by breaking up dense soil to improve aeration and water retention, attracting pollinators, suppressing weeds, improving nutrient availability, and reducing soil erosion. 

Winter rye, crimson clover, hairy vetch, alfalfa, barley, peas, and fava beans all make excellent fall and winter cover crops for your raised bed garden. Sow one of these cover crops across your entire raised bed and let it grow until you’re ready to use the bed again the following spring. When you’re ready for spring planting, cut down your cover crops, turn the roots into the soil, and add the tops to your compost pile and you’ll have multiple opportunities for soil enrichment!

Remove Decorations

When you clean up your yard at the end of the season, you’ll remove dead crops, weeds, and decorations, including stakes, tags, trellises, and garden gnomes. This is the perfect opportunity to clean off your decor, scrub off mildew, and remove dead plant matter that may be clinging to these items. Use your hose and a scrub brush to wash away insect eggs, slug and snail eggs, and any grime that has accumulated during the summer.  

You won’t need these items again until the next year so you can store them in a protected location to keep them clean. If you like the structure they provide, however, there’s no harm in putting them back in your garden to provide some winter interest. While you’re out there, take the opportunity to remove any plastic or metal plant tags that may be left lying in the soil. 

Fix and Maintain

Is there a loose board in your raised bed? Do some of the nuts and bolts need tightening? Are there any other maintenance tasks you’ve been putting off? Fall is the perfect time to check these tasks off your “to-do” list. When you complete your maintenance tasks during your season’s least productive time, your beds will be ready to go in top condition as soon as the weather warms again in spring.

This is also the ideal opportunity to add any new raised beds before winter! The weather is cool, the bugs are bearable, and the season is having a quiet lull in activity levels. What better time to build a new raised bed and fill it with soil? Then, you’ll have the winter to make plans and shop for seeds in preparation for spring planting.

Boost the Soil

Your beds are full of soil but the soil level has probably dropped since you first filled it. Take this opportunity to refill raised bed with fresh soil and organic matter that can break down over winter. Add your own homemade compost or worm castings for a healthy boost. Mushroom compost and aged manure also make excellent raised bed soil amendments. 

If you enjoy the entire process of gardening, including building your own ideal soil blend, read about raised bed soils and create the perfect mix for your garden. If you prefer a simpler method, most garden centers sell raised bed soil mixes, which are a blend of products that work well together in raised beds, providing nutrients, water retention, and excellent drainage.

After you remove dead plants, fix anything that needs fixing, boost your soil, and raise the soil levels, you can add a layer of winter mulch on top. Why go through all this trouble in the fall, right before your garden goes dormant for the winter? Because all the work you’re putting into your garden right now will save you time and energy in the spring when there are many more garden-related tasks to tackle.

So go ahead and do the prep work now and take your own winter break while you dream of spring planting and the first flowers and vegetables of the new season. 

Add Winter Mulch

Mulch your raised bed garden before the winter rolls around. Mulch acts as a protective layer and insulation layer. It protects the soil from wind and water erosion. It helps regulate the soil temperature to minimize the freeze-thaw cycle that above-ground gardens are particularly susceptible to. While the mulch is in place, it blocks weeds from growing so you’ll have less work to do. 

Mulch also helps nourish the soil. Use an organic mulch that will break down relatively quickly. If you have a lawn mower and fall leaves in your yard, run the mower over the leaves to break them up and spread this shredded leaf mulch on your garden beds. The leaves will act as a protective layer of mulch and they’ll break down and add their nutrients to your soil. Turn them under in the spring when you’re ready for spring planting.

Add a three or four-inch layer of biodegradable mulch. If you don’t have leaf mulch handy, hay or straw works well, as do pine needles. When you grow cover crops through the winter, these will act as a living mulch so you won’t need to cover them with any extra layers. Similarly, if you are growing cold-loving winter crops in your raised beds, you can add some mulch around them but don’t bury your living plants with mulch. They still need access to air and sunlight to grow well.