Frost has hit New Hampshire, and it’s time to clean up your raised beds if you grew summer vegetables like tomatoes and cucumbers. Emma Erler, lead horticulturist at Squam Lakes Natural Science Center, recommends starting with a thorough cleanup.
Remove diseased plants and garden debris
“If you had any sort of leaf spot on your tomato plants or any sort of fungal or bacterial disease on the plants in your garden this year, you are going to want to get rid of those entirely,” Erler says. Include the roots when you pull them out.
She recommends bagging diseased plants and disposing of them, rather than putting them in the compost pile where pathogens could survive and cause problems the following season.
Gardeners should also remove squash vines if they experienced squash vine borer infestations, since the insect can persist in the area where it lived the previous year.
Replenish the soil
Raised beds typically receive intensive use, which can deplete nutrients and cause soil levels to settle over time. Fortunately, replacing all the soil each year usually isn't necessary.
Instead, Erler recommends adding a couple of inches of finished compost that is relatively free of weeds, and incorporating it into the soil. If you do this in the fall, it gives the bed a nutrient boost before spring planting.
Erler always recommends a soil test. Testing can help you determine whether to adjust soil pH or add specific nutrients to support healthy plant growth. You can get a soil test through the UNH Extension Soil Testing Service.
Consider planting a cover crop
Cover crops can help suppress weeds, add organic matter and protect soil over the winter. For raised beds, Erler suggests considering winter-kill options such as oats or crimson clover, although there may not be enough growing time left as those crops are typically planted in late summer or early fall.
Protect the soil over winter
Snow, rain and ice can compact raised-bed soil. Covering the soil with mulch can help protect it from the elements.
Erler says strawberries and garlic benefit from a protective layer of 3 to 6 inches of straw or pine needles after they go dormant to protect the crowns from extreme freeze-thaw cycles.
Plan for crop rotation
While you are cleaning out your beds, consider rotating crops next year to help reduce insect and disease problems. Although backyard gardens may not have enough space for ideal separation, Erler says rotating crops is a useful practice.
“If you grew a crop like tomatoes, potatoes or eggplant in one bed this year, ideally you would move them to another bed as far away as you possibly can for next year, to try to get away from any disease pathogens that can overwinter in the soil,” she says.
If you are dealing with persistent fungal issues on tomatoes, Erler says it may be necessary to take a break from growing tomatoes for a few years and trying something new. “Taking a break from tomatoes for a few years and going to the local farm stand instead could be helpful.”
A little fall work goes a long way
Preparing raised beds for winter means you won’t have to start from scratch next year.
Containers often benefit from fresh potting mix each year as the potting mix compacts and loses nutrients. Raised beds generally only need organic matter added to replenish them.
With a few fall tasks, you can put your garden beds to rest and look forward to early spring planting.
Homegrown NH is a collaboration between NHPR and Squam Lakes Natural Science Center.
