Raised beds are a great way to get into gardening because they allow gardeners of all levels to have more control over their soil, place a plot wherever they please and keep pests at bay.
Whether you just built a raised bed or are looking to prepare an existing raised bed for the growing season, there are a few steps you need to take to ensure you will have a bountiful garden.
Before you prepare a raised garden bed
First, gather a few tools. Kate Garland, horticultural specialist at the University of Maine Cooperative Extension, recommended using watering essentials — a quality hose, watering wand and watering can — along with some hand tools and a gardening fork.
“I think a short handled garden fork and hand trowel is pretty much what you need for simple tools,” Garland said. “You don’t have to spend a lot of money on those.”
You’ll also want to check for any repairs that your raised bed might need.
“The big thing is to look out for nails and screws and other sharp portions of the bed, especially if you’re going to be gardening with little ones,” Garland said.
If you are using an old raised bed, it may be near the end of its life — for example, if the wood is rotting beyond repair. Determine whether you need to replace it before you invest materials and manual labor into preparing it for planting.
“This is a great time to do those projects,” Garland said. “You’re definitely not behind right now.”
How to fill a raised bed
The main thing gardeners need to get right about raised bed preparation is the soil. Tara Nolan, co-founder of Savvy Gardening and author of “Raised Bed Revolution,” said to make sure you use a soil with a mixture of compost and peat, as well as topsoil if it is available.
“You want to get something that’s formulated for vegetable gardening,” she said. “I would get a recommendation from your local nursery.”
Garland, on the other hand, recommended a combination of 75 percent loam — the mineral component of quality soil that is a combination of sand, silt and clay — and 25 percent compost. Loam is available for purchase at garden centers or from contractors.
“With bagged products, most of the time you’re not getting anything that has loam in it,” she said. “That can work OK, but you won’t have a stable substrate that will hold up in the long run. Always see the loam and compost before you purchase it [so] you can do a simple texture test. [If it] doesn’t hold together at all, [it’s] more on the sandy side and you might want to avoid it. ”
If you are using an already-filled raised bed, either from years past in your yard or in a community garden, you will still need to amend the soil. A soil test from the University of Maine Cooperative Extension will help you figure out what you need.
“It’s an investment of $18, but the quality of your soil is going to play a huge role in the quality of your garden,” Garland said. “About two weeks after [you mail it in], you’ll get really good information about soil, pH and what you need to add to the soil.”
Preparing a raised bed
The only hard-and-fast rule for timing raised bed prep is to wait for the soil to be dry before working it. Garland said that a good sign that soil is dry enough to work is if your trowel doesn’t have a clump of mud stuck to it when you stick it in and pull it back out.
Once your soil is dry enough, the first thing you will want to do is remove the weeds.
“Make sure you get as much of the root system as possible,” Garland said. “If you yank it and leave roots behind, you’re really not doing much other than wasting your time. Get that [gardening] fork in there, loosen the soil around the roots as much as possible so you can get a hold of the root.”
Even weeds around the raised bed need to be removed or covered with a layer of mulch to suppress them.
“Those little weeds around the base of the planters grow up and can be tall enough to get over that edge and set hundreds of weed seeds directly into the garden bed,” Garland said. “I would either try to pull them, which can be challenging, or just cut them back once a month.”
If you planted a cover crop at the end of last season that has not died back, such as winter rye, pull it up. Other cover crops, like oats, will die during the winter and can serve as mulch in the spring. Others still, like clover, can be turned into the soil and left to set for a few weeks before planting to allow beneficial nitrogen to work its way into the soil.
Next, you may have to loosen the existing soil to promote root growth. Raised beds have the benefit of not experiencing foot traffic when they lay fallow, but the soil does settle over time. It is important to disturb the soil as little as possible in order to maintain a healthy ecosystem below the surface and prevent weeds further down in the soil from coming up and germinating. Garland said to just plant a gardening fork down in the soil and wiggle it back and forth to loosen compacted layers.
Then, add compost. Even if your soil has compost mixed in already, it is recommended to add compost to your raised bed before planting. Garland and Nolan both say that adding compost to a raised bed in the fall is preferable so the compost can go through the natural freeze thaw cycles, but you can still add a 1-inch layer of compost in the spring.
If you have overwintered crops like garlic in your raised bed, just work gently around them.
“I’ll weed in between the garlic [and] if I add compost to the bed, I shake it gently around the plants that are already there,” Nolan said.
Also, Garland said that now is a good time to mulch overwintered crops with straw or bark to prevent weeds and retain moisture in the soil.
Once your bed is weed-free, loose and amended, water the bed and wait a day or so before diving into planting.
“You might find that the soil has settled a little bit and want to [add more] next day,” Garland said. “There’s nothing stopping you from planting the same day, it’s just good practice to water it and let it settle.”