Raised Beds 101

[HOMEGROWN.org]

The following 101, on gardening in raised beds, is a collective effort of the HOMEGROWN flock—this means you—and is very much a work in progress. Got a tip to add? A clarification to make? A point you’d like to ponder in public? Post a note in the comments box below, and we’ll incorporate it into the 101. Much obliged for your excellent help!

 

We’re not talking raised beds in the princess-and-the-pea sense, with fluffy mattresses stacked a mile high. We’re talking raised beds for growing—as in gardening boxes. Usually made out of wood planks, concrete blocks, bricks, or other recycled materials, a raised bed gives you lots of control over your growing patch. HOMEGROWN member Clare says she thinks of raised beds as giant plant pots, an explanation that works pretty well, we think. (Speaking of, see the Container Gardening 101 for growing in plant pots.) For lots of backyard gardeners and home growers, raised beds are key to healthy and successful gardening.

But let's back up a bit: Why would you choose to grow your tomatoes and zucchini in a raised bed rather than plant them directly in the ground? Lots of reasons, actually.

• Lots of city folk don’t have digable dirt to begin with. If you’re starting with, say, a concrete slab, a gravel patio, or a flat roof, you can't till into the ground, but you can build a raised bed right on top.

• Even if you do have dirt, it might not be something you want to grow edible veggies in. Urban dirt, in particular, can contain high amounts of lead, and dirt anywhere can be less than ideal for growing, whether that means heavy clay or an especially low pH.

• To take that point further, raised beds give you about as much control as you can have over growing outdoors. (Well, unless your neighbor’s cat sees your raised bed as a giant litter box. You’ll have to take that up with your neighbor.) Because you fill your bed with soil, you know exactly what’s in it, and you can adjust the mix as you see fit. Plus, since most raised beds are engineered so that you can reach all plants from the bed's exterior, without ever stepping foot in the box, the soil stays loose, easy to weed, and well draining. Fluffy, even. (OK, so there's one similarity to those princess beds, after all.)

Are you sold on the virtues of raised beds? Cool. We’ll walk through the process of creating and caring for them below, with all tips gleaned from the HOMEGROWN flock.

 

PREPARING A SPOT: PICKING A LOCATION, TO LINE OR NOT TO LINE

As with any planting project, you’ll want to monitor your available growing space in order to select the best spot possible for your raised bed or beds. Keep tabs on how much light your greater planting area gets at different times during the day—and keep notes. If you plan on growing tomatoes or other crops that need full sun, look for the sunniest spot. If you’re planning to grow an herb that can tolerate some shade, make note of the dappled and partially shaded areas. For more on site design, see the Garden Planning 101 and check out HOMEGROWN Life blogger Rachel’s post on how to map your site.

Once you know where you want to locate your raised bed or beds, you’ll want to prep their footprints. As with everything gardening related, there’s not so much a right way or a wrong way to do this as there are a million rights and a million wrongs, depending on whom you ask.

That said, if you’re concerned about soil contamination, you’ll want to create a barrier layer between the soil in your raised bed and the ground beneath it. HOMEGROWN member Mark recommends laying down 4 to 6 inches of stone, sometimes referred to as “dense grade,” and then a few inches of stone dust. “Tamp the stone dust so it's tight and then put your loam on top of that,” he writes. “Once you’re all planted, a little salt marsh hay will keep the weeds down and the moisture in.”

Other folks recommend layering newspaper or cardboard, but Rachel cautions that those materials will break down over time. She prefers putting down hardware cloth, which keeps the gophers and moles out, followed by weed fabric. If you don’t expect weeds to be an issue, “I'd go with nonwoven filter fabric, not weedcloth,” she writes. “That will keep the soils from coming into contact with each other but also allows for drainage.”

If you’re not sure whether or not you should be concerned about what’s in your soil, you can conduct a test. For more details, check out Rachel’s handy Soil Testing 101.

If you’re not concerned about comingling dirt, you can dig down into the ground, like HOMEGROWN member Pat, to turn up the existing soil and essentially increase the height of the raised bed (though some of that height isn’t so much “raised” as “sunken”). Or you can go the even less labor-intensive route and simply clear the area on which you’ll build your raised bed of weeds. For a longer rumination, check out this past discussion on bed lining.

 

CONSTRUCTING YOUR RAISED BED: CHOOSING MATERIALS

Remember that whole no-right-answers thing? Yep. Still goes. There are plenty of schools of thought on what material you should use when constructing raised beds—and just as many more schools on how deep those beds should be.

Let’s tackle building materials first. In true HOMEGROWN fashion, finding something to recycle—and, even better, finding something free to recycle, like Will did (see photo at right)—can be great. The only caveat here is that, in the same way that you want to be aware of the dirt health and safety underneath your bed, you'll want to keep in mind that any chemicals in the materials you use for the bed frame can leach less than desirable things into your soil. Pressure-treated wood is no bueno, and wood varnishes aren’t safe, either. (Think food-grade, people!)

If you’re heading to the lumber yard, Rachel recommends Douglas fir for its cost effectiveness—2x10s, to be exact. If money is no object, redwood and cedar are ideal. Erik likes red cedar for its aesthetic value and its natural resistance to rot. Pine is OK, too, Rebekah says, as long as it’s not treated. Not used to surveying lumber? Glean some inspiration from Mud Pies to Sticky Buns’ empowering post on going to the hardware store and getting it done!

One note on wood: Since you don’t want to seal or otherwise chemically weatherproof the wood, it will degrade over time, meaning your beds will have a finite lifespan. But if you’re anything like most HOMEGROWN folks, you learn by doing, and in five years or so, you may be antsy to build new beds, incorporating what you learned from your first attempt.

Other folks skip wood altogether. HOMEGROWN member Lynda used cinder blocks to build raised beds in the community garden she manages (see photo at right). “They work so well, I pulled out my lumber raised beds at home and [now] use the blocks,” she writes. Plus, you can plant in those holes in the blocks, “adding another 30 percent of planting area to the bed,” Lynda writes. “And the blocks are wide enough that you can sit on the edge and plant seeds or pull the few weeds that come up.” As if that’s not enough, “The blocks heat up very early in the season and retain the heat, so our harvests are coming in three to five weeks earlier than before.”

Still other folks like brick for its natural clay makeup, including HOMEGROWN member Deb, who stacks her beds two bricks high. “So far, not too many problems with weeds,” she writes. For a longer conversation, revisit this HOMEGROWN discussion on raised-bed building materials.

 

CONSTRUCTING YOUR RAISED BED: DETERMINING HEIGHT/DEPTH

The general shape of your bed or beds depends on your available space and what you plan to plant inside them, although sticking to a width of 4 feet or narrower ensures that you’ll be able to reach into the bed's center from either side. (Remember all of those benefits of uncompacted soil? No walking!) But how tall—or how deep, depending on how you look at it—should your raised bed be? You guessed it: It depends.

If you’ll be growing root vegetables, Rachel cautions against anything less than 8 inches and prefers more like 12 to 16. “Carrots, unless you are growing the short, stubby ones, must have deep soil, as do other root veggies, including beets, since root systems can go as far as 2 feet down,” she writes.

Other edibles don’t need as much depth. You can transplant tomato seedlings, for example, by stripping off the lowest leaves and laying the roots and the bottom part of the plant laterally in the bed before covering them with soil. “Practically all the vegetable crops you could grow in a raised bed will only set roots down to 6 inches or so, anyway,” with the notable exception of corn, writes HOMEGROWN member Trell. “Rule of thumb: If the plant will not blow over if planted directly in the ground, it will not blow over in a raised bed, either.” For more on the depth question, read through this past discussion.

Raised beds certainly aren’t one size fits all, but for one clear example, we like Erik’s blueprint. “Earlier this spring I installed a new 4' x 8' x 11" raised bed," he writes. “I used two courses of 2" x 6" x 8' smooth-finished red cedar lumber. I cut lap joints in the corners, which is a strong joint for this application. I reinforced the rails against bowing using 12" galvanized spikes drilled 16" OC, the heads of which serve as the basis for affixing PVC tubing to form a frame.

“I think 11 inches will satisfy all of my growing needs, and I prefer the added depth over what I might get using a single course of 2" x 8" or 2" x 10" lumber. I learned a lot building my bed and would make one minor modification were I to do it again, namely, to drill and spike the lap joints themselves.”

Those are two of Erik’s beds, pictured above right. “These two raised beds now grace a suburban front yard," he writes. "Each bed holds approximately 1 cubic yard of soil, and both were planted and growing the day they were installed.”

PLANS TO STEAL

• For a great set of instructions, check out these step-by-step plans, courtesy of HOMEGROWN member Powered by Tofu. 

• Help! We want more blueprints! Got a raised bed design you're willing to share? Post it in the comments section below, and we'll add a link. Thanks!

 

FILLING YOUR RAISED BED: SOIL MIX AND MAINTENANCE

After you’ve spent time and effort building your bed, you’ll want to fill it will an equally well-considered and well-balanced soil mix. If you’re buying soil, be sure to look for organic labeling and supplement it as you would otherwise with compost or compost tea.

As with planting directly in the ground, you can use season extenders—such as row covers, low tunnels, cold frames (no HOMEGROWN 101 yet, but Mother Earth News shares these free plans), and hoop houses (including this $30 model)—to lengthen your grow time.

Whether or not you eek extra weeks out of the growing season, for best results come spring, you will want to cover your beds once you’re done growing for the year. A blanket of organic matter will protect your precious soil from the elements during those chilly winter months.

After watching the soil in her friends’, neighbors’, and her own raised beds compact and degrade over the years, HOMEGROWN member Charlyn came up with a solution: Set a chicken coop on top of her raised bed during the winter and let the fallout soiled straw—and its blend of nitrogen and organic matter—infuse the dirt below.

“It was transformative,” Charlyn writes. “Sunflowers grew 8 feet high. No more yellow plants! Fewer slugs and pill bugs!” Even better? Soiled straw and raked leaves. “Over the winter, they slowly rotted down, adding to the organic matter.”

Below is her step-by-step plan for soil maintenance, starting in early October, when she puts her beds to, well, bed:

• Pile leaves on every bed.
• Place the chicken tractor on the first empty bed.
• Toss down straw and poop every week.
• Move the coop about every three weeks.
• Turn the bed lightly after the coop has been moved.
• Add ash from the fireplace whenever possible.
• Plant in the bed, usually under a cold frame, in the spring.
• Toss a handful of Bio-fish in with every plant.
• Mulch with straw or more leaves in the summer, after the plants are planted.

For more, check out Charlyn’s full post on raised-bed soil maintenance. And for another natural soil amendment, two words: rabbit poop.

Some HOMEGROWN members have taken simpler routes. Janine covered her beds with three inches of wood chips (see photo at right), which she salvaged from her town’s compost facility. Other folks opt for other types of mulch or even just leaf litter raked up from the yard. Read more about mulching—or growing garlic, yet another wintertime option—in the Garden Winterizing 101.

Before you know it, spring will be back again, and you’ll start the whole wonderful cycle over, from selecting seeds to starting seedlings to—well, keep reading.

WHAT TO PLANT IN YOUR BED AND HOW TO CARE FOR IT

You’ve got beds. You’ve got soil. Now, what can you grow? Here’s the fun part: Pretty much any and every veggie or herb is suitable for a raised bed, as well as many berries, flowers, and more. Hooray!

In fact, in most aspects, planting and tending veggies in a raised bed isn't that different from planting directly in the ground. As with in-ground planting, you can succession plant in raised beds. Scratch that: You should succession plant in raised beds. Also as with planting in ground, you should rotate what you plant in a given bed from year to year; that is, don't overtax your soil by planting tomatoes in the same spot for three years running. Raised beds are especially friendly to many methods of intensive gardening, from French intensive to square foot gardening.

For more on how to grow specific crops, check out HOMEGROWN 101s on growing lettuce, broccoli, peas, radishes, collards, and garlic. If you’re planning a school or community garden, don’t miss the Edible Gardens for Kids 101, featuring a list of the top five to plant with pint-size growers to get them pumped about good food.

As for watering, sure, you can do it by hand, but there are some handy tricks out there for self-watering raised beds, including homemade ollas. And if you’re feeling especially frisky, you can make like Rachel and install your own drip irrigation system. Got another idea? We can't wait to hear what you dream up next.

SPEAK UP!

Got a question about raised beds you'd like to put to your fellow HOMEGROWN sistren and brethren? Or a technique you’d like to share? Or a correction to make? Post it below and keep the conversation growing. (We’ll make sure to incorporate any key tips into the 101.) And just a quick recap of the other 101s mentioned above:

Container Gardening 101 | Garden Planning 101 | Landscape Site Design | Soil Testing 101 | Composting 101 | Compost Tea 101 | Raising Rabbits 101 | Growing Lettuce 101 | Growing Broccoli 101 | Growing Peas 101 | Growing Radishes 101 | Growing Collards 101 | Growing Garlic 101 | Edible Gardens for Kids 101 | Homemade Ollas 101 | Drip Irrigation System | Hoop Houses 101 | Even Cheaper Hoop Houses 101 | Garden Winterizing 101 | Selecting Seeds 101 | Starting Seeds 101

You can always find more things to plant, grow, make, craft, cook, and preserve in the HOMEGROWN 101 library. Happy gardening, everyone!

PHOTOS: (CHARD IN BED) CORNELIA; (BEDS ON GRAVEL) JENNIFER; (MULTIPLE BEDS) MEAGHAN; (BEDS LAID OUT) LYNDA; (EMPTY FRAMES) MUDPIESTOSTICKYBUNS; (RECYCLED BED) WILL; (CINDER BLOCKS) LYNDA; (TWO BEDS NEAR HOUSE) ERIK; (DEEP BED) STACEY; (HOOP HOUSE) MICHAEL; (COLD FRAME) LEONARD; (WOOD CHIPS) JANINE; (WATERING) CITY BLOSSOMS; (BLOOMING BEDS) LORI      

[Jennifer]

Ellen: I just reposted a picture of the plant on HOMEGROWN's Facebook page. Fingers crossed we get a helpful response!

[Ellen Peavey]

 Thanks Jennifer, going on vacation in three weeks will be gone the month of June back in July

[carol palmer]

The nutrients get depleted over the course of one or more gardening season. So it is essential to keep the soil in top condition throughout the season. Here are few simple tips on improving the raised bed garden soil. Spring is the right time to add fertilizers. Proper maintenance would relieve you of the burden of garden bed replacement. There are many measures to keep the nutrient level at its best . One is adding compost : add it in the fall(best way to end the gardening season).It is also the best way to clear your yard from fall yard waste. Even organic waste like food can be disposed in your compost. Check how to replenish your soil with organic waste http://www.redbins.ca/3-ways-get-rid-organic-waste/. Using soil amendments(vermiculate, compost....), planting a cover crop(they aerate the soil), trying lasagna gardening, preparing raised bed for winter are some other measures of maintainig healthy garden bed soil 

[ellen powell]

Sharing raised beds and last years crop French Camp,CA

[Ellen Peavey]

Your raised beds really look good, the soil must have plenty of compost. How high are the raised beds? Is this the first year and what kind of wood did you use?

[Tracey Clayton]

Would the use of worm fertiliser in this case be advisable?

[John F. Houpt II, PhD]

Tracy brings up a good point by the suggestion of adding worm fertilizer to a raised bed. This year,  I've added a raised bed garden (4'X8'X8") to my container garden. My soil mixture is 50% garden soil, 50% cow manure. I'll till this all together and then add my worm tower to assist in aerating and adding worm casings to the soil as a fertilizer.   To provide a local supply of compost - worm casings (worm poop), we are adding a small "worm farm" to the homestead.  Plus, it's a nice additional income source to offset the gardens, buy selling both the extra compost and worms to the local community. There is a LOT of information on Pinterest and the internet under "permaculture,  vermaculture, worm casings, worm tower, etc. If the work saves me 1 or 2 cuft of purchased compost, I am head of the game. Plus, I get rid of some of my garbage. 

[David Nuttle]

Tracy,  Worm waste is good fertilizer.  To increase natural fertility of grow-beds add about 10 percent bioactivated biochar to the soil mix in your grow-beds.

[Clara McClain]

Wow! That was a long read. I learned a heap, though! Thanks for the useful info. I'm guessing I'm going to have to switch from a lawn mower to a string trimmer to avoid damaging the containing material. I was reading a surprisingly useful review at some website called Electro Saw HQ and they recommend a few gas and battery trimmers you can get online.

Which of the string trimmers shown in that page would you all go for if you owned a medium-sized garden with lots of weed popping out all the time?

Thanks in advance to anyone who cares to look at those (or other) options and share their opinion!

[David Nuttle]

I forgot to mention that grow-beds may be part of an aquaponics system that facilitates the use of fish waste as an organic fertilizer.  For indoor crop production suggestions, see the "Healthy Foods Handbook," posted on the website for my charity, NPI (www.needfulprovision.org) ... see the 3rd topic on the upper left of this site.

David Nuttle said:

Tracy,  Worm waste is good fertilizer.  To increase natural fertility of grow-beds add about 10 percent bioactivated biochar to the soil mix in your grow-beds.

[Betty A Dominguez]

Great read!