The Bottom Line
Background
- In our area, food plants grow better in raised beds (with good compost) than they do in the ground (which is mostly sand).
- Compost is the key to gardening; the better your compost, the more you can grow in a fixed amount of space. Thus, a few raised beds with good compost are all that is needed to feed a family.
Pros
- Fewer bug eggs (in the compost of raised beds), as compared to planting in the ground.
- High-quality raised beds add an attractive (and valuable) addition to your property.
- Tall beds (16-18″ in height) are easier to plant, harvest, and cycle than short beds (8″-10″ in height).
- High-quality raised beds offer an unlimited life span (build ’em once, use them forever).
- There are several (hard won) tricks for accelerating the construction process.
- Raised beds with cover frames (like those shown below) can easily be reconfigured, converted to miniature greenhouses (by adding a clear plastic cover), or converted to shaded beds (by adding a sun fabric cover).
Cons
- Attractive high-quality raised beds are expensive. Pots and half-barrels are much cheaper but also less attractive.
- Tall beds (16-18″ in height) require large quantities of compost (compared to pots, half-barrels, and short beds (8″-10″ in height).
- High-quality raised beds can be difficult to install (if constructed from concrete block). Materials are heavy, the work laborious and exacting.
Cost
- About $500 for a tall high-quality (concrete block) raised bed (52sq’, if you do the work yourself).
- Payback period is about 5 years for high-quality beds.
Justification
- Raised garden beds provide food, add curb appeal, and can dramatically increase property value, especially when paired with rainwater collection, a biogas unit, an outside kitchen, and more. And beds made from concrete blocks last forever!
- The tall beds shown below were constructed to reclaim a mow strip along the property line; an area that is otherwise useless.
The raised beds along the West fence line are ready for planting and the new cover frames (for each bed) have been constructed (above). One of our best designs, the cover frames can be easily reconfigured to serve the needs of different plant types. The first frame (nearest in the photo) is equipped with six green plastic trellis screens for growing long beans. The frames are not anchored to the beds. This makes it easy to tilt the frame off the bed at the end of each growing cycle to replenish the compost and prepare the bed for the next cycle. When anchoring is needed, we used grooved concrete blocks (positioned over the bottom frame members) to hold the frames in place.
Each frame can be covered with sun cloth (above) to provide shade for the plants, or it can be wrapped in clear plastic to create a miniature greenhouse for Winter. The plastic is held in place by PVC clamps that we make ourselves.
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The raised beds (above) are covered with Bok Choi and Asian Long Beans (on trellises). Sun cloth is used to protect the baby Long Bean plants (below).
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The cover frame for Raised Bed #3 has been removed for cleaning as this bed is “cycled” (prepared) for replanting.
Our friends appreciate freshness. Many enjoy participating in the harvest, as shown above.
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The prep work comes first. The cover frame is rotated off the raised bed and cleaned (above). Then the frame is moved out of the way.
The front wall of the raised bed above is bowing out due to the settling of the soil below the bed. The rear wall of another bed (below) is even worse.
It’s best to wait until the soil is wet (after a rain) before starting this repair, for reasons that will become apparent shortly.
Start the repair by removing the cap blocks from the top of the back wall (to keep them clean). Then, dig a narrow trench in front of the back wall, Dig down to grade, but don’t go below the bottom block. I used a trenching shovel for this step (see image above).
Next, I used a weighted tarp to hold the compost in place during the repair. The goal here is to keep the compost from falling back into the trench that was just dug out. Then, remove the top row of blocks from the back wall.
Note that each block is packed with sand (above). Sand is great for retaining moisture, and the extra weight provides stability. If you perform this repair after a rain, the sand will be moist and won’t fall out of the concrete blocks if they are moved carefully. Try this: dislodge each block gently and slide it out of place by about an inch; then tilt it on it’s side and lift it out carefully and place it on the tarp (as shown above). This “surgical” technique will keep the sand from falling out of the blocks and will save lots of time,
Starting at one end of the bed, remove several of the bottom blocks, using the “surgical” technique described above.
Next, use a tamper (or another block) to compact the soil at grade. Fill any obvious low spots (with sand), Then, drop a half-inch layer of dry concrete mix (Quikcrete) into the trench. Then, replace the blocks, one at a time, being careful to level each block as you proceed. To make adjustments, place a 4×4 wood block on top of the concrete block and tap it lightly with a short-handled sledge.
In an attempt to keep things neat, I dumped a few pounds of the concrete mix into a bucket. The bucket is much easier to handle (and it has a “handle”) in the tight workspace.
The back wall is now finished (above). From start to finish, the repair took about an hour.
The repair of the front wall is faster and easier (above), mainly because there’s plenty of room to work.
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Our largest raised bed (#12) took almost a week to construct and fill with compost. It’s not easy to level the blocks and square the bed, but we have lots of practice! Tunneling under the driveway to extend a water line with a pressure nozzle only took a few hours, as we have become quite good at that task (see Tunneling for a New Soaker System 100717, below). The new pressure line to deliver rainwater to the new raised bed is shown in the middle image above.
The hard part of laying out a raised bed is squaring the corners. If they’re not square, one side will be longer than the other and you’ll end up with an unsightly gap in the long wall. The trick: Use stakes and string to layout the bed before you install the blocks.
The only thing harder than squaring the corners is levelling the blocks all the way around the perimeter. Sounds easy, right! After lots of do-overs, I developed a trick: Put down a perimeter of 2″x10″ pressure-treated boards and then stack the blocks on top of the boards. To build a bed that’s 10’x6′ long, lay down two 2″x10″x10′ boards and 2 2″x10″x4′ boards. You still need to level the boards, but that’s much easier than levelling the blocks.
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Replenishing the compost in each of the raised beds is a yearly springtime chore that’s handled manually. With more than a dozen raised beds, this task is always a workout. Thankfully, compost is much lighter than wet sand. True story: Though I use the wheelbarrow often (almost daily), the tire remained flat for almost twenty years. I never replaced it because the axle was welded into place and I couldn’t get to the tire to replace it (and the tube). And I didn’t really mind the extra effort of hauling a load around (work is work). Finally, I decided to replace the darn thing. After several hours of cutting and welding, a new tire was installed. Wow! What a difference!
Tunneling for a New Soaker System 100717 moved to 2 pages
The hardest part of installing a new soaker system is adding the new plumbing—especially when you need to tunnel under a driveway. Thankfully, we have lots of practice! We used a 30′ water boring pipe (above) to tunnel under the driveways. With practice, the tunneling task only takes about an hour. Note the new 1″ pressure-line (attached to the fence above the raised beds) installed to feed the soaker hoses in each bed.
We chose a soaker system over a drip system because it’s cheaper, easier to maintain, and easy to reconfigure. To provide an even amount of water to the bed, each soaker hose should be less than 50′ long; anything longer results in dry spots in the middle of the hose run. Our 1-hp water pump produces 55 pounds of pressure and allows us to supply rainwater to 9 beds (40 sqft each) simultaneously in 30-40 minutes. To anchor the hoses in the beds, we made 10″ ground stakes from medium gauge wire for about 8 cents each. We added quick-connect hose spigots to each bed so that we can attach a short hose for hand watering.
Update: Though we kept the quick-connect hose spigots (on the pressure line), we abandoned the soaker system in 2018. Why, because it uses twice as much water as hand-watering, and the (above-ground) pressure line is difficult to maintain. Tip: Hand-watering allows us to continually monitor the health of our plants on a daily basis. Any blight or bug problems are spotted quickly, before they have a chance to spread!
Cycling Raised Beds #5 and #6 101017 moved
At the end of a harvest, the steel frame is tilted off of a raised bed and the trellises (and bed) are cleaned. The compost is replenished, the frame is tilted back into place, and the bed is replanted. The large rolling bins are used to haul the leftover stems and roots to the compost pile.
Configurable Trellises and Row Cover Frames moved
Plastic fencing (above) is attached by wires (to the steel frame) to provide portable trellises within the cover frames of each raised bed. These trellises can easily be removed when not needed.
The portable PVC supports for the row cover fabric (sheeting) is clearly visible above. The steel cover frames, some with PVC arches for attaching sunscreen (or string-reinforced plastic sheeting), can also be seen.
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