OK, so Tom Scud and I live in a typical Chicago three-flat, and I seem to be the only one interested in major garden improvements (it’s a condo building, and the neighbors seem pretty much not to care what I do). The soil is terrible, dense, clay with rocks – I couldn’t even get mint to grow there last year, for chrissakes! I tried planting a bunch of iris bulbs a couple of years ago, and they have yet to bloom – they send up long, skinny green shoots, and then nothing happens. The tulips and crocuses have survived, but they look kind of anemic.
So it seems to me that the best bang for the buck/effort expended would be to build some low raised beds along the edge of the front walk and along the front and south edge of the building, where there are currently dirt beds now that aren’t doing much. There are a couple of shrubs in the bed next to the front walk, and the aforementioned iris/tulip/crocus bulbs, but that’s it. I was thinking of building some not terribly deep (maybe 6”) raised beds, filling them with some better-quality (purchased) topsoil than what’s there now, and planting a bunch of flowers, preferably perennials. Then I was thinking of putting a couple of large planters on the side of the front stairway, and filling those with more flowers in the front, and maybe some herbs in the back.
Any tips on materials/construction, etc. for the raised beds? We have basic tools (cordless drill, hammers, etc.), but I was thinking of having wherever I buy the lumber do the basic cutting – our downstairs neighbor can get us a power saw, but I’m not terribly handy and would rather not bother if I don’t have to. Any input cheerfully welcomed!
The only raised beds I’ve ever made have been constructed out of old railroad ties. Those might be a bit heavy for what you want, but they work very well.
That’s not a half bad idea. My dad built us a sandbox that way when I was a kid, and he’s an engineer. I don’t think we’d need anything high-tech. But can one buy those at a regular lumberyard? Dad worked for a train company, so availability was not an issue.
I wouldn’t use railroad ties if you want to plant vegetables. Those things were treated with creosote and other chemicals you don’t really want leaching into the soil. Go with cedar instead.
You can use 6x1 boards, but the beds will last longer with 6x2 or 8x2 (or wider, depending on how much you want to raise them). Use 4x4 posts for the corners.
Keep in mind that 6" is not deep enough for many plants. If you want shallow beds, pick plants that will be happy there; if you want specific plants, make sure the beds are deep enough. Many plants with bulbs want to start off 6" deep, and need another 6" for roots.
Whether you go with railroad ties or cedar, it’s a good idea to put a plastic barrier between the soil and wood. This will discourage wood-eating critters and reduce the moisture that the wood is exposed to. If the plastic barrier is tight enough, it might eliminate the problem of things leeching into the soil, though I’m not sure I would count on it for that.
You can also look at cement retaining wall blocks like these. These blocks are a lot thicker than wood, so they’re not a good choice for long, narrow beds. But they do last forever.
There are ways to improve your existing soil if you’re willing to do enough work - sift out the rocks, mix in some compost, etc. - but a raised bed might wind being less work since you can just buy good soil to start with. Or you could combine your efforts (say, improve the top 6" of the old dirt, and build up 6" to give yourself 12" total depth).
Second this. I have had good luck with adding 6" of “pure” compost and mixing it in to the top 6" of existing soil for 12" of nice planting soil. If your soil is truly clay you might need a little more than just compost (like sand and/or lime), but if it’s only finer-grained packed dirt then compost will probably loosen it up enough.
Gypsum is the best way to break up clay. You can do a simple soil test to see how much clay you actually have by putting a little detergent in a mayo jar adding about 2" of soil then filling it with water and shaking it up. It wll settle in layers of sand, silt and clay, I believe your clay will be the top layer. That being said clay soils will work great for gardening but you may need to fertilize along with some compost.
Creosote or pressure treated lumber will last forever. Do not plant food in these boxes.
1 x 8 or 1 x 6 cedar planks (basically fence material) will blow out on you if you make the box too wide. 2x8 will hold up–keep in mind 2x8 is really 1.5 x. 7.5 I made such a box for my deck–it is mighty and looks nice, but it is also like 8 feet long and 2.5 feet high, 2.5 feet deep. Visually it doesn’t scream “OVERBUILT.”
Lining with plastic will give you drainage problems–I murdered my first group of honeysuckle plants after 3 days of heavy rain that way.
Most bulbs want to be planted 4-6 inches deep. Your box will need to be more like 1 foot deep at least to make them happy.
Don’t go with straight topsoil, it’s too heavy/dense and doesn’t drain or hold moisture well. Try a mix of like 50/50 topsoil & compost, or straight compost. Drainage is good to prevent drowning, obviously, but it also allows fertilizer to get deeper.
As an alterntative building material you might try synthetic deck materials like Trex. It’s plastic & considerably thinner than the wood equivalent and at least as strong. I think it looks like poo, though.
If you’re building a box, consider running a drip hose/soaking hose right through the side about halfway up the height of the dirt. Gets water to the roots where it’s wanted, you can put it on a timer, etc so you never need to think about watering, etc. and doesn’t spray all over the walkway.
Several years ago I built four raised garden beds. I used 2x12 rough cedar, joined with 4x4 finished cedar posts. All the beds are two boards high (24 inches) and capped with 2x6 finished cedar. The beds are lined (sides only) with silo plastic (ask a farmer!). The three smaller beds are six foot square; the larger bed is 15 feet on its longest side.
To ensure proper drainage and so that the beds don’t ride up with frost heaves, I actually dug down a foot below grade where the rails would rest. I lined the trenches with six inches (depth) of fine gravel. Then I placed the raised bed into the trenches, leveled it, stapled the silo plastic on the inside and filled with dirt.
Damned flowers and veggies overrun every year now. I just love it!
Do you have anyplace you can dump soil? Because I’d recommend removing several inches of the clay/topsoil and replacing it. Actually, here’s what I’d do:
Remove 3-6 inches of soil.
Put down landscaping fabric to prevent weeds.
Construct the raised bed walls. (No railroad ties or anything treated.)
Line the sides of the board with plastic (just to prevent them from leaking).
Fill with the cheapest bagged topsoil you can find. You can always supplement it - but you’re going to find you’ll need a TON of top soil to fill it.
If the house/building is old and there is a chance you may plant edibles, a lead test might not be a bad idea. But lets assume no lead.
Building raised beds is a great way to enhance your property. But don’t limit yourself to only wood beds. You can build raised beds out of brick, cinder blocks, logs, poured concrete, stacked stone, really only your budget and willingness to build them limits you. In fact you can just build freeform beds that don’t have any walls. Stone and brick etc will last the longest of course. Don’t use old railroad ties, even if you aren’t worried about the creosote, they ooze black tar during the hottest days and that’s just gross.
I agree with everyone above who suggests a foot or more is better than 6 inches, but if you are committed to having them only 6 inches you can double dig and amend the soil with a bunch of compost.
The person above who said do a 50/50 blend of compost and topsoil or all compost is on the money. You don’t need to put down weed barrier however - no weeds are coming up through 6 or 8 inches of soil and if you have weed barrier, no worms will either…and you love and want worms in your beds. If you feel like you simply have to put something down, do a layer of cardboard or 10 - 12 sheets of newspaper overlapped.
Also in between the best leave about 2 feet of space for walking, and none of the beds should be more than 4 feet wide - you want to be able to reach all the way in without walking on the soil.
Don’t buy bags of soil or compost at the big blue or big orange home stores. Instead find your local source of finished compost and get a truckload delivered. Here’s one place to start looking. Also do not get manure. Manure is good for growing plants that you want to be very big and very green like corn. Not bulbs and not flowering annuals.
Remember to plant your bulbs at the right depth, and at the right time of year - for summer flowers you want to plant between Halloween and Thanksgiving.
Also then every spring you’ll want to add 2 - 4 inches of finished compost on top of the beds to reboot the soil for the year.
I built ours out of construction grade 2x10 lumber to prevent bowing. For fastening, I used two systems. At each corner I drilled two appropriately sized holes, then used the cordless to drive in two lag screws. On the inside of each corner I screwed in an "L’ bracket to provide extra stability.
Filled with topsoil, added compost, and anything will grow in there. We use the back ones for herbs and for greens, chives, etc. The front ones have ornamentals, lavender and rosemary.
Wow, looks like I have some reading to do. Thanks to all - it’s really not a lot of space. The largest bed I’m talking about would be about 10’ long and 2.5’ wide. (This is a dense city neighborhood - the whole front yard is maybe 30’ by 15’, and most of that is grass.) I’m not tied to any specific depth or materials - I will have to absorb after I’ve had a night’s sleep, and for sure I’m not going to do anything about it until the weekend. I think brick and concrete are probably more than I’m willing to deal with, though, especially because the spot where the largest bed is is also surrounded on 2 sides by a wrought-iron fence, which could be problematic.
I wasn’t even thinking about lining the wood (or whatever I was considering using to build the beds). Is there a strength or durability reason to do that?
Perhaps it’s to keep any chemicals from leaching into the soil from the wood. I used untreated lumber, so no problems with that. Or it could be to keep the wood from getting saturated with moisture, which can cause wood rot.
The plastic is there to minimize moisture contact with the wood, which helps to prolong the life. If you look at the railroad ties around my house (which are about 35 years old now), you see the difference moisture makes.
The plastic also makes sure that water drains down into the ground rather than out through cracks in the wood frame.
It might prevent chemicals from leeching into the soil, but I wouldn’t really trust it for that purpose.
I do a combo of no dig + tires. I built my garden up one tire at a time and later on added edges and removed the tires. Bonus for the tires is that they are free. I paint them pretty colours too.
I just built about 150 square feet of raised beds in our backyard using these. They’re idiot-proof, which is good cuz I’m an idiot when it comes to carpentry.
You’ll definitely need plenty of compost and coconut coir (soaked) to supplement the soil-- I recommend finding someone who sells worm castings to use as your compost. Phenomenal stuff. You really only need to mix the compost and coir into the top 2-4 inches of the soil, but with a shallow bed, I wouldn’t skimp on buying cheap soil.
Cedar, Redwood and Tamarack are all good, rot resistant woods for outdoor applications, but can be very expensive.
Pressure treated is usually poor quality, splintery and has the drawback of the noxious chemicals used to preserve.
I use regular construction grade lumber and treat it with a coating of paraffin wax. No moisture in = no rot.
Coating the length is not imperative, but make sure you coat all the ends thoroughly. Wood fiber is akin to a straw, sucking water in primarily through the end grain.
It’s also a really good idea on stairs exposed to the large amounts of rain and condensation runoff from roofs. Just make sure there’s no wax on the tread/run face.
This is sort of what I do, I also live in NW Oregon.
Using untreated wood like this will last longer than you would think. You will probably get 10 years or more from untreated 2 X 10s. I am not an organic fanatic, but using treated wood just seems wrong. Railroad ties coated with creosote, yuck.
Depending upon your location, you want to consider drainage and perhaps add some sand to your soil. Here, where is rains so much on the coast, drainage is important or else your soil will never dry out enough to work or warm up enough to plant.
One of the advantages of raised beds is that the soil will warm up sooner than if you just plowed the ground. Keep this in mind when you select what you are going to build the beds out of.
If you use bricks, cinder blocks, railroad ties, then they will retain a cold temperature much longer than a thinner board or material. The borders of your bed can even act as a cold sink to keep your soil cool. You want the soil to warm up fast.
