preparing a raised bed garden

6 things to think about before preparing a raised bed garden

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Are you planning to build and/or install a raised bed? I like to emphasize that raised beds can go anywhere that gets six to eight hours of sunlight a day. And they can be any size you like. However, for the purpose of this article, I’m going to talk about the standard rectangular raised beds that are generally built from untreated, rot-resistant wood (like Niki’s amazing raised bed setup) or concrete blocks, as well as what you might want to think about when preparing a raised bed garden.

When I made my first raised beds, these are a few tips I gathered, as well as things I wish I had thought about beforehand.

Things to think about when preparing a raised bed garden

1. What size will it be?
Raised beds are generally three to four feet wide by about six to eight feet long. This allows you to easily reach into the raised bed from the side to plant and dig and weed, without having to step into the garden where you risk compacting the soil.

The height can also be important. If you are putting your raised bed on a hard surface, like a driveway, or over hard-packed soil, you want to make sure it’s deep enough for plants (especially root vegetables like beets and carrots) to root. If it’s too shallow those roots will reach down into that subsoil (or hard surface) and hit a brick wall. I usually recommend at least 10 to 12 inches.

2. How do you pick the perfect spot?
When preparing a raised bed garden, location is everything, but it doesn’t have to be your backyard. Your raised bed could go in a sunny side yard, your front yard, or even your driveway.

You’ll want to make modifications if you have a slope and assess whether the area drains well. Here are some tips for planning where to put your raised bed.

3. How will you get rid of grass?
Good question because this is a common concern. If you’ve ever tried to cut out and lift sod, you know what an enormous task it is. An easier way to get rid of grass is to outline the space and cover it with a layer of cardboard and cover that with a layer of soil. The grass will break down and voilà! A new garden site. Doing this in the fall will allow everything to break down over the winter.

4. Do you want to install irrigation?
If you want to set up a whole drip irrigation system with a line running from your tap or rain barrel, you might want to do this before your raised bed areas are finished and filled. That way you can run hoses under pathways or layers of mulch, and adapt the bed around where the hose attaches to the irrigation system.

5. How much soil will you need and what kind?
There are some handy soil calculators out there that will help you determine how much you need to fill your raised bed, like this one from Gardener’s Supply Company.

As far as type of soil, I like to emphasize buying the best quality that you can afford when preparing a raised bed garden. When I had multiple raised beds to fill, I ordered triple mix from a local supplier (after chatting with them on the phone about my options) and top-dressed it with organic vegetable compost. I like to recommend leaving some in reserve to replenish your raised beds throughout the season.

6. Should you stake the sides?
One thing I wish that I had done when I built my first two raised beds is install a couple of midpoint stakes to prevent the beds from shifting over time. This is one of my number one raised bed tips!

For more information on gardening in raised beds, check out the following articles: 

Do you garden in raised beds? Share your experience in the comment section below.

Raised Bed Revolution link to book

photography by Donna Griffith for Raised Bed Revolution

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preparing a raised bed garden

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69 Responses to 6 things to think about before preparing a raised bed garden

  1. linda wong garl says:

    When I built my raised beds over 10 years ago…I used landscape fabric but made sure I put the edge of wood on top of the fabric so the grass would not grow into the bed…Also, used cardboard over the top of the landscape fabric…never, ever had a problem with grass or weeds growing through….do those precautionary steps and you will be a happy gardener!!! I heavy bolted the corners and reinforced the inside with a 2 by 2 piece of wood to bolt into…solidly cornered…so they have been perfectly intact …the extra care in the beginning is a long term plus!!! Don’t forget to rotate crops each year…from bed to bed! And replenish with new compost or raised bed organic nutrients ….

    • Tara Nolan says:

      Great tips, Linda, thank you for sharing with our Savvy readers!

    • Carolyn says:

      i want to start a raised beds for next yr so put the weed barrier fabric down,make the boxes, but what do u fill the boxes with besides top soil? and what do u add to the top to prevent the plants from drying out? i want to make mine organic what can u use for bugs? and what flower do u use to keep animals snakes away thank u

    • Susan Cassidy says:

      What do you mean to rotate crops from year to year?

      New gardener

    • Tara Nolan says:

      Hi Susan, It’s a good idea not to plant tomatoes, for example, in the same place every year as pests and diseases can overwinter in the soil. I usually rotate my crops every couple of years or so.

  2. Thomas Brophy says:

    You write that you have filled new raised beds with a “triple mix.” After many years of gardening, I have never heard of such a mix, and don’t believe it is offered by those businesses offering topsoil for sale. So, if you could delineate the components of triple mix, perhaps it could be replicated by gardeners without access to it.
    Thanks.

    • Tara Nolan says:

      Hi Thomas,
      I can’t find the ingredients on the site where I bought my soil (it looks like they are redesigning), but generally it’s a mix of top soil, peat moss, and compost. I called ahead of time and spoke to an employee and felt good about my choice. Mel Bartholomew, who perfected the square foot gardening method, recommended 1/3 perlite or vermiculite, 1/3 peat and 1/3 compost and within that compost, he said to include 6 different types of compost.

    • Thomas Brophy says:

      Hi Tara, thanks for your reply. Sounds like a good general mix, except holy, holy 6 types of compost? Jeez! Lol. I’m thinking probably many roads lead to Rome, so to speak. So, my general compost, of which there never is as much at the end as I had hoped, plus straw duck bedding and manure, plus my home-made fertilizer of fish frames, heads and guts, molasses, kelp, etc. hopefully will do.
      Thanks again.

  3. I am planning to grow vegetables as grocery are becoming expensive and it is healthy to have your own grown food. In modern time un-ethical fertilizers are being used in agriculture and to protect our family from this poison, raised bed garden gardening is important.

  4. Tara Nolan says:

    Hi Thomas, I know! That is a lot of different types, but your mix sounds like it’s probably nutrient-rich and just as effective! 🙂

  5. Tyler says:

    I like what this you recommend about buying the best soil you can afford. It makes sense that soil can make all the difference for a garden, especially one without ideal conditions. I’ll have to remember this for my garden because I’m going to completely redo the soil and making sure it’s high quality would be helpful. Thanks for the post!

    • Tara Nolan says:

      Best of luck with your garden, Tyler! I always recommend top-dressing your raised bed with an inch of compost mid-season to restore some nutrients, as well!

  6. Miriam Breezee says:

    Just rented a raised bed at a community garden.
    Added more rich soil. The bed itself has alot of bugs. Should I do anything about this or go ahead and start planting.
    Newbie Gardner! TIA

    • Tara Nolan says:

      Hi Miriam, it’s hard to say what you should do as there are many beneficial insects that live in a garden – not just bad guys! I would go ahead and start planting. And if you see anything happening to your plants, post a photo of the offending insect to a Facebook group to help you identify. That’s what I did recently when my sister had a crazy beetle on her black-laced elder. I discovered it was a bad guy!

  7. Marc says:

    I think you also have to consider what materials to build the raised beds from. If using wood, avoid pressure treated (despite assurances that the new type of pressure treated lumber is not toxic) and consider a more durable wood such as cedar or redwood. I lined my new cedar raised beds with plastic on the inside (just the sides not the bottom) to try and keep the soil from direct contact with the wood. My last raised beds that I replaced with the new cedar ones were just made from pine 2×6 lumber and rotted away in less than five years. The other issue is the corner joints fell apart as the wood rotted so my new beds have extra 2×4 reinforcement on the corners and at regular intervals along the long sides.

    Or if you can afford it use stone. But be aware that the beds will not be easy to move whereas with wood beds you could move them if you had to or at least disassemble them and move them in pieces.

    • Tara Nolan says:

      You are absolutely right! I recommend using rot-resistant wood, like cedar (my Savvy colleague Niki uses hemlock). At the time of writing this, my cedar raised beds are almost six years old and still in great condition!

  8. Shiv Iyer says:

    Just read your fantastic book,”Raised Bed Revolution”.
    Questions:
    1. Since my raised bed (4′ x 12″ x 1′) will be on grass, I will put cardboard on the grass to kill it. If I start now, will it be good for planting in say March/April 2018?
    2. At that time would I still need to add landscaping fabric at the bottom of the raised bed?
    Thanks.

    • Tara Nolan says:

      Hi! I’m so glad you like the book. 🙂
      The cardboard might not have totally taken care of the grass, but it should be on its way. I would say landscape fabric is necessary if you are fighting nasty weeds with deep roots, like bindweed (the bane of my existence on one side of my property), but if it’s just grass underneath, I would just let that cardboard and grass break down under the soil you place on top!

  9. Jen says:

    Hello!
    I have always wanted a garden but the money is never there’re to create a raised bed, I have a feral cat colony so I really do want a raised bed to ensure there’s no kitty waste in my veggies! I would fence it off with some netting I have. My question is, with no really funds to purchase wood I thought I would use left over fence boards form a couple of seasons ago. The problem is that it is treated lumber. Is it safe to use since it has been outside a couple or years? I could look into pastic lining but as I said I don’t really have money to invest and i’ll habe to purchase soil and plants too. Thanks for your post it’s very helpful 🙂

    • Tara Nolan says:

      It’s hard to say if the chemicals have perhaps already leached out of the wood, so I would be cautious planting food if you haven’t lined the inside of the raised bed with plastic.

    • Kelly says:

      What you have should be fine. The chemicals in treated lumber don’t leech that much into the soil, and what little does typically stays in the soil. If it’s too much it will kill the plant long before it reaches a level high enough to hurt you. My beds were made with treated pine and I researched my face off on the topic, and read many studies and many opinions. If your lumber wasn’t manufactured before 2003, it’s fine. I don’t know if they have anything like this where you live, but here in Syracuse you can fill up your trunk with compost made from local yard scraps and food waste for five bucks. Mix that with a big bag of peat moss and some perlite or vermiculite and you’ll have fantastic soil to start growing in! You don’t have to have piles money to have a great garden. Just a will to get it done. 🙂

    • Laura says:

      Kelly had some great suggestions. Another idea, if you have a small amount to invest, is to look at your local hardware store for cedar or redwood fence pickets (6′ dog ear or flat top…I cut the dog ears off mine). I was able to make a 3’x6’x11″ raised bed for $25.00 (hardware and 2x2s for the joints included in that price).

    • Tara Nolan says:

      Hi Laura, That sounds like a great idea! Thank you for sharing it here. 🙂

  10. Lydia Orlando says:

    I have a question about the soil in the raised bed. Should it be removed and new soil put in. It seems like my plants are not doing as good as they used to about 5 years ago. I do put manure in the bed and mix it into the soil that is there.

    • Tara Nolan says:

      Hi Lydia, I don’t recommend removing soil, I usually amend my raised beds with a few inches of compost. I would suggest trying a manure/compost mix or maybe just compost this season!

  11. Jenny says:

    Hi!
    I am so excited to start my raised beds this year!! I am unfortunately starting late down here in GA where it’s already so warm. I wonder, in terms of grass, I am looking to build in a great section of our yard. What do I do about the grass? Could I till it up or should I put something down? I am against the use plastic in our garden, however. What would you suggest?
    I also wonder, since it is so warm, could I just plant seeds and let them go or should I sprout them ahead if time? It’s already in the 70’s here!
    Thank you so much

    • Tara Nolan says:

      Hi Jenny, If it’s late in the season, I would recommend putting cardboard down over the grass and covering with a layer of mulch. Now usually you would leave it for a bit so the grass can decompose, but I say just put the raised beds overtop of the cardboard and mulch and fill with soil! You should be fine direct-sowing seeds in the garden at this point. Check the seed packets to see how warm the soil has to be to plant, but I feel like you should be good. You are SO far ahead of where I live!

  12. Tara Nolan says:

    Hi Carolyn,
    I would make sure that you amend the soil with compost. You could add a light mulch, like straw, which will keep the weeds down and help retain moisture. There are some great charts online that show you what to plant that will attract the “good guy” insects to take care of the bad guys.

  13. Allison says:

    I am adding raised beds to my garden. What height do you recommend if placing on grass with a cardboard/mulch bottom. These boxes are going to be used for tomatoes. Our existing garden has become the shaded area of the yard, the neighbors planted a tree.

  14. Laurie Geiser says:

    I am looking to try a couple of raised beds or containers this year with hopes to do much more next year. The only open, sunny spaces I have are over my leach field, and I am told that I cannot grow food plants there. So, can I grow in large containers that do not allow any root contact with the actual hard clay dirt? If so, do they need to be deeper than the 10-12 feet you advise for raised beds? Should I use a couple of inches of gravel at the bottom for drainage to keep the soil from being too wet? Sorry so many questions. This is all very new to me.

  15. Cynthia Irving says:

    Can I use a tarp under my raised beds to deter weeds and grass from growing. I was thinking I could poke holes in it for drainage?

    • Tara Nolan says:

      Hi Cynthia, I fear that a tarp wouldn’t drain well, even with holes. Also, the weeds will then be able to grow up through the holes. I would recommend landscape fabric, which is permeable. 🙂

  16. Trevis Kelley says:

    Hi Tara!

    Great article. I have been looking into this for a long time, as I have a bad back and would like to have raised beds to give myself an easier time. I am wondering, as it doesn’t seem to be talked about much, if there is a maximum height recommended for a raised bed. I am looking to build my beds to about waist height or in my case about 3 1/2 ft. I am worried about the soil weight, of course, but was thinking I could build my beds with concrete or something like that. Are there other issues I should be concerned about with that kind of a setup? Thank you so much!

    • Tara Nolan says:

      Hi Trevis, I don’t think there is a maximum height. If you are concerned about weight, though, you could fill the bottom half (depending on the depth) with plastic plant containers or water bottles to lightly fill some of that space before filling with soil!

  17. John King says:

    Hi, I’m thinking of building a pair of 8-foot-long beds. Would you recommend in-line braces mid way?

    • Tara Nolan says:

      Hi John, Great question! When I give my raised bed talk (to garden clubs, etc.), one of the things I mention is that I wish I’d put a mid-point stake when building my first two raised beds because they’ve heaved a little with freeze/thaw each year. So yes, I would definitely recommend in-line braces mid-way, especially if your bed is 8 feet long and you live in a region where the ground freezes in winter.

  18. John Alan King says:

    Tara — Thanks! No ground freeze, but better safe than sorry….

    One more question, if that’s okay. Would you sit the raised bed on top of the ground (albeit with stakes to hold in place), or have the wood go down an inch or so into the ground level for mooring? I had a very casual bed that I replaced that I did the latter way, and it seemed the wood had been damaged by boring, bermuda grass working its way in, etc…..

    Again, much appreciated!

    • Tara Nolan says:

      Hi John, generally I’ve just sat the raised bed in place. Some of my raised beds have stakes, so those have gone into the soil to moor the bed in place, but the raised bed itself just sits on top of the soil.

  19. Liping says:

    My biggest concern is my neighbors use herbicides and pesticides. how do you deal with that?

  20. Hannah says:

    Hi,

    I am starting my first raised beds this weekend. They will be going directly on top of soil although I will be using a landscape fabric as a weed barrier. Do you think I can fill my beds with soil from the garden (pathways around raised beds) and then mix with compost bought from garden centre? Alternately will I be ok to use and can you recommend some ready mixed stuff from a garden centre?

    • Tara Nolan says:

      Hi Hannah,
      If the soil doesn’t have weeds in it and it’s pretty healthy, you can definitely use it on the bottom. You just want to make sure you aren’t depositing weed seeds on TOP of the landscape fabric! For mine, I used a triple mix that I had delivered and then top-dressed with compost. If you’d like to make your own mix, Jessica listed some recipes here: https://savvygardening.com/diy-potting-soil/
      Happy gardening in your new raised beds!
      Tara

  21. Lucie says:

    I have found the perfect FREE raised garden beds. As I got older, I could no longer bend to plant or weed and as a senior on low income SS, I needed something CHEAP. As long as you don’t care what they look like, old truck canopies are GREAT and you can find lots of them for free. Just put braces so the back window will not accidentally open. A lot of people will even deliver them, so they do not have to pay a land fill to get rid of them. You have the initial cost of the soil, but after that, they are perfect. I built covers for mine from CPVC pipe and plastic garden fence, both cheap.

  22. Srishty says:

    Hi,
    I have been researching about the terrace gardening options, and i wanted to know if the raised bed method on terraces (or any hard surfaces) would give results as good as beds made on land? And what about productivity? Do the quantities differ? (land vs terrace)

    • Tara Nolan says:

      I haven’t gardened in-ground on a terrace before, but I would say provided you provide the right conditions, your garden can thrive anywhere. Whether a raised bed is placed on a hard surface or dug into the ground, you’ll want to be sure to regularly amend the soil, water, and feed plants with an organic fertilizer. The key is healthy soil!

  23. Kelsey Bourque says:

    Hey I’m looking into making a raised garden bed but I bought my house after we got snow. How would I start this process when the snow melts to bed ready to plant in may? Would I have to dig up the ground?

    • Tara Nolan says:

      Hi Kelsey, You can dig up the grass, which can be time-consuming, or you can use the cardboard trick. Simply place cardboard overtop of the area where you want your raised bed and place the raised bed overtop. Once you fill it with soil, the grass underneath the cardboard will decompose over time. 🙂

  24. Courtney says:

    Hi Tara! I am new to gardening! This year I will be putting in a raised bed. One question, my husband uses fertilizer on our lawn, is this safe for the vegetables I plan to grow in the raised bed??

  25. Courtney K says:

    Hi Tara! I am new to gardening! I will be putting in a raised garden bed this year. One question, my husband fertilizes our lawn, is this safe for the vegetables I plan to grow? Thanks!

    • Tara Nolan says:

      Hi Courtney, I would say it depends on what he uses as a fertilizer. If it’s chemical fertilizer, I would definitely keep it far away from the raised beds. If it’s organic, I wouldn’t be as concerned, though you still want to keep it away from your crops. Lawn fertilizers are more focused on nitrogen, which can encourage leaf growth, but not the actual edible or the roots. Happy Gardening! ~ Tara

  26. Joy A says:

    My daughter wants to build some raised beds in our back yard. Right now, our small yard is completely gravel/river rocks, and was recently (about a month ago) aggressively sprayed with weed killer/pre-emergent that is supposed to prevent new growth for a year. Can we now do raised beds without everything she plants dying? Would we just need to do taller beds (so, move the rock, lay down landscape fabric, and build a bed 12-18″ high)? Also, the only place we can put the beds is along a stuccoed block wall, which I know retains lots of heat during our Phoenix summers (and late spring and most of fall, actually). Is there something we can place between the bed and the block wall to insulate it so the plants aren’t fried? I’m completely new to doing ANYTHING with plants or gardens, and would like to have this project not set up for failure from the very start. 😉 Thanks!

    • Tara Nolan says:

      Hi Joy,
      Raised beds would certainly allow for you to control the soil that’s put inside, but I can’t say for sure that your crops won’t be affected by spray residue. I certainly wouldn’t spray in future if you plan on growing food. If you’re concerned about the heat, you can get shade cover that you can put over the raised beds.

  27. Beyoung Yu says:

    Lots of great tips here. I’ve just finished building a 12 ft long cedar raised bed that’s going to go along my fence. Last summer I had previously removed all the grass in my side yard and covered it with landscape fabric and crushed gravel. I’m wondering if it’s necessary for me to place more landscape fabric under the raised beds that will be sitting on top of gravel from last summer. Do people do this to ensure soil doesn’t spill out of the bottom or is this only to prevent weeds?

    Thanks !

    • Tara Nolan says:

      I’m not sure it’s necessary to add more landscape fabric. If you nestle the raised bed into the gravel, the soil shouldn’t come out. I would say the main purpose of the landscape fabric would be for weeds, which you’ve taken care of under the gravel. 🙂

  28. Rahel says:

    I am thinking of trying this next year. Do you rotate the soil out yearly, or add fresh stuff? How do you prepared the soil as you don’t use a tiller? Also, do you need to buy smaller plants for these types of gardens? I just have a big regular type of garden, but am just starting to read up on this method and I think the fact that this type of gardening has way less weeds is very intriguing to me.
    We are a family of 6 (all boys) so I also wonder if this is a good way to go or if there is another method??
    Thank you!! 🙂

    • Tara Nolan says:

      Hello! No need to rotate the soil, just be sure to amend with compost in the fall and/or spring. Here’s an article I posted yesterday about soil: https://savvygardening.com/the-best-soil-for-a-raised-garden-bed/

      With a raised bed, you won’t need to prepare the soil underneath, unless it’s very shallow. You should be able to just fill and start planting.

      Depending on the size of the raised bed, you should be able to plant regular varieties, but there are smaller, more compact varieties for small spaces.

      I think raised bed gardening would be absolutely fine for a big family – you might even want to build more than one!

  29. RD says:

    Hi Tara
    I have been sticking to container gardening till now but have some large shrubs at the moment which i want to plant into the ground – namely hydrangea, pieris, some rose, black elderflower. I wanted to make a raised bed because they are currently sitting in pots that are about 15cm deep. I am not sure if i will find good soil if i dig that deep into my garden. I think if i make a raised bed with compost, i might need to wait a season before transplanting them, since the soil might need to settle down & become firm to hold them…What do you reckon?

    • Tara Nolan says:

      Hi RD, it’s true, if you just fill with compost, it might be really light and fluffy when you try to dig in a big shrub. But you might see success if you even leave for a few weeks. You might also want to add some bags of garden soil. If your beds are shallower and the shrubs will be reaching into the sub-soil, provided it isn’t hard-packed, they might stay in place.

  30. aliyanajohnn says:

    Such a useful post you shared. The tips you discuss in your content is so informative for everyone.

  31. m winsor says:

    I am building my second 20’x4’x15″ raised bed now. The one I built last spring was placed on top of landscape fabric, lined with cardboard, then a 6″ layer of horse manure mixed with the fall leaves from the year before, covered with another layer of cardboard, then filled with Triple Mix, amended with azomite and limestone. Initially, the ‘soil’ was almost too fluffy (young plants could be dislodged even with gentle watering) but it became more dense as the summer progressed, which was a good thing. However, healthy, tall plants (e.g. okra, Brussels sprouts, broccoli, dahlias) fell over during high winds (wind speeds around 20 mph). Of course, I tried staking them but didn’t want to drive the stakes through the landscape fabric. The soil was not compact enough to support the stakes when the plants were tied to them. I was able to tie some stakes to the PVC arches I had built into the frame at 3′ intervals, but not all were close to an arch (so they just kept on growing where they fell.)
    In the fall I discovered that these plants had very long main roots which had curled around when they reached the landscape cloth at the bottom of the bed.
    Has anyone else encountered this problem? Did you find a good solution?
    Is it better to eliminate the fabric barrier so the varieties with deep roots can be well-grounded?
    I am loathe to eliminate the barrier because we are plagued with quack grass in this area, a very invasive plant which spreads by sending out tough roots. Raised beds are a wonderful solution, except for the toppling plants.

    • Tara Nolan says:

      I have encountered this issue with landscape fabric, as well. It’s great for shallower plants, but doesn’t allow for things like tomato cages, etc. What you could do is remove the landscape fabric and if you think quack grass will still be a problem, smother with cardboard instead, which should smother the grass and in time, break down naturally. And you can put stakes through. 🙂

  32. Jennifer says:

    HI Tara, Thanks for such great tips!! We are seriously thinking about putting in raised beds to start a garden. I have been doing a ton of research and I’m excited. Although, we do not use any products on our lawn for years… and are on .30 property…. we have neighbors that do. Our garden like I said will be raised. Can any products they use or the neighbor two doors down from us that has a company come in to spray his backyard not to get insects affect our garden? Signed, truly concerned about this before we begin. Thanks so much!

    • Tara Nolan says:

      I understand how drift from chemicals can be a concern. The fact your neighbor is purportedly using an eco-friendly product is encouraging. I’m not able to say whether there will be residue in your garden. You could see if a soil test yields anything.

  33. Jennifer says:

    Let me add one tidbit to my last question- the company our neighbor uses is JP McHale who claims to use eco-friendly products to rid the mosquitoes issues.

  34. We recently started a small landscaping company in our town and came across this article. The mulch calculator was a big help because it seems like each yard or flowerbed we do has different depths and sizes. Thanks for the info! Do you have any recommendations for mulch in high altitudes where the temperatures are extreme?

    • Tara Nolan says:

      Unfortunately I’m unfamiliar with high-altitude gardening, but your local garden center or nursery should be able to provide some insights! 🙂

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