How to Build Raised Beds for Your Vegetable Garden (2024)

Comments

"My potatoes and carrots never grow in compost why the carrots always curl up and the potatoes have green age but no toobersgrow "
Eileen Miller on Thursday 11 August 2016

"Root crops like carrots need deep soil, so they may curl if the compost is too shallow. Roots can also split or take on odd shapes if the soil is overly rich - for example if lots of manure has been added before sowing. Potatoes need to be earthed up by drawing up the soil around the stems to create more 'space' for the tubers to grow in. Keep potatoes well watered in dry weather too."
Ben Vanheems on Saturday 13 August 2016

"my bed is built on decking planks with no gaps . Soil will be good 16inches deep. Do I need any sort of lining, or drainage like broken crocks?"
Charlie T on Sunday 16 April 2017

"Hi Charlie. It might be a good idea to line the bed before filling it with your soil. This is so that the decking planks underneath don't rot, but also so that any preservative/treatment used on the decking doesn't leach into the soil and then into the vegetables you grow in it. You will need to puncture the lining at the bottom to allow for drainage (unless it is naturally draining)."
Ben Vanheems on Tuesday 18 April 2017

"I am looking to make a raised veg bed in my garden, is it advisable to place a layer of broken stones to help drainage? Also is it advisable to use a weed protector membrane across the whole base or just at the edges?Thanks"
Mark on Thursday 5 October 2017

"Hi Mark. There's no real need to put broken stones to help with drainage. Just having the soil level within the beds raised above the surrounding ground level will help it to drain. With regards, weed protector membrane, you can use this to hold in the soil if you are placing your raised beds onto a hard surface such as paving. Otherwise I wouldn't say it is necessary - though some people like to lay membrane between beds to help stop weeds sprouting up along the paths."
Ben Vanheems on Friday 6 October 2017

"Another drainage question!I plan on putting a liner in my planter as it's built with treated wood. Should I drill holes in the bottom so that excess water can drain out? "
Brant on Monday 16 April 2018

"Hi Brant. It depends on what you're lining it with. If it's a non-permeable liner, then you will definitely need to make holes into the bottom of it to allow excess water to drain out. And I'd make quite a few so that there's no risk of water collecting at one end. If it's just a traditional raised bed you are making, then I'd even consider cutting away the liner from the bottom of the bed entirely, so that just the walls and a short area on of the bottom away from the walls are lined."
Ben Vanheems on Tuesday 17 April 2018

"What base do you need to put on the bed? Just a thin section of plywood?"
Mark on Wednesday 2 May 2018

"The planters are made from old fence boards, so there are some little holes here and there, and a couple places where the boards don't meet completely. I was planning on using a liner. So maybe I'll consider not putting the liner on the bottom."
Brant on Wednesday 2 May 2018

"Hi Mark and Brant. Generally there shouldn't be a need to put a bottom to the raised beds. The soil within the beds is best kept in contact with the soil it sits on top of, so that microorganisms, worms etc can move freely to help improve soil health. The simple idea of the beds is to add additional depth of planting area, for all the reasons described, but not to isolate the bed from the surrounding area.The only time you might consider adding a base or bottom liner is when you want to isolate the bed from its environment, perhaps, for example, because it is sitting on polluted ground or on a hard surface such as tarmac."
Ben Vanheems on Thursday 3 May 2018

"I'm building my raised beds on the site of an existing lawn. Would you advise removing the layer of lawn that will sit underneath the compost or can I simply pile the compost on top of the grass? The surrounding grass will form the footpath, is that sensible? Also, As I'll end up using treated wood and line the sides as a precaution, should I use a non-permeable lining? and if so will the trapped moisture affect the crop growth?"
David on Friday 21 September 2018

"Hi David. You can put the compost straight onto the lawn. I made beds like this earlier in the year, but just to be save I first put a layer of plain brown cardboard over the grass, onto which the compost went. I had no re-growth of grass at all. Grass is fine as the footpath, but mowing it may be a nuisance, so you may eventually decide to move to bark chippings or similar. Lining the wood is fine. I wouldn't bother going right under the growing area though, just the wood sides. In this way it shouldn't trap soil moisture to cause a problem."
Ben Vanheems on Friday 21 September 2018

"Can I put the raised bed on a patch of concrete I have spare and should I place a membrane on ground to stop any weeds but that will let water through. Thanks"
Rod Fransham on Sunday 25 November 2018

"Yes, you could put a raised bed on concrete. It would be advisable to line the base and sides of the bed with a permeable liner/membrane (that let's moisture drain through). This way all the soil/compost you put in it won't wash out over the concrete. "
Ben Vanheems on Monday 26 November 2018

"What would be the best lining material to protect the boards at the sides?"
Jordan on Monday 7 January 2019

"If you choose not to use a wood that is durable, and prefer not to treat the wood, then a lining material will help the wood to last a little longer. For this a tough, long-lasting liner is ideal, which can be gun-stapled onto the wood. I would recommend a pond liner-type material such as butyl for this."
Ben Vanheems on Monday 14 January 2019

"I'm building a garden on my roof and wondering if I put a narrow planter against a wall to maximize my space. It would be 24" deep and 12" wide, and I would use to grow summer crops like chinese long beans, bush beans, and radishes in winter.Thanks!Xochitl"
Xochitl on Saturday 28 September 2019

"Hi Xochitl. That would probably work very successfully, yes. Or you could perhaps use planters that are slightly wider - say 18", but less deep. You don't really need the planters to be much deep than 12", unless you want them taller for ornamental reasons and so there is less bending. Please check that your roof is strong enough to support the extra weight of your garden - soil/potting mix can get very heavy when wet."
Ben Vanheems on Monday 30 September 2019

"HiIf i have untreated Oak bedding 2" thick how long could it last without a liner.Also if i use a liner for just the wood and leave the base clear - what is the safest (non or porous) and is there a type of liner to use that wont leak any phthalates or BPA etc "
kevin on Thursday 20 February 2020

"Hi Kevin. I can't give an exact answer on how long untreated oak would last, but at two inches thick - which is nice and thick - it should last several years I'd imagine. Certainly a liner would help prolong the life of the wood, and for this I'd use a standard rubber/butyl pond liner, which shouldn't leach out nasty chemicals."
Ben Vanheems on Friday 21 February 2020

"Hi there,We plan to build a raised sleeper bed (30-40cm high, 0.5-2m width, placed on top of ground) round three edges of our garden. The back is an old building wall, the other two sides are fenced. How would you build these beds against the fence? We weren't going to put a backing on the beds at the wall.Looking forward to hearing your advice!Lorna"
Lorna on Thursday 23 April 2020

"i'm building a raised bed (6' x 4' x 21") it will be sited on our paved patio area, should i line it, i have some old tarpaulin so could use that and would you recommend slitting holes in the bottom before filling with soilthanks"
richard on Monday 15 June 2020

"Hi Richard. You don't have to line the raised bed, but lining it will prevent too much soil seeping out from the bottom and potentially staining your patio. If you do use tarpaulin I would slit plenty of holes into the bottom for drainage."
Ben Vanheems on Tuesday 16 June 2020

"I am building a raised bed 3m x 1m for general vegetables what depth should it be and can I place this directly on the grass?Thanks Dave"
Dave Riach on Thursday 25 June 2020

"Hi Dave. I would recommend a minimum depth of 15cm, though you could go a bit shorter at 10cm if weeds/grass are taken care of. You can put beds straight onto grass, yes. You can lay a layer of cardboard sheeting over the grass to help kill it off beneath the growing medium that you fill the beds with, though if you are adding a minimum depth of 15cm this isn't always necessary. But if you can, I'd add overlapping pieces of cardboard to ensure the grass does die off and not poke up at the surface."
Ben Vanheems on Thursday 25 June 2020

"helloim hoping to build a raised garden bed next year for veggie. i would like to build them about 1.20 m high. my idea was to layer old paving slabs in the raised beds about half way then top up with earth and compost. Would this work? My reasoning is I need to get rid of the slabs and thought this maybe a good idea and save money on earth and compost "
janice on Monday 27 July 2020

"Hi Janice. Yes, that would certainly work. You'd just be raising the ground level right up. Bear in mind that the roots will be limited to just the earth and compost that sits on top of the paving slabs. In traditional raised beds they would be able to root into the soil below. You might want to consider giving the slabs away on a local listings site? Someone might be able to make use of them."
Ben Vanheems on Monday 27 July 2020

"I am planning on making two raised beds for the back of my garden and was thinking of using scaffold boards (22mm heigh). I was going to coat them with "Ronseal One Coat" first to protect them but am concerned the ronseal may leach into the soil causing problems for the plants. Do you think this will be suitable or would you recommend another wood preservative?Thanks ..... "
Keith Watson on Friday 23 October 2020

"Hi Keith. This may be okay for the outside of the bed, but to be honest I'd give it a miss. You want to preserve your wood with a non-toxic wood preservative. There are a few choices out there - so take a look and choose one that specifically mentions raised beds if you can. You could chance it with the Ronseal, by lining the inside of the beds with some sort of plastic. But a non-toxic preservative would be a lot easier and kinder to the soil too."
Ben Vanheems on Saturday 24 October 2020

"Hi, I am building an 18feet long raised garden bed on a gentle sloping front lawn (with no bottom). Would you recommend that we level the lawn with soil or gravel for a straight even surface to build on?"
Anju Chauhan on Tuesday 16 March 2021

"Hi Anju. You could either build up one side of the bed much higher, to compensate for the slope. Or, probably easier and more appealing visually, cut the bed into the slop, by digging into the slop in order to achieve a nice, level base for the bed. Doing this would also remove the layer of lawn, though there's no reason you can't just put the soil that goes into the raised bed directly on top of the lawn."
Ben Vanheems on Wednesday 17 March 2021

"I am converting part of my 45 x 45 ft garden plot from row crops to raised beds. The soil, while greatly improved already, is mostly clay underneath. There is a slight slope to the site - just enough so the plot actually drains pretty well despite the clay underlaying. I'm going to start with 4 beds, 4ft wide and 36 ft long. Question is, how to orient the beds to the slope. Do you recommend building the beds across the slope, OR along the slope line? "
John Conrad on Monday 27 September 2021

"I would build the beds along the slope line, so that they look like traditional terraces. This way the beds will be easier to build, naturally lying along the contours of the slope."
Ben Vanheems on Tuesday 28 September 2021

"I want to avoid kneeling because of arthritis Could raised beds be at almost waist level 70 / 80 cm and what construction methods would be practical ?Thank you"
Atholl M Truesdale on Sunday 30 January 2022

"What's the ideal depth of the raised bed for different types of vegetables and greens. Would a 2 tiered 4x4 be sufficient for a variety of vegetables - like carrots, beetroot, gourds, beans, pumpkin, spinach/lettuce, brinjal, capsicum, tomatoes, potato, peas, chillies"
Krithika Natarajan on Wednesday 30 November 2022

"Hi Krithika. The minimum depth for most vegetables and greens would be about 8in (20cm), with some preferring 12in (30cm). If the raised bed is placed onto soil/lawn then the raised bed can be much shallower than this, as the roots will go through into the soil below. If the bed is going to be on a hard surface such as paving you will need to make sure you get the correct minimum depths. A two-tier bed sounds like it should have enough depth to it. You may want a bigger area than 4x4ft (1.2x1.2m) to grow all of those vegetables you list, but a bed that size will certainly enable you to grow a reasonable selection."
Ben Vanheems on Thursday 1 December 2022

"Hi if I use a lining the same as pond liner. Do I need to put holes in it?"
Audrey on Tuesday 16 May 2023

"Hi Audrey. Ideally a raised bed would go on top of soil/grass, so wouldn't need to be lined at all. But if you do need to line the bed, perhaps because its on a hard surface then yes, you would need to make holes into the bottom of the liner so excess water can drain away freely."
Ben Vanheems on Wednesday 17 May 2023