Questions regarding raised beds

[Lolapeg91]

Hi All,

So far I have only ever grown in pots. But this year I am getting my garden sorted and really wanted some raised beds. I have a few questions if someone can give me some advice.

1. Do I need an insert inside the raised bed or do I just fill it with bagged soil and allow the roots to go into my garden soil?
2. Do I need to test my garden soil first?
3. Do you have to renew the soil every few years or do anything to it? I know I have to do crop rotation.
4. Do you recommend wood, metal or another material?

Thank you

[Jungle Jane]

My wooden raised bed lasted over ten years,no insert,it’s the base of the wood in contact with the soil that begins rotting first & the corners if you stand on the edges a lot I think wood looks nicer than plastic,I would use wood again it’s more natural looking. I’ve never tested my soil,if weeds grow it’s fine. I’ve only changed the soil in it to grow onions repeatedly,crop rotation you wouldn’t need to do that. Are you thinking of three of four beds or something,I’ve just got one,most my crops are just in a free bed with no sides,shrubs next to them

[Lolapeg91]

My wooden raised bed lasted over ten years,no insert,it’s the base of the wood in contact with the soil that begins rotting first & the corners if you stand on the edges a lot I think wood looks nicer than plastic,I would use wood again it’s more natural looking. I’ve never tested my soil,if weeds grow it’s fine. I’ve only changed the soil in it to grow onions repeatedly,crop rotation you wouldn’t need to do that. Are you thinking of three of four beds or something,I’ve just got one,most my crops are just in a free bed with no sides,shrubs next to them

Thank you for your reply. I agree I think wooden ones look nicer too. I'm not sure how many yet. Can you grow carrots in the lower raised beds? Or are those better for the planters that have some height to them?

For the lower raised beds I want to grow cabbage, toms, cucs. What height is best 15cm or 30cm?

[Jungle Jane]

You could try carrots in there I only grow carrots in containers,never tried in the raised bed. With carrots they can grow alongside a lot of different plants like lettuce,tomato,peas etc so you could put carrots alongside something else in the bed. I always thought carrot fly,fly low & when in containers they’re a bit more higher up for protection? I’m in a garden though,never had carrot fly,they might not know about my carrots I don’t know?

[Penellype]

I like wooden raised beds which I think look more natural in a garden, although I also have some of the plastic ones which are much easier to put together. I find these tend to bow in the middle, even if they are fairly small. I have never tried metal ones.

With regard to lining them, it depends a bit on what you are putting them on. If you have trees nearby you may find the roots under the beds grow upwards into the nice rich soil and steal nutrients and water. It is surprising how far from a tree or hedge this can happen. My hotbeds are a good 10 feet from the allotment hedge (hawthorn and blackthorn) yet I get roots growing into them. The roots from the leylandii hedge at home are much worse, and the beds near it became unworkable within a few years. It doesn't matter with the hotbeds as they are emptied every year, but in a permanent raised bed you might be better with a lining if the bed is near trees. I lined my permanent raised beds at the allotment with cardboard, which rots down within a year. The worms then mix up the soil with the contents of the raised bed, which in my case started off with a mixture of rotted horse manure, grass cuttings, paper, coffee grounds and used compost. Deep rooted plants such as parsnips and large carrots will struggle in a lined bed unless it is very deep.

I didn't bother testing my soil, except for the bed I used for blueberries, when I did a pH test. You don't need to change the soil, but you will probably find that the soil level will drop over time especially if you add a lot of organic matter. It is a good idea to mulch the bed with compost or some other organic material every year, and I always add bfb at planting time to add nutrients.

Every garden is different - I manage 3 distinct areas within a couple of miles of each other and the differences in what I can grow where are staggering. The only way you will find out what grows best in your beds is by trial and error. With regard to carrots in particular, I have found them impossible to grow in raised beds, not because of carrot fly but because the seedlings are usually completely eaten by slugs before they have more than 2 leaves. I grow my carrots in 30 litre buckets with copper tape round to deter slugs and a net over to prevent carrot fly and I get a decent crop that way. Other crops will tolerate being grown in modules and planted out when they are big enough to cope with the slugs, but carrots are likely to fork or become distorted if you try that.

[annie8]

We built wooden raised beds about 6 years ago. I will get a pic and post later. We didn’t line and initially filled with bulk bags of compost. I top up every so often, using my own compost or occasional additional bulk bags. They are low beds not very high. In terms of carrots I do grow them and have got better at avoiding forking. If you pick types that are more on the stumpy side rather than the long types that helps. I also make sure I dig the bed over, which I don’t do that with the others and remove stones that I find.

[jools]

I was about to post a similar thread to this, so thank you Lolapeg and to everyone who has answered. I hope it's okay that I ask some questions of my own here, rather than start a new thread.

I have already bitten the bullet as I have just bought three raised beds (1 of 4ft x 4ft & 2 of 6ft x4ft - about 16ins high) which I am putting together in a right angled shape. I am concerned about them rotting. Mine will be directly on soil and I shall be painting them, so I'm hoping that will provide some protection. If it is the ends and the corners that rot first, will it help if I raise them off of the soil a little by putting bricks underneath? Or perhaps pebbles?

I am going to splash out a little more by buying a net cover to keep out the slugs, snails and butterflies, but probably just for one of the 6ft beds. I want to grow purple sprouting broccoli, cabbages and cauliflowers, but I'm not sure how many plants I can get in one 4x6 bed!

[rary]

I have used concrete paving slabs for three sides of my raised beds and the remain side of one is made with tin sheeting and the other is wood which I lined internally with plastic sheeting to keep the moisture off it, I also painted the outside of the wood with a preservative, my beds a two feet deep, one sitting on concrete, the other sits on a double layer of weed membrane, this is to try and stop tree roots, as explained by Penellype above, my beds are only 4 ft. away from trees and hedges, so far it this has stopped the roots getting in, I use seaweed, home made compost and recently started adding vegetive waste straight onto my bed, this I think will add all the nutrients into my soil rather than trying to catch them from a compost bin

[Ger-annie-um]

I, sort of, do the same as Rary in that I line the inside of my wooden raised beds with plastic sheeting.........old compost bags turned inside out and stapled to the wood usually. Good job I use a lot of compost, my raised beds are 3m x 1m x 0.5m high and I have 4

[Penellype]

I was about to post a similar thread to this, so thank you Lolapeg and to everyone who has answered. I hope it's okay that I ask some questions of my own here, rather than start a new thread.

I have already bitten the bullet as I have just bought three raised beds (1 of 4ft x 4ft & 2 of 6ft x4ft - about 16ins high) which I am putting together in a right angled shape. I am concerned about them rotting. Mine will be directly on soil and I shall be painting them, so I'm hoping that will provide some protection. If it is the ends and the corners that rot first, will it help if I raise them off of the soil a little by putting bricks underneath? Or perhaps pebbles?

I am going to splash out a little more by buying a net cover to keep out the slugs, snails and butterflies, but probably just for one of the 6ft beds. I want to grow purple sprouting broccoli, cabbages and cauliflowers, but I'm not sure how many plants I can get in one 4x6 bed!

I would be careful with painting them as some paints are not very nice and are probably best kept away from areas where you grow food.

[rary]

I am going to splash out a little more by buying a net cover to keep out the slugs, snails and butterflies, but probably just for one of the 6ft beds. I want to grow purple sprouting broccoli, cabbages and cauliflowers, but I'm not sure how many plants I can get in one 4x6 bed!

I doubt that any netting will keep slugs out jools, if you want to control slugs without chemicals, you can use beer traps, or nematodes, which you can make up for free, a garlic spray or collect them at night for disposal, don't just chuck them over the fence as they will make their way back into your garden

[Jungle Jane]

I would still put the raised bed on the soil,my raised bed is really,really old maybe over fifteen years,I still use it in my crop rotation. Its only two corners that’ve gone,I used mud to hold it in place,the base of the wood doesn’t notice unless you lift it up. I get a lot of leaf fall on that side,being covered in wet leaves every winter must help the rotting process.
Maybe putting on bricks would make it last longer but pebbles would slide into the bed over the years,weed matting tears after so many years. Ive had wooden planters on the patio,painted with inserts but still rotted after 10+ years.
Id have them straight on the soil but check there’s nothing around the sides that would help it rot,if there’s a build up of mud etc.
Also copper tape around the wood stops snails,it was tape from the garden centre (I got some cheap stuff once but it didn’t stick in the rain it curled at the edges) the tape from the garden centre stayed stuck down for years until the collapsed side.

[hamesy]

Whenever I build raised beds, I usually fill them with compost and organic matter, no need to insert anything into the beds. You can start with a layer of cardboard and them fill with compost as the cardboard will help kill any weeds. Every year, I top up the soil with homemade compost or well rotted manure.

You can build your raised beds with whatever you've got lying around really. In the past I've used broken down pallets and scaffold boards. This year, I've started to build a load of new raised beds and used pallet collars.

I have seen a few people mentioned Birdies raised beds which are made out of metal and I've seen a few YouTubers rave about them.

[Lolapeg91]

I have used concrete paving slabs for three sides of my raised beds and the remain side of one is made with tin sheeting and the other is wood which I lined internally with plastic sheeting to keep the moisture off it, I also painted the outside of the wood with a preservative, my beds a two feet deep, one sitting on concrete, the other sits on a double layer of weed membrane, this is to try and stop tree roots, as explained by Penellype above, my beds are only 4 ft. away from trees and hedges, so far it this has stopped the roots getting in, I use seaweed, home made compost and recently started adding vegetive waste straight onto my bed, this I think will add all the nutrients into my soil rather than trying to catch them from a compost bin

I would be having my raised beds about 10-12ft away from the tree base (there's 2 large trees in my garden) would this distance be ok to not put sheeting down?

[rary]

I honestly don`t know if that would be far enough to avoid root ingress, but personally I would still put a barrier down, using weed membrane might prevent the roots getting in, I found a double layer,with no joints or holes in the sheets to be the cheapest way of doing this, so far it has worked, it might be worth your while searching for second hand landscape matting, what ever you do I wish you well in your gardening