How to Fill Raised Garden Beds Properly

in this program I'm going to answer a simple question what do you use to fill raised beds I know lots of you have built these beds and now you have the problem of filling them and soil's expensive so you get online and look at other options and everybody's got an idea of how you should fill it what kind of soil to use what kind of amendments to use what do you put at the bottom of a race bed all those questions and we're going to answer all of those in this program now you might have noticed that I'm wearing something special here I just received this and it's the silver award for the best science book of 2023 and it's awarded by the independent Publishers group it's great to win the award but it's a little heavy for wearing around the house anyways I received the award for my book plant signs for gardeners and I think this is a book that everybody should read it gives you the basics of plank roll once you understand some basic concepts of plant growth you'll be able to make the right decisions in the garden you'll be able to read things on the internet and right away you'll know whether they make sense or not a lot of my myth busing is done that way I understand plant growth very well so I can quickly spot the garbage that's out there if you're interested in that book it is available on Amazon plant signs for gardeners now let's get back to the program height really matters with raised beds you need enough soil to actually grow the roots of the plants any bed that is less than a foot tall should be filled entirely with soil now when we're talking about filling a bed there are sort of three different levels that you can consider one is the stuff that goes right in the bottom or even underneath the bed then there's that middle layer a lot of people use bulky material there so they can cut down on the amount of soil and then there's the top layer the the real soil where the plants will be growing and I'm going to divide the program into those three different sections so let's first talk about what goes into the bottom of the raised bed a lot of people put weed barrier down there and why do they do that well they're trying to stop the weeds from growing up into the bed now that doesn't make any sense most weeds won't grow that far in soil the soil will smother them like your lawn grass 3 4 in of soy will kill that grass the same goes for most of the weeds that you might have in your lawn now there are some very noxious weeds like bindweed and Canada thistle they can grow up through soil feet with no problem I have news for you putting weat barrier at the bottom of your raised bed is not going to stop those plants they'll crawl up between the bed and the wheat barrier no matter how hard you staple that on there they're still going to find their way out putting wheat barrier in the bottom of bed also affects the way the water flows through the bed it's going to tend to trap it down there you're making a bog in the bottom of your raised bed that's not good for plant roots there is no good reason to put weed barrier in the bottom of a raised bed it's not going to stop the weeds and it causes water issues most of the weeds you'll get in a raised bed come from above the Wind Blows the seeds in from around the raised bed that's where the weeds come from put something at the bottom does you no good whatsoever a lot of people like putting cardboard and newspaper in the bottom again in part to keep those weeds from growing and to kill the grass but as I've already said a couple inches of soy will do that so that's not necessary a lot of people are going around talking about lasagna guarding which is more correctly called sheet mulching lasagna gardening does not improve soil very much that cardboard has no nutrient it does have some carbon and that helps a little bit but putting paper in the bottom of your bed doesn't really improve anything now if you have some go ahead and put it down there and get rid of it but don't make a big deal about putting paper down there it's not going to help your raised bed how about wire mesh which is also called hardware cloth now this may make some sense putting this at the bottom of a bed prevents rodents digging up through it things like mice rats and Chipmunks but it only works if the holes in that hardware cloth are small enough it has to be at least quar in in or smaller now does this keep rodents out of your garden maybe but probably not mice and rats have no problems crawling up things so they can crawl up the outside of your raised bed and get at your food now where it does make sense to put something at the bottom is if you're trying to keep groundhogs out they don't climb so much they're mostly trying to dig underneath so that will work it also makes sense if you're planning to cover the bed with mesh keep things out there so you have a top covering and a bottom covering and now you can make that pretty rodent proof and that makes sense how about drainage people are very concerned about the drainage of this soil so they like to put stones in the bottom for added drainage well that simply doesn't work when you have two layers of different kinds of material so soil up here and Stones down here water comes through the soil and stops it doesn't go into the gravel I know that's not very intuitive but that's how it works gravel at the bottom does not increase drainage the same goes for house plants that's why you never put gravel or anything in the bottom of pots your house plants it simply doesn't work for increasing drainage don't put it at the bottom of a raise bed it doesn't work there either so there you have it those are the things you might put right in the bottom of a bed now let's move up to the middle layer the problem here is that people build beds and then they go out and they price PR the soil and it's going to be really expensive to fill these beds not to mention all the work of hauling soil around so the get online they look for better options cheaper options and they find some and so we start throwing all kinds of stuff into the bed so we don't have to buy soil well let's look at a couple of these options a very popular option are logs or branches any kind of leftover wood so that's put in the bottom it does take up space so you need less soil most this wood starts decomposing and absorbs moisture so it kind of acts like a watering system for your plants but there's a fundamental problem with this wood has a very high carbon to nitrogen ratio what that means is that when microbes try to decompose it they need to find nitrogen somewhere else and that somewhere else is in the soil around the wood the microbes pull nitrogen out of the soil to help decompose the wood but nitrogen is critical for plant growth so if plant roots grow down to where the wood is they're not going to find enough nitrogen the microbes are much more efficient at pulling that nitrogen away now you can compensate this by fertilizing more and adding more nitrogen to your raised beds you really don't have any idea of how much you should add over time this wood does decompose now big logs would take longer to completely decompose and smaller ones are faster but eventually all this wood decomposes as it decomposes the love of your soil falls down so let's say takes 10 years for the wood to completely decompose over that 10e period you're constantly having to add more soil to keep the level up after 10 years you filled the bed with soil so what was the purpose of adding this wood I mean it seems to me as if this is a short-term fix so you don't have to buy so much soil today but eventually you're going to have to buy that soil so why don't you just bite the bullet and buy the soil now get the job finished then 10 years from now you don't have to redo it another common suggestion I see is putting dry leaves in the bottom now in Fall you've got lots of these leaves and you can fill up the whole bed with leaves if you like but this has the same problem as wood leaves have very high carbon to nitrogen ratios and the microbes that decompose the leaves will steal nitrogen from the soil and from your plant root eventually those leaves decompose and your soil level shrinks now the leaves do add some organic matter to the soil and will improve it a little bit but this isn't the best way to improve your soil it's better to have that organic matter mix throughout the soil layer so if you have excess leaves sure throw them in the bottom but I don't think it's a really good solution what about kitchen scraps or yard waste kitchen scraps have a fairly high amount of nitrogen so they won't pull nitrogen away from your plant so those are a good thing to add but who has enough kitchen scraps to make much of a difference in a deep bed the yard waste has more carbon in it so again it has the same problem as dry leaves but if you have it you want to get rid of it it's better down there than giving it to the city in a green Bend but it doesn't really add much value to the raised pad you're better off composting that material and composting the leaves and bringing that back mulching your raised bed with compost how about rocks now we talked about small rocks in the bottom for drainage and that doesn't work but what about Big Rocks well they actually work if I fill the bed with both rocks and soil so that soil surrounds the Rocks the Rocks take up space you need less soil the rocks are very stable so they're going to be there for million years so rocks in there do work provid that you keep them away from the top foot or so of the soil because you don't want to bang them when you're digging plants but if they're in the lower section and you have soil between them they will reduce the amount of soil you need and if you happen to have the Rocks laying around anyways there's no cost involve and some people go out to places like building sites and scr rocks there they're happy if you take the Rocks away because they're going to have to clean them up anyways before they put a lawn down all right that takes care of the middle layer now we're talking talking about the top layer the soil that's where the plants are going to grow now if you have very high beds I would recommend that you have at least 2 fet of soil if you want to put something in the bottom to take up space all right I understand you want to save some money but at least 2 fet of that should be soil why because plants need the soil to grow in that's where all the roots are going to be now in nature plant roots tend to grow horizontal they go out from the plant but in a raised bed we're trying to plant very close together and they can't go out past the edge of the raised bed so you'll find more of the roots going down and 2 feet is a good depth for plant root now there's a number of options for soil uh the first one is real soil and a really good option here is top soil so top soil is the material that's removed before we do construction we usually take the top 4 to 8 in of soil away and preserve that because that's where all the nutrients are that's where all the organic matter is that's really good soil so we take it away and then we do construction like we build a new home and then we bring a small amount of that back to put around the new house so we can plant grass so we have these stock piles of top soil and people who have that sell it to gardeners and so that's a really good soil another option is a product called triple mix now in Theory triple mix is 1/3 top soil 1/3 Pete Moss and 13 compost now I've looked at a lot of people sell triple Mex and none of them guarantee that that's what goes into it and I suspect the ratios vary quite a bit depending on the cost of material but in general triple mix is 1/3 soil and 2/3 organic matter and it's great soil it's fluffy it's great for root growth grows great plants it has one big downside remember that 2/3 organic matter that's going to decompose over the next 2 or 3 years and as it decomposes it shrinks in size and the level of your soil starts dropping in the raised bed so each year you got to add some more soil to bring it back up then the organic matter decomposes the level goes down next year you buy some more soil you put it on top that happens a lot less with tops on now it settles a bit too because they tend to fluff it up before they deliver it cuz they're selling it in volume so it will settle that first year but after the first year it stays there it doesn't keep getting smaller and smaller but tripom does grow great plants now if you're buying either of those options buy it in bulk don't buy it in bag get several yards delivered to you now how do you know how much soil you need well if you're not great at math come over to garden.com and look up soil calculator there's an automation it calculator system you just enter the size of your beds and it tells you how much bulk material you'll need or how many bags you need and it works in both metric and imperial units a really great system you'll know exactly how much soil to buy a very common amendment is perlite or vermiculite now these materials are fairly similar to one another in the way they behave in soil they add paracity they they make the soil fluffier add more air in the soil and let water drain better they also hold water so they improve the quality of the soil now they don't add any nutrients both of these products are used in potting media that's used for house plants but I wouldn't use them outside both of these are man-made they're nonorganic so they don't decompose over time once they're in your soil you're stuck with them you there is no way to get them out if you decide you want them vermiculite in particular breaks down over time into smaller and smaller particles now it doesn't decompose but it does make these small particles which can cause problems in the soil I would just keep those out of the garden there's no purpose in adding those to raised beds what about compost and manure well these are excellent products and I've talked about them in many videos I love this stuff it's organic it decomposes over time it releases nutrients for plants it improves the structure of soil it's just great stuff so it's a good thing to add to soil and raised beds there is one downside because gardeners understand that it's good they use way too much if you add too much organic material to soil you can get to a point where you have high phosphate level and high phosphate is toxic to plants this problem has now been reported by a lot of people with raised beds and the reason is that they've just added too much when you're making a new raised bed and you're using soil and you want to add 20 to 30% compost manure that's okay and then in future years you just put a couple inches on the top as a mulch but don't use too much or you won't be able to grow anything in your bed there's a myth floating around that you can't grow good food in regular soil regular garden soil I don't know where this started but it doesn't make any sense all the farmers are using using regular soil my whole life I've been growing vegetables and garden soil now it's not always the best type of soil you might need to amend it and may improve it over time but it all grows great vegetable I think this is one of the reasons a lot of people have moved to race beds because they think that the soil in the ground can't be used which is a real shame because that's the easiest way to grow vegetable I also think it's one of the reasons that a lot of people with raised beds are looking for a another alternative other than soil so some people use a soilless Mex and one of the most popular is Mel's Mex uh this was developed by a gentleman by the name of Mel Bartholomew and he's the fellow who made square foot gardening popular wrote several books on it his favorite mix is oneir vermiculite oneir compost and one3 Peete Moss notice that there's no soil in there it's completely soiless now this makes a really nice soil it's really fluffy and Airy Roots just love growing into it so it is good for growing plants but it has a number of downsides I've already mentioned the problem with vermiculite the other two components are Pete Moss and compost and both of those are going to decompose over time so after a number of years you're only left with the vermiculite and a small amount of organic material you have to keep topping these up over and over and over again every year because they settle so much these soiless mixes also tend to dry faster and once that pea Moss is completely dry it's hard to wet now the vermiculite will mitigate that to some extent but the real problem with this mix is that it's really expensive compared to soil personally I wouldn't use it in a raised vet all right what would I use well I looked at all the combinations and all the recommendations and I want to find the best soil for rais bats and this is my criteria I want it to be reasonably priced hold moisture well grow great plants and have a material that doesn't shrink too fast I don't want to have to replace it every year here's what I think is the best soil for raised beds 75% top soil and 25% compost if the top soil is really sandy you might adjust that a little bit and do 70% soil and 30% compost that will add more nutrients and water water holding capacity to that Sandy mix but I think this the best soil top soil doesn't shrink very much we've added some organic matter that improves the nutrient level the clay in that soil will hold water better than any of the soiless mixes and I know for a fact that this grows great plants cuz I've used it myself what about filling the bed well I put nothing at the bottom except maybe hardware cloth if you're concerned about the rodents but I think in most cases they're not not that big of an issue so you can skip that step as far as the middle layer goes don't put anything in there whatever you put in there is just a temporary solution bite the bullet and fill the whole thing with soil at the very least you want 2 fet of soil in your raised bed if you've made really high beds and you can't afford the soil I strongly recommend changing the beds so they're not so high now let's look at some mistakes people make I seen a suggestion that you should use two different kinds of soil so they were using Jeep garden soil in the bottom layer and then on top of that they used a different soil like a triple mix soil or a soilless mix that way the cost is lower but that's a really dumb idea whenever you layer different kinds of soil on top of one another there's the potential of creating a perched water table that's a layer that doesn't allow water to move from one soil to the next don't do that if you want to use those two types of soil mix them all together before you fill the raised bed never have two layers of soil the second mistake is raised beds that are too high now I know some people have disabilities and they need the higher bed but listening to people online it becomes clear that many people are afraid to actually bend over and plant a few seeds they want the comfort of a raised bed well I have news for you if you do gardening properly you don't have to bend over very much sure you have to bend over to plant the seeds in the spring most of the weeds are taken care of by The Mulch you use taller plants like tomatoes and so on they're harvested high up anyways you don't have to bend over to harvest those one summer I actually measured how much time I actually spend bent over in my garden and it was very very small we're talking minutes to plant aural crops to harvest them go with a lower bed in fact I'd recommend using a raised bed that's no more than 8 in tall that will grow grow great food and solves all this problem of getting a lot of extra soil mistake number three people are afraid that their wood beds are going to rot so they put plastic between the wood and the soil and that seems to kind of make sense right you keep the wet soil away from the wood and that will reduce the amount of rot you get in the wood and your race beds last longer Unfortunately that logic doesn't work what the plastic actually does is that it traps moisture against the wood it doesn't allow it to seep into the soil or go into the air plastic lined raised beds actually rot faster than the ones without plastic so don't put anything between the soil and the wood mistake number four creating a bathtub now what do I mean by that well we built the bed we've set it on our lawn we' filled it with soil now if we look at this we actually have two layers of soil don't we we have the soil that's in the razor bad and we have our native soil which is below the raised bad those are two different kinds of soil so we can create this perched water table right at the bottom of the raised bed so water goes into the raised bed and gets trapped there and the bottom layer stays extra wet the solution to this is to put down your raised bed mark the area and then dig up that soil down about 6 in or so then put some of your fill soil into that and mix it up really well then add another 6 in of fill soil and mix that in the top layer so what we're doing is we're creating a transition we're going from native soil to partial native soil to even less native soil until we finally get into the fill soil when we have this gradual change in soil you won't create a water problem now let's have a look at some frequently Asked question do you need to kill the grass under the raised bed and the answer is no couple inches of soil will do that for you now if you're planning to dig up that soil under the bed then it might be a good idea to get rid of the grass but if you're not going to bother with that just put the raised bed right on the grass and it'll be dead in no time how full should you make this raised bed well I would fill it right up to the top and in fact I would overfill it a little bit and the reason for that is no matter what you're using it's going to settle a little bit even top soil settles the Act of bringing it to you the act of shoveling it putting it in the wheelbarrow shoveling it into the Raaz bad all of that adds air and fluffs it up so it's all going to settle so fill it as much as possible and a couple weeks ago will have settled and you can use it the final level you're heading for is about an inch or two below the rim of the raised bed that keeps the soil in allows some room for mulch and when you're watering the water tends not to run over the top of the race bed another common question is how much soil do I need and I've created a really nice soil calculator for you head on over to my website gus.com and search for soil calculator it's easy to use calculates everything automatically it'll tell you exactly what you need to get both in bulk material and bagged material I hope you enjoyed this video and now you've got your rais beds all full it's time to grow some vegetables if it's early in the season then you're thinking of starting things from seed have a look at this video here my 10 tricks for starting seeds and if you want to learn more about growing vegetables have a look this video here it covers my 10 favorite vegetables and how to grow them happy gardening

Channel: Garden Fundamentals

Views: 75,163

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Id: KT5GRK5y9NM

Length: 24min 42sec (1482 seconds)

Published: Mon Mar 18 2024