Oftentimes the biggest challenge with raised garden beds is filling them. You have to be extra careful what kind of compost, mulch, or soil you use as this will be the growing environment for your plants. If you are on a really tight budget then you can make a short raised garden bed as it is cheaper to fill it with high-quality compost and mulch. The next year just make the raised garden bed smaller and add more compost, soil, or mulch.
If you want to fill a raised garden bed for as cheap as possible then you have to use local materials that are readily available. You can use local deadwood as the base of the raised garden bed, then place local soil or soil from a nearby forest, and on top of it simply place a thick layer of mulch. If you have grass clippings or a lot of dead or decaying leaves in your area then you can use them as mulch for your raised garden bed.
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Before deciding with what to actually fill the raised garden bed you have to think about what kind of soil, compost, and mulch the plants you will be growing actually like. This way it will be a lot easier to control the soil PH, drainage, and the amount of nutrients the raised garden bed has. If you are relatively new to raised garden beds then there is simply no reason to fill it up with expensive soil and compost.
You should also think about why you want to use raised garden beds, either the local soil is too poor in nutrients, there are too many posts in the area like slugs, or simply because raised garden beds are easier to work with, especially if you are older. If you want to know what to put on the bottom of the raised garden bed then check out my recent article What To Put On Bottom Of Raised Garden Bed ( Top 12 Materials ).
Fill The Raised Garden Bed With Local Soil
By far one of the cheapest ways of filling a raised garden bed is to use local soil. Local soil is readily available, and it is free, although you will have to do some manual labor. Although local soil is the cheapest way of filling a raised garden bed it doesn’t mean that it is actually a good idea. If the local soil is relatively poor in nutrients then there is simply no point in making a raised garden bed with the same soil.
On the other hand, you could use around 30-50% of local soil for the raised garden bed and the rest should be compost and mulch. Make sure to break up the local soil as best as you can, especially if your local soil contains a lot of clay. If you want to know more about gardening in clay soil then check out my recent article Gardening In Clay Soil ( Top 7 Tips To Improve It ).
Fill The Raised Garden Bed With Forest Soil
If you want to fill the raised garden bed as cheaply as possible and with high-quality soil then you should definitely use forest soil. The soil in most forests is jam-packed with nutrients, organic matter, microorganisms, beneficial fungi, and bacteria. The trick is to only use the top layer of around 10 inches of the forest soil, especially if the local area tends to be clay soil. The dead leaves and rotting wood found in forests can be used as mulch in the raised garden bed. If you want to know how to break down clay soil then check out my recent article How To Break Down Clay Soil Fast ( In 8 Easy Steps ).
Fill The Raised Garden Bed With Logs
Filling the raised garden bed with logs is also called Hugelkultur, and it is extremely good for raised garden beds. The logs should be placed on the bottom of the raised garden bed and then covered with a layer of soil and mulch has to be placed on top of it. You can easily find dead or rotting wood in your local forest, just be careful what kind of wood you actually use as not all of them are good for Hugelkultur.
The thicker the logs are the slower they will break down, so if you just want to test out Hugelkultur with your raised garden bed then do it with smaller logs or twigs. If your local area has a termite problem and your house is also mostly made out of wood then I do not recommend this method.
Fill The Raised Garden Bed With Grass Clippings
If you have a well-maintained lawn then you can use the grass clippings to fill the raised garden beds. Just keep in mind that if you have used some pesticides, herbicides, or insecticides on your lawn that these will stunt the growth of the plants growing in the raised garden beds. On the other hand, if your lawn has not been treated chemically then you can use the grass clippings. This process of filling the raised garden bed is somewhat slower, but you will end up with great composted grass clippings around a year later.
Ideally, you should fill the raised garden beds with grass clippings, in such a way that the grass clippings are taller than the raised garden bed. This is extremely important as the grass clippings break down they will lose a lot of volume. Only use the raised garden bed for growing plants the next year.
Fill The Raised Garden By Making A Lasagna Garden
Lasagna garden refers to a gardening style that uses several layers of soil, compost, and mulches in the raised garden bed. You can make a Lasagna garden as simple or as complicated as you want, although my personal recommendation is to use what you have available locally. The most important part about a Lasagna garden is to make a thick layer of cardboard on the bottom of the raised garden to smother out weeds.
Fill The Raised Garden Bed With Compost
Filling the raised garden bed with compost is relatively cheap as long as you make your own compost. On the other hand, it can take a fairly long time to make enough compost to fill the raised garden beds. In this case, you could use store-bought compost and mix it in with your own compost. Keep in mind that making high-quality compost is a form of art, so if you are new to making compost then you should buy it instead of making it as a lot of things could go wrong.
Fill The Raised Garden Bed With Worm Castings
Worm castings are the poop of worms, you can either buy them in bulk or you can make them. Filling a raised garden bed with worm castings can get expensive, although this can be considered as an investment for future harvests. On the other hand, you can always make your own worm castings, as it is relatively simple, although the downside is that it can take a long time until you can make enough worm castings to fill your raised garden beds.
Fill The Raised Garden Bed With Animal Manure
Animal manure contains nutrients, microorganisms, and organic matter which most plants need to thrive. If you have the possibility to get animal manure in your local area then you should definitely use it for your raised garden beds. The manure from cows, chickens, ducks, sheep, and horses are usually the best for gardening. Make sure that the animal manure comes from an organic animal farm as the quality of the manure from these places is the best.
Fill The Raised Garden Bed With Mulch
You can actually grow plants directly in the mulch, this is called the Ruth Stout method. Ruth Stout was growing vegetables directly in her hay mulch, without having to dig or till the soil. For this method, you have to use mulches that break down relatively fast like, hay, straw, grass clippings, and leaves. Make sure to make a thick layer of mulch in the raised garden bed and use it as a growing environment for your seedlings.
Fill The Raised Garden Bed With Soil Mix
You can easily find different soil mixes at your local garden center, and if you want to get as much soil for as cheap as possible then you have to wait for a sale. Generally speaking at the end of the gardening season most garden centers will have massive sales. Get the soil on a sale and simply fill the raised garden beds with it, make sure to place a thick layer of mulch on top of it, and the next year you can use your raised garden beds.
Fill The Raised Garden Bed With Peat Moss
Filling the raised garden bed with peat moss can be relatively cheap if you live in an area where the peat moss is actually harvested. Peat moss tends to be somewhat acidic, so if you are planning to grow plants that favor acidic soil then peat moss will be excellent. On the other hand, peat moss harvesting tends to put a lot of strain on the local environment, so you should probably avoid it if you care about the environment.
Fill The Raised Garden Bed With Cover Crops
If you want a relatively hands-off approach to filling your raised garden beds then you should consider growing cover crops. As long as your raised garden beds are placed directly on the soil, you should be able to grow some cover cops. Once these cover crops are fully matured you can cut them down and let them decay. Cover crops like rye, oats, and crimson clover tend to grow relatively fast. In addition to this, you can also use nitrogen-fixing cover crops as these pull nitrogen out of the air into the soil.
Smaller Raised Garden Beds Are Easier To Fill
The smaller and shorter the raised garden bed is the less money it will cost to fill it. If you do not have enough money to fill an entire raised garden bed but you still want high-quality soil then you should fill it around 30-50%. Every year you should add more and more soil, organic matter, compost, and mulch on top of it. This way you do not have to sacrifice the quality of the soil, and you can grow plants in the raised garden bed as soon as possible.
As you can see there are a couple of extremely good ways for filling your raised garden beds either for free or for as cheap as possible. As long as you use local soil and mulches you should be able to cut down the costs of filling the raised garden bed significantly. On the other hand, if your local soil is relatively poor then you should definitely buy at least some of the soil for your raised garden beds.