You have chosen to garden in raised beds. The frames are set and it is time to fill them with fertile soil that will serve as a good growing medium for your garden plants.
One option is to buy a good grade of commercial soil, but that can easily break the bank. The best solution is to make your own.
You night want to start by taking a soil sample from the garden. Have it tested at a reputable laboratory. It is best to choose one close to your location. The test results can help determine what you need to add to the soil to improve it. Fertile, well-drained soil will provide a much better growing medium than that of tightly compacted dirt that lacks nutrients.
Fertile Soil Recipe
What constitutes fertile, healthy soil? It includes a mixture of minerals, organic matter, air and water. The organic matter can be either plant or animal material such as manure that has gone through the composting process. It is called humus when completely decomposed.
The ideal soil sample has a granular, crumbly structure that provides good drainage. The loose soil will also allow oxygen and carbon dioxide to flow freely within the dirt.
A basic recipe for making your own soil is to use equal volumes of peat moss, coarse vermiculite and compost. A garden bed that is 4-feet by 4-feet square will need eight cubic feet of the mixture. This mixture will be high in nutrients and should promote good plant growth. The compost helps keep the soil loose. The vermiculite and peat moss help retain water.
Adding Organic Matter for Rich, Fertile Soil
If for some reason you cannot make your own soil, add organic matter to your dirt to promote fertility. Organic matter such as composted plant and animal products such as manure helps the soil retain nutrients that the garden plants need to grow. Adding organic matter to sandy soil aids in water retention. Adding organic matter to clay soil helps to loosen the dirt.
Adding mulch to the raised garden beds is another means of adding organic matter. However, you may not realize the benefits (other than helping to eliminate weeds) right away, but the mulch will break down over time and serve as a good source of additional organic matter.
Making your own compost is easy to do and it helps keep vegetable, fruit and yard waste out of our landfills. It can be as simple as collecting the trash bags your neighbors fill with leaves. Poke a few holes in the bags close to the top and bottom. This allows oxygen and water to enter the bags and allows carbon dioxide and excess water to escape. Add a shovel of garden soil to the bags. Add a little water to the bags. Mix by rolling the bag on the ground. It is a good idea to roll the bags every few weeks. Voila. Come spring, you’ll have a source of fertile nutrients you can add to your raised garden beds.
Want more information about raised bed gardening?
Read Cornell Cooperative Extension’s guide to raised bed gardening.
This Gardening in Small Spaces article from the University of Kentucky’s Cooperative Extension Program is a good source of information for those who garden in small areas.
Visit the NRCS website to learn how worms can help keep your garden soil fertile.
Visit Organic Gardening Magazine’s website for information on making your own compost.
You say a 4 ft x 4 ft garden bed needs 8 cubic feet of soil. But you didn’t mention how much depth that gives you. Depending on if you want, say, a 12″ high bed or want a 24″ high bed, the soil amounts needed are obviously very different. Just thought that was important to mention to any beginners out there. Or those that are mathematically challenged. =)
Just do the simple math:
4 ft x 4 ft bed is 16 Sq. ft.
8 cubic feet of soil / 16 sq. ft area = 1/2 ft. or 6″ of depth.
If you do common core math, no telling what answer you will get!
One question I have is that all the pictures I see for making and setting frames for raised beds show them sitting on top of grass. What do you do to keep the grass or weeds from the ground you placed the frame on from coming through. Does adding all that dirt keep this from happening or do you have to dig up the grass or treat it before you add soil. I am new at this so don’t laugh.
@Colleen
That’s a very good question. You need to put down weed barrier / landscaping fabric over the grass, and then put the dirt for the raised bed on top of that. You can also use about a 1/2 layer of cardboard to cover up the grass. You’ll ideally want to put the cardboard all the way where it goes a little bit outside of the raised bed so that you don’t have the grass coming up through the edges. After a few weeks, you can water the cardboard around the edges and cut it away.
If you are just starting the beds now use a layer of newspaper. If you start in the fall use a layer of cardboard. You might want to use a garden broadfork to loosen the soil without disturbing the existing layers of soil.
I’ve used both landscaping cloth and cardboard to line the bed before putting in soil. Eventually the cardboard composted itself and not weeds but tiny capillary roots from a maple tree about 20 feet away invaded my nice soil mix. I’m sure the landscape cloth will rot eventually, but I wasn’t expecting roots!
Dear Sir,
In our house, back side , is one groundhog, it has made lot of big holes under the shed and under garage floor.Would like to get rid of it. He also eats all greens -(when we plant.)
Also dear comes around the house at night, how to keep them away.Not able to grow anything in the garden.
Thank you for free update garden minute.I was looking for such information for long time.
Ruth
I moved to Bloomington,Il from central Maine and longed for my garden. We live in a subdivision with eighteen feet between houses. My son made me two four by eight raised beds, end to end with four feet between, which he added a triangle with fencing for our cukes. we bought compost from a college farm and I do not need to tell you the wonderful vegtables we raised. The great thing is it is “spreading” to other nieghbors. We have had people ask for a tomato for their salad or an onion . Grami Cheryl
Dont laugh and I know we live in the country but we put sticks with tin pie pans tied to them in our garden to keep deer out. They dont like the noise or the shine. Also my husband relieves himself around the edges. I know sounds crazy but we dont have deer eating our garden either.
i have abed 4ft x37ft x8inc deep empt what do i fill it up with and whin
I have the 2 box spring frames from our old King sz bed. It’s just a wooden frame with fabric over it. Can I just flip these over and make 2 raised beds in them? The fabric covering could act as the weed barer.
Intetested in hearing your thoughts. Celene
Mattresses and boxsprings are treated with SO many chemicals to keep them fire retardant. The wood is treated as well. I would def not use them to grow veggies. Pitch them and if cost is a factor buy or recycle some cinder blocks as a boarder. They are pretty cheap then use the cardboard trick for the weeds.
Peat moss – A sustainable resource?http://www.organicgardening.com/learn-and-grow/questioning-peat-moss?page=0,1
That is a good point. You can substitute coir (made from coconut husks) for peat, and it will turn out the same.
Your recipe for make your own soil is actually a “soil-less” recipe. Why no soil which I thought was micro nutrients and other beneficial stuff?
I have used the describd ‘Mel’s’ mix in seveal beds and it is a great mix.
it sometimes is hard to come by vermiculite at an accepatble price and I have also experimented with coarse sand. of the kind that is used to lay pavements on. It gives good drainage and performs well if you just do 1/3 peat 1/3 compost 1/3 sand.
In all honesty… I don’t use peat moss but cocofibre. More sustainable and just as good
I have two of my own risebad garden on my office. I was made it from a unused banner. I still confused to fill the risebad, is it oke if i use a rice peel, composed manure and garden soil and i mix them together ? How much should i use rice peel? Thankyou. I am new at this.
Same raised beds for 3 years, add compost and that’s it. Should I be adding something else?
I think you’re right. For an established garden, just amend the soil with compost. You might also want to rotate your crops, so you aren’t planting the same crop or family in the same spot every year. This helps replenish the nutrients in the soil, and should also slow down pests. They will look for your tomatoes, beans, squash, etc. where they were the year before.
I have 4 by 4 by 3 feet deep. Can I use horse poop in my old used soil that’s 3 yrs old. Is it to rich for tomatoes
Don’t use fresh manure. It needs to be composted or aged. The only exception I’ve heard is rabbit manure. That supposedly can be used fresh.
I have two very heavy wooden raised beds for gardening way off the ground. (Saving my back), but before I place the soil mixture in, do I need to line the wooden bed boards with something so the boards don’t rot from the rain or watering . Thank you.