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New raised bed, what kind of soil?


My name is Jack I am from Long Island, New York. I have constructed two 8' x 3' beds raised 2' tall. I am unsure what to fill my planters with. I intend to make them into vegetable gardens. I'm under the impression that I should line the bottom with a mechanical mesh and then a garden membrane. Then am I supposed to fill the lower like 12" with a basic soil to kind of fill space and for the last 10" use a compost/soil mix? Please advise!!

Thank you

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Re: New raised bed, what kind of soil?

I would buy bulk garden soil. Lots of companies can deliver it to you for a delivery fee. Or you could buy big bags of garden mix at a store.
And you can use manure which can be bought at a local gardens store for less than $5 for about 10 gallons!

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Re: New raised bed, what kind of soil?

I wouldn't put any "membrane" down. You don't even need the mesh and it keeps your plants from rooting down into the natural soil. But since your beds are two feet deep, that is probably OK. If you are trying to stop grass and weeds from coming back into your beds, just line them with cardboard. Wet the cardboard down thoroughly and then put your soil on top. The cardboard will smother the grass, but then it will break down and get out of the way.

You are right about the soil. The bottom part can be any decent topsoil (not too clay like or rocky). Then you want a good planting mix with mixed composts (from various sources), maybe some well aged composted manure, perhaps mix in some peat moss or coconut coir. You want your top layer to be pretty light and fluffy.

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Re: New raised bed, what kind of soil?

I agree with putting cardboard or wet newspaper down. It will kill all grass and weeds while still allowing for growing deeper into the native soil and provide access to the beneficial earthworms.

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Re: New raised bed, what kind of soil?

If you are trying to keep pest out you can put a wire screen at the bottom of the bed and put cardboard on top to that to block weeds. Make sure your bed gets at least 6 hours of full sun for veggies. If you are planning to plant something large like tomatoes, put them in 18 gallon or 20 inch pots instead and make a cage with concrete reinforcement wire. My cages are 7 ft tall by 6 ft long. Caging means you don't have to do as much pruning. 6 inch diam. CRW allows your hand to get through the wire to reach the fruit. If you put tomatoes in an 8x3 bed and you have a 7 foot trellis on the north side, you could probably get 4 tomatoes in there. If you use SFG spacing you can get 8 but you will be pruning off all of the side shoots and most of the fruit. Pots use potting soil, a 2 cu ft bag of MG will fill an 18 gallon pot 3/4 full. I use part of a second bag to fill it within a couple of inches from the top since potting soil settles. I add 1/2 cup of complete starter fertilizer and I supplement at flowering, first fruit, and monthly thereafter. You could add all of the fertilzer as a band about 4-6 inches down in the beginning. 2 cups citrus food plus micros or 3 cups organic. 8-8-8.

If you have a local composting facility and a truck. Check with them about getting a vegetable garden mix. Mine costs about $48 for a cubic yard if you pick it up yourself. Delivered it is $240. If you tell them the dimensions of the bed or you can do the math to figure out the volume of your bed. I would also make sure your bed is reinforced on the outside if you made it of wood to handle the weight of wet soil. If you made the bed with concrete tile and reinforced it with rebar and pack the cores with stones or soil, it will hold.

If you are building the garden now and plan to use it right away, you can make a lasagna bed, but you will have to top it with 4-6 inches of good garden soil or potting mix and fertilizer (with added nitrogen) to use it right away.

Otherwise Mel's Mix works
1/3 good garden topsoil
1/3 compost from multiple sources
1/3 vermiculite, perlite, coarse sand (builder's sand), or cinder for drainage.
Don't use cinder if you are going to grow root crops like carrots.

Blend it all together and fill the beds. You still need to add fertilizer. If you want to be organic your topsoil will have to have a lot of organic matter in it to get enough soil microbes. Bagged "topsoil" usually is just dirt. It is better if you can get soil that is loaded with organic matter like the first few inches of soil in a forest, or soil near bodies of fresh water or if you can get soil from the yard if it is rich in organic matter like someone's established garden. Even if you cannot get the volume, what you really want are the microbes in that soil to seed your bed. You can also add vermicast which has live organisms and use EM to stimulate growth. Over time as you add organic matter the soil community will build up and all you have to do is keep adding organic matter and fertilizer.

Organic in the first few years from a scratch bed is not going to yield as much as a bed fertilized with proper amounts of synthetics. Get the soil tested after it is blended to find out how much fertilizer you need to add. If you want to do it organically ask for organic recommendations.

I am not 100% organic, I add compost to feed the soil and to release bound phosphorus, but I do not like to use animal based fertilizers and unfortunately they are the best source of organic nitrogen. I do get soil tests and I only need nitrogen and sulfur to amend the alkaline beds. The best choice for me is sulfate of ammonia. My soil does not need phos, potassium or calcium for years. You can call your local master gardener and get information on getting a soil test. A soil test from my local university for basic pH and nutrients costs $25. I've saved more than that by not buying fertilizer I don't need and using less of the ones I do.

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Re: New raised bed, what kind of soil?

buy garden soil /manure/compost in bags at big stores Few years ago I bought garden soil in bulk delivered in dump truck but was a nightmare - full with weeds

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Re: New raised bed, what kind of soil?

That really depends on the quality of the "top soil" you got. If you are only going to need a small amount then buying in bags make sense. But it you need a lot, compost is cheaper bulk from the compost facility. If it is properly composted it should not have a lot of weed seeds. You can get manure free from stables, but it may contain weed seeds and fresh manures from chickens, cattle, pigs or horses are best put in the compost pile and hot composted first. I don't buy dirt. The compost I prefer to use is peat moss, but I only use it when I want to bring the pH in my garden back down again. It is expensive and not commercially sustainable. My plants do grow better in it as it is an organic compost and it retains water and improves soil tilt and cec, and it keeps pH more stable for a longer time than sulfur. Most of the pH issues were being maintained by the alkaline compost that is available at pH 7.8. It is also why I no longer use chicken manure.
I can grow tomatoes again, sort of, in my alkaline plots again although they grow much better in my garden with the pH 6.4. The only things that are happier in the alkaline plot are the root crops.
People worry too much about acidity. Most plants prefer a slightly acidic soil anyway and most plants that are not cacti, baby's breath, or native to dry, sandy and salty soils, can tolerate a pH of 5.5 and do fine. Most nutrients are still available in acidic conditions but become severely deficient in extremely alkaline conditions.

Peat moss has a pH of about 4 to 4.5. But it was until recently the main ingredient in soil potting mixes. When potting mixes started replacing peat moss with compost, the plants did a lot worse or just plain would not grow in some mixes that contained more than 20% compost. Planting in pure peat moss is not a good idea not so much because of the pH but because it can hold way to much water and not enough oxygen. It should always have drainage material like perlite or vermiculite, or be mixed with soil.

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Re: New raised bed, what kind of soil?

The $2 bags of topsoil, compost, manure, etc at the big box stores are mostly filler material and I do not recommend them.

Yes sometimes delivered soil can be full of weed seeds. If you can get it delivered a few weeks early and cover with black plastic it might kill the weed seeds.

A 3x8 bed will comfortably grow 6 indeterminate tomato plants grown in cages.

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