raised beds - how deep of soil needed?

[brianmanahan]

so i made some raised beds out of an old barrel, cut into 3 sections from top to bottom. each was about 6-8 inches deep, and i raised them to a few feet off the ground (setting on a frame made of 2x4s).

i planted strawberries in them, but they didnt survive the cold ohio winter 🙁 unlike the ones in the ground which did.

does anyone know how deep soil has to be in raised beds in order to make the plants not die?

 

[UglyCasanova]

I made one out of 2 x 4's that worked really well. It was 2 boards tall so 8 inches? And I filled it with soil may 3/4 of the way. Most of what I grew has died due to the cold, but I have a nice Rosemary bush growing. I had basil, tomatoes, sage, mint, and cucumbers growing and they all did really well this summer.

 

[T9D]

Well they need to be able to hold in heat. The ground stays a pretty even 50 degrees, slowly it freezes in winter. But even when it's freezing outside the ground will be warm for a long time. Raised beds have no way to hold heat. It just freezes the first night you get cold weather.

The beds should be actually sitting on the ground. Otherwise it's not going to matter how much soil you use. It needs to be able to pull heat from the ground.

 

[Capt Caveman]

Depend on the vegetable plants you'll be planting. Most plants will need 8-12" and tomatoes 20"+ but something like strawberries can probably get away with 6".

 

[bbhaag]

The freeze and thaw is what does the most damage in raised beds. The roots just can't handle it. What zone are you in?
Off the the top of my head 18-24 inches minimum and that's just depth. The overall square footage plays a factor too.

 

[GLeeM]

so i made some raised beds out of an old barrel, cut into 3 sections from top to bottom. each was about 6-8 inches deep, and i raised them to a few feet off the ground (setting on a frame made of 2x4s).

Those are not raised beds, they are more like a big flower pot.

It would be a raised bed if you put the section of barrel on top of prepared soil and then filled it with six inches more of soil.
The purpose of a raised bed can be:
to increase heat for plants that would do better in a warmer zone
to help with drainage if in low area
to not waste soil additives on non-growing areas
to help loosen soil for better carrots, etc.
they can look nice
etc.

cold ohio winter

LOL zone 5 or 6 probably? I have trouble keeping zone 3 plants alive through my winters!

 

[turtile]

It's because your raised beds are like pots. Therefore, they don't get the benefit of ground heat. You need to make very wide raised beds and insulate the surface with some type of mulch (6 inches at least). Plant roots and underground stems are much less resistant to cold and quick changes in weather. Freezing and thawing, like already mentioned, causes cells to explode since moisture is pulled out of the cell, freezes... repeat.

 

[Naer]

2 3rd deep

 

[Carson Dyle]

It's because your raised beds are like pots. Therefore, they don't get the benefit of ground heat.

This.

I'd call them "planters", at best. They're not raised beds.