Cinderblocks are not toxic unless they maybe have been colored with something. If they are the grey cement color, I would think they are perfectly safe.
When planting strawberries in blocks filled with soil, I have found that they have to have extreame amounts of watering. Cinderblocks absorb heat, heat dries the soil.

I just attended a workshop here in my area and the instructor is a master gardener. The workshop was regarding drip irrigation but he was showing slides of his set up and he had raised beds using cinder blocks...get this though...He filled the holes in the cinderblocks with soil and used that area for a growing space as well.

Hey ya'll,
I have a small vegetable garden in between our
two garages. It's about 15x15. It is a raised
garden bed using cinder blocks as the border.
I have planted flowers in the openings and
they do well but do require regular waterings.
I tried a few herbs in them but they didn't
do well. I think it just got to hot here
and they just didn't get enough water. The
flowers seem to be a little more heat tolerant.
If given the choice I would use them again
I'll try to post some updated pictures on
my webpage and let ya'll know when I do.
Good luck with your gardens.

Brenda
South Louisiana

I tried growing things in those holes, but the concrete sucked out the moisture faster than the plants could.

Concrete is pretty stable, although fresh ones tend to be alkaline. If you plant acid-loving plants in/near them, the alkalinity may "offend" the plants. You can leach much of the alkalinity out by soaking, or by leaving outdoors in the rain all winter. Some people soak plantable concrete in water to which they've added some baking soda to neutralize the alkali.

Sue

If they are plain cinder blocks then no. If they have been painted or coated then maybe, depending on what they were coated with.

Here is a link that might be useful: Win $50.00 Of Free Seeds!

belgianpup,
Baking soda is alkaline. Try it for heartburn relief, it works great.

I've had good success planting small crops in the gaps of cinder-blocks, although you do have to keep up with the watering. I think that filling the gaps with dirt & planting into it actually helps to insulate the raised bed a bit, as well, and it looks pretty.

I've successfully grown radishes, marigolds and (surprisingly) basil in the gaps of cinder-blocks- it's actually my favourite way to grow radishes, because it makes for really easy succession sowing- just work my way around the border a few squares at a time, then do the next ones 2 weeks later, then the next ones, and by the time I finish filling the whole border with radishes the first crop is ready. And I can usually get 2 or 3 "french breakfast" radishes per gap.

Here is a link that might be useful: My previous veggie patch, with crops in the cinder-block gaps

Well, hatchjon, I guess those people over at the hypertufa forum don't know what they're talking about!

Okay, forget the baking soda, just soak them. Those cheap wading pools for kids are great. And they make a good drinking bowl/foot cooler for the dogs!

Sue

"...I guess those people over at the hypertufa forum don't know what they're talking about!"

Huh? Do they think baking soda is acidic????

Jim

Maybe they meant washing soda, rather than baking soda? I know washing soda (sodium carbonate) is slightly acidic. Or maybe a small amount of baking soda added to the water helps draw the lime out of the cinder block somehow?
I'm no chemist, so I don't know how/whether that would work; I wouldn't think you'd use baking soda to neutralize an alkali, though.
Although... I have heard that baking soda can be used (somehow) to give concrete an "aged" look.
--Amy

Baking soda has some buffering capacity. It can neutralize both acids and strong bases (alkalis). I wouldn't recommend it for soaking cinder blocks for the garden, though. It's pH in water is alkaline, and there may be a sodium issue for some people. I would check on the washing soda before applying it, too.

I've been considering lining the sides of some concrete block beds, to prevent moisture loss through the blocks. This would also block leaching of cement residues into the soil.

>Baking soda has some buffering capacity.

Praise be... Finally, someone other understands "buffering".

Something I can relate to! Three years ago, my now departed grandfather and I had raised beds composed of cinder blocks. They were 4' wide by 30' long by 3' deep. Stuff grew like gangbusters. As to not waste the space, we also planted bell peppers in every third hole in the blocks themselves, and they grew great. I totally concur w. Slashy though. Stick w. the small crops. I wouldnt, for example, try to grow a zucchini in there :-D

I'm planning a two-tiered cinder block garden with hole plantings in addition to separate container plantings for my central FL garden this year. I prefer to plant seedlings that I've started and will be using purchased soil. I plan to line the holes on the vertical sides with heavy leaf bag plastic to retain moisture and alleviate chemical leaching. Also planting plants within the bed that will drape over the block to help with heat as well, I hope. I've always had great success with newspaper (black ink only) and cardboard topped with grass clippings and/or pine needles as mulch. This year I will also be planting lettuces and such in the bed as "mulch." The essential to gardening here in FL conditions is definitely water and even partial shade for what is otherwise full sun plantings in other areas of the country. Proper interplanting for both shade, general compatibility and insect discouragement is not only essential, but provides a far more beautiful and interesting garden. Cut and come back harvesting ensures a prolonged harvest without successive plantings for many varieties as well, especially great for an almost year long harvest here in this climate. I'll post updates throughout the summer, but also welcome any and all comments.

Hi Lmaoingeneral ,
You may be overthinking this whole process, you sound like you are on the right track though, but , hopefully I can save you a few steps,
1. You don't need any plastic
2. Planting with "shading" in mind is good, just make sure there isn't too much shade, most everything really likes full sun, even if they aren't fond of heat.

You are going to do great...blessings....Jon

{{gwi:44923}}

{{gwi:23538}}

{{gwi:44924}}

{{gwi:19114}}

{{gwi:44925}}

{{gwi:15885}}

{{gwi:8599}}

{{gwi:12770}}

now there's what I call raised beds
How beautiful, I am envious

Jon
Can you please tell me how wide your beds are? I couldn't count the blocks to determine the width of your beds.
Thanks in advance.
Alberta

Hi Alberta,
4' wide ;-)

thanks Jon, thats what I was aiming for too, but the cinder blocks here only come in 18 inch lengths, so we had to go smaller. :(

Hi Alberta,
I got your email, all cinder blocks are 16" x 8" x 8" tall
my beds are measured from inside dimensions, so ...yes they are 64" total width , but I use the block holes to plant in also, so ...no loss of space, because they are two feet tall, there isn't an issue with being so deep, but if they were "ground beds" (where you have to bend over), I would make them narrower too......three blocks wide would give you a 32" planting bed .
{{gwi:44928}}

{{gwi:44930}}

{{gwi:8597}}

Here is a link that might be useful: building cinderblock beds (see all nine)