Ideas for boosting the soil temp in raised beds

bigbubbacain · February 25, 2010

I never had to consider this before, but my plants are getting tall and leggy and i really need to do something soon. I have 2 raised beds, 6'x26' and I use drip irrigation. I've read old posts about plastic sheeting, newspaper, black mulch fabric, even the 3' rolls of that brown painters paper they sell at that "depot" place. Are any of these really going to contribute to raising my soil temperature?

kath · February 25, 2010

I've not measured the differences, but have had a lot of luck using clear plastic to raise soil temps both by laying it down over large areas to heat things up and by putting it over hoops in a row or bed to heat the soil and then provide a nice microclimate until air temps are more favorable. If you have sun, a raised bed should heat up quickly this way and be ready to accept and protect your transplants. The opaque materials i've only used to control weeds, and have only heard about black plastic being able to raise soil temp although less than clear plastic would.

Zana · February 25, 2010

If you place the clear plastic flat on the ground you run the risk of solarizing all the nutrients out of the soil. Not good, if you amended in the fall when you cleaned up the garden. Creating the raised hoop as Kath mentioned is like having a mini greenhouse. The soil will warm up, and will create a microclimate inside.

I used to have 2x4 extensions from the corners of my raised beds that I could staple clear plastic to in the spring and the fall. They were about 3ft high in the spring and I enclosed the sides and top with the heavy clear plastic. I was able to flip up the ends for cross ventilation if it got too hot, and tape the corners closed if it was too chilly. This worked for warming up the soil and also hardening off the plants. (They were about 10ft high total in the fall to accommodate the higher plants. A bit of a pain in the arse to enclose from a ladder. But I was usually still harvesting until we got snow - whenever that was.) I later started taking the top 6-8" of the "soil" from the raised beds and putting it in wheeled garbage bins that were placed inside the insulated garage over the winter. The "soil" wasn't put back into the beds until right before I set up the plastic. I usually gave it about a week more before planting out. But had no issues.

I didn't find the various papers helped much. They usually broke down if they got wet. The black plastic heated up and killed the weeds, but also killed pretty much anything else good in the soil if placed right over the soil. These are just my experiences...but I'm no expert. My raised beds are "portable" now. And all their "soil" are in the wheelable garbage bins, so I'll probably not look at setting them up until May, if I'm allowed to do so.

Good luck.

bigbubbacain · February 25, 2010

Thanks Kath and Zana!

I do like that "hoop" idea. Mine is going to require a lot of thought because I do my growing on 6'x15' stock panels mounted to 7' metal T-posts. I suppose I'll need to take the panels down or go all the way over them.

Blueaussi · February 25, 2010

Consider this:

http://westsidegardener.com/howto/hoophouse.html

Works for me to extend my season, and it goes up and down pretty easily. It's also easy to alter the lenght is you don't need it to be 21 feet long.

BR · February 26, 2010

I've made similar hoop houses to extend the season here in Oklahoma. Overall... it was not worth the effort in my area. High winds destroyed the plastic, but even worse was the fact that shorter days and cool temps shut down the ripening process so I ended up picking them green anyway. Mother nature won the battle. I had a bumper crop of green Brandy Boys so I made lots of Fish House Green Tomato Relish. I now use much smaller hoop houses for early season cold snap protection and that is working great.

Blueaussi · February 26, 2010

By the time I put up a hoop house in the fall, most of my tomatoes are already gone. I overwintered mostly peppers and egg plants, plus a few ornamentals and herbs in my hoop house. I picked ripe egg plants and peppers up through Christmas, and then the short days and cool temperatures shut down fruit production.

I still had to use heaters on nights that got into the low twenties, and that gets expensive fast, so I only use one to extend the season a bit now. It was nice to have large pepper plants and egg plants ripening fruit in March, though. And to have all the space I needed when I started hardening off seedlings.

BR · February 26, 2010

Sorry... I guess I shouldn't have assumed we were talking about tomatoes.

bigbubbacain · February 26, 2010

Quote:

Originally Posted by BR

Sorry... I guess I shouldn't have assumed we were talking about tomatoes.

BR, it's all relevant. pepper and eggplant are also in the nightshade family.

Anyway, I'd lean towards hoophouses if I thought I'd need them until April. I'm just looking for something quick & dirty that I can put into action this weekend.

bigbubbacain · February 26, 2010

Blueaussi, I sent you a private message. Please get back to me.

Bubba

dice · February 26, 2010

Alfalfa meal mixed/tilled into the top 6 inches of soil would
help. Kind of expensive to get that much of it, though, if
you don't grow it yourself. (Bales have a lot of stems along
with the green leafy matter. I don't know if they will heat
up the soil the same way.) Fresh grass clippings might work,
too.

(I am extrapolating from gimme3's post about shredding his
crimson clover winter cover crop and shallowly mixing it in
a couple of weeks before transplant to heat up the top
6 inches of soil for lettuce and similar. Vetch would be good
for that, too, as the top growth decays quickly.)

bohica · February 26, 2010

I've used similar hoop houses for years, the only difference is that I use 2 ft rebar to hold the PVC in place and we do not secure the plastic to anything, we hold it down with 2 x 8 walking boards, this way if we need to cool the hoop down fast, we just remove the boards and lift the plastic, I use snap clamps or wire clamps to secure the plastic to the pvc.

February 25, 2010	#1
bigbubbacain Tomatovillian™ Join Date: Apr 2007 Location: Zone 9 Texas, Fort Bend County Posts: 436	Ideas for boosting the soil temp in raised beds I never had to consider this before, but my plants are getting tall and leggy and i really need to do something soon. I have 2 raised beds, 6'x26' and I use drip irrigation. I've read old posts about plastic sheeting, newspaper, black mulch fabric, even the 3' rolls of that brown painters paper they sell at that "depot" place. Are any of these really going to contribute to raising my soil temperature?

February 26, 2010	#11
dice Tomatovillian™ Join Date: Jan 2007 Location: PNW Posts: 4,743	Alfalfa meal mixed/tilled into the top 6 inches of soil would help. Kind of expensive to get that much of it, though, if you don't grow it yourself. (Bales have a lot of stems along with the green leafy matter. I don't know if they will heat up the soil the same way.) Fresh grass clippings might work, too. (I am extrapolating from gimme3's post about shredding his crimson clover winter cover crop and shallowly mixing it in a couple of weeks before transplant to heat up the top 6 inches of soil for lettuce and similar. Vetch would be good for that, too, as the top growth decays quickly.) __________________ -- alias

February 25, 2010	#2
kath Tomatovillian™ Join Date: Jan 2010 Location: zone 6b, PA Posts: 5,664	I've not measured the differences, but have had a lot of luck using clear plastic to raise soil temps both by laying it down over large areas to heat things up and by putting it over hoops in a row or bed to heat the soil and then provide a nice microclimate until air temps are more favorable. If you have sun, a raised bed should heat up quickly this way and be ready to accept and protect your transplants. The opaque materials i've only used to control weeds, and have only heard about black plastic being able to raise soil temp although less than clear plastic would.

February 25, 2010	#3
Zana Tomatovillian™ Join Date: Jan 2007 Location: Southwestern Ontario, Canada Posts: 4,521	If you place the clear plastic flat on the ground you run the risk of solarizing all the nutrients out of the soil. Not good, if you amended in the fall when you cleaned up the garden. Creating the raised hoop as Kath mentioned is like having a mini greenhouse. The soil will warm up, and will create a microclimate inside. I used to have 2x4 extensions from the corners of my raised beds that I could staple clear plastic to in the spring and the fall. They were about 3ft high in the spring and I enclosed the sides and top with the heavy clear plastic. I was able to flip up the ends for cross ventilation if it got too hot, and tape the corners closed if it was too chilly. This worked for warming up the soil and also hardening off the plants. (They were about 10ft high total in the fall to accommodate the higher plants. A bit of a pain in the arse to enclose from a ladder. But I was usually still harvesting until we got snow - whenever that was.) I later started taking the top 6-8" of the "soil" from the raised beds and putting it in wheeled garbage bins that were placed inside the insulated garage over the winter. The "soil" wasn't put back into the beds until right before I set up the plastic. I usually gave it about a week more before planting out. But had no issues. I didn't find the various papers helped much. They usually broke down if they got wet. The black plastic heated up and killed the weeds, but also killed pretty much anything else good in the soil if placed right over the soil. These are just my experiences...but I'm no expert. My raised beds are "portable" now. And all their "soil" are in the wheelable garbage bins, so I'll probably not look at setting them up until May, if I'm allowed to do so. Good luck.

February 25, 2010	#5
Blueaussi Tomatovillian™ Join Date: Apr 2009 Location: South Carolina Zone 8a Posts: 1,205	Consider this: http://westsidegardener.com/howto/hoophouse.html Works for me to extend my season, and it goes up and down pretty easily. It's also easy to alter the lenght is you don't need it to be 21 feet long.

February 26, 2010	#6
BR Tomatovillian™ Join Date: May 2006 Location: Oklahoma Posts: 71	I've made similar hoop houses to extend the season here in Oklahoma. Overall... it was not worth the effort in my area. High winds destroyed the plastic, but even worse was the fact that shorter days and cool temps shut down the ripening process so I ended up picking them green anyway. Mother nature won the battle. I had a bumper crop of green Brandy Boys so I made lots of Fish House Green Tomato Relish. I now use much smaller hoop houses for early season cold snap protection and that is working great.

February 26, 2010	#12
bohica Tomatovillian™ Join Date: Jul 2009 Location: NY Posts: 113	I've used similar hoop houses for years, the only difference is that I use 2 ft rebar to hold the PVC in place and we do not secure the plastic to anything, we hold it down with 2 x 8 walking boards, this way if we need to cool the hoop down fast, we just remove the boards and lift the plastic, I use snap clamps or wire clamps to secure the plastic to the pvc.