Hoop house bed: plastic cover now, frost blanket later?

schastapopFebruary 29, 2012

I've built a "hoop house" bed and am planning on putting into it some warm season plants that I've started already (e.g. tomatoes, basil, squash etc.) This will not be the permanent home for these plants - they will still be in their small containers until it warms up enough to move them into their own beds.

1st question: is this a good plan? (i.e. keep the plants warm in this psuedo-greenhouse until it warms up and then plant them in other beds).

2nd question: Should I put a clear plastic cover over the bed now and switch out with the frost blanket later, or just go straight to the frost blanket right now? I'm not sure what I should be basing this decision on. The frost blanket is supposed to provide 4 deg of protection (or so says the package). Its just been so warm in the day lately that I don't want to overheat them with the plastic; but I'm also concerned about cold nights.

Once the warm season plant containers are moved out (and planted in other beds), I plan to plant squash, zucchini, and cucumbers in the bed and continue to use the frost blanket throughout the summer to hopefully keep squash bugs out.

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Okiedawn OK Zone 7

My answer to your questions hinges on the size of your hoop house. Is it a low tunnel that you cannot walk into, but rather just reach into or is a high tunnel more like a greenhouse than you can walk around inside?

And, are the plants still inside the house if that is where you've been raising them? Or, have they already been hardened off to outside winds and temperatures?

If you can provide the answers to those questions, I'll do my best to answer your questions.

As for growing the squash under the frost blanket, there will be somewhat less light reaching the plant and that can delay the ripening of the fruit. Also, unless you are growing parthenocarpic plants, you'll either have to hand-pollinate your squash plants, or uncover them once they are blooming to allow insect pollination. They sell a special weight of floating row cover for summertime use for insect protection and it is thinner and allows more light to reach the plants than the frost-weight row covers do. Finally, be sure you put the squash covered by floating row covers in an area that is well away from any place you've grown squash before because otherwise you may find squash bugs were overwintering in garden debris and have hatched out underneath your floating row cover.

    Bookmark   February 29, 2012 at 9:28PM
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Hi Okiedawn,
The bed is brand new (size 10'x4') and the hoops are a low tunnel. Currently the plants spend the night in the garage and the days out in the sun, but slightly shielded from wind.

Thanks for the info about the lighter-weight blankets... I'll check into those too. I was expecting to have to hand pollinate, but I hadn't done any research yet on what that actually involves - I am not expecting it to be a huge challenge.

    Bookmark   February 29, 2012 at 11:22PM
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Okiedawn OK Zone 7


You're welcome.

With a low tunnel, I'd probably put the frost blanket over it and leave it there as long as it allows enough light penetration. Then, if cold weather threatens, I'd add the layer of plastic on top of it, but I'd remove the plastic in the morning once the temps have warmed up above freezing. The problem with a plastic-covered low tunnel is that it will warm up incredibly hot and incredibly fast on a day like today when the highs are in the 70s or 80s.

I have a high tunnel greenhouse and, without open vents and shade cloth, it was over 100 degrees in there on sunny February days when the air temperatures were in the 20s or 30s at night and in the 50s through the 70s during the day. Before we put the shade cloth on the high tunnel, the temps were over 100 degrees in there every day. Now, with shade cloth and 4 open vents and 2 open doors, I can keep the high tunnel only a little warmer than the outside air temps, which is what I want. Normally, the larger a covered greenhouse type structure is, the easier it is to keep it from getting too hot and the smaller it is, the harder it is to keep it cool. That's why plastic over a low tunnel isn't as good of an idea at this time of year as floating row cover over a low tunnel---when it is hot during the day, the row cover allows air to flow from the inside to the outside and vice versa so the heat buildup is less. The plastic can be needed at night though when temps are in the 20s and 30s. If you apply the plastic in late afternoon, some heat buildup will occur that will help keep the plants a bit warmer that night, and the plastic helps hold in the heat that has been soaking into the ground all day. Plastic is just hard in our climate because of our weather's erratic nature. Now, if we were in a consistently cool spring climate like you might see in New Hampshire or Maine, I bet the plastic could stay on 24/7 with the row cover underneath it.

George has written an excellent thread on hand-pollination of squash, and when the time comes that people need that info handy, one of us will find it and link it, as we do several times every year. It isn't hard to do, but you do have to watch the air around you while you're doing it, or a squash vine borer moth will fly in and lay eggs on the plants while you have the cover removed temporarily so you can hand-pollinate the flowers.


    Bookmark   March 1, 2012 at 9:22AM
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For hand pollinating squash.

Here is a link that might be useful: George's Instructions

    Bookmark   March 1, 2012 at 10:18AM
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