Hoop house heat management

Saturday was a busy day in the garden.  Like Daphne, my tomato and pepper plants needed planting.  I started the tomatoes on March 8 and the peppers on March 21, thinking I’d be able to plant them in the hoophouse in April.  The plants were big, and one of my pepper plants were just beginning to set buds.  The plants needed to go in the ground, preferably now.  Next year I need to start them each about 2 weeks later.

It is still cold in Maine, I am sure you are surprised to learn.  Our last frost date is in mid-May, but the nights are still cold.  The peppers and tomatoes were started early with the hoophouse in mind as their destination, but even in there it is still pretty cold at night.  What I have come to realize is that my little hoophouse just doesn’t have enough thermal mass to stay more than 2-3 degrees above the outside air temperature.  The soil is much warmer and drier, and it warms up nicely in the hoophouse during the day, but the mass isn’t adequate to hold the higher temps up more than a few degrees through the night, especially since I had to remove an end wall to keep the temps in there below blast furnace on warm sunny days.

Yep, same problem, different manifestation.  There is not enough thermal mass to slow the heat buildup from climbing into the lethal zone.  Last week during our unseasonable hot spell, I removed the north end wall plastic to keep the temps from nuking my poor plants.  The broccoli looks much happier since then, and the lettuce has started to grow again.

But back to the peppers and tomatoes.  What to do?  I’ve been hardening the plants off outside for the last week or so. The plants were spending the entire day outside, and nights in the unheated shed connecting our barn to the house.  The plants were ready to go in the garden IF I could keep them a little warmer at night than the ambient air temperature.  So in the ground they went, with some high-tech polar fleece blankies to keep them warm.  I also used a few wall-o-waters over some of the peppers, and tucked them all in under some floating row cover.  The tomatoes were stripped of their lower leaves and planted up to their necks, then covered in milk jug hot caps until the temperatures warm up and they can be uncovered.  If I had extras, as Daphne did, I would fill gallon jugs with water to absorb heat during the day and radiate it at night.  Unfortunately, I turned all my milk jugs into hot caps, and we rarely have soda on hand.

I set the tomatoes in amidst my lettuce and spinach, hoping that soon I’ll be eating the greens and making room for the tomatoes.  Once the lettuce is gone I will plant some basil and parsley in front of the tomatoes  –perfect companions in my mind!

Still to come in the hoophouse are cucumbers and melon, and later in the summer, late broccoli, Brussels sprouts, kale, swiss chard, and some cabbage.  I hope.


4 Responses to “Hoop house heat management”

  1. Daphne Gould Says:

    I keep thinking that in the spring I have to collect soda bottles from my friends. I never have any myself except from my husbands birthday party. I could always use more. I hope your little plants do well.

  2. Julie Says:

    I am jealous my garden is not even rototilled. They days are longer, but still not enough time to complete every project. The best to you.

  3. mangochild Says:

    I wish it would hurry up and warm! How do you use the fleece blankets? Just lay them over the plants? Don’t they get crushed?

    • Ali Says:


      The “fleece blankets” are really floating row cover –lightweight spun polyester fabric designed just for this purpose. So, amazingly, the plants don’t get crushed. Well, unless there is a freak incident, like a heavy hailstorm that weighs the fabric down.

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