Northeast Gardening forum→Newbie Gardener: How do I heat greenhouse in New Jersey for winter

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Name: Bala
Central New Jersey (Zone 6b)
Aug 25, 2020 8:25 PM CST
I am relatively new to gardening and have had some success this summer growing vegetables. Apologies if this has been answered elsewhere. I am thinking of buying a 10 x 12 greenhouse from harbor freight which I want to use to store my patio plants, over 20 of them varying from 5 gallon pots to 25 gallons one. I also want to start growing some vegetables in fall/winter as well as use it for seed starting in early spring. Do I need a permanent heating solution or can I get by with an electric heater. Also any ballpark idea how much my electricity bill will go up. TIA for any help you can provide.
Name: Jim
Northeast Pennsylvania (Zone 6b)
My garden feeds my body and soul
Greenhouse Vegetable Grower Seed Starter Container Gardener Peppers Hydroponics
Canning and food preservation Growing under artificial light Region: Pennsylvania
Sep 1, 2020 4:26 AM CST
Hi Bala and welcome to the forum Welcome!

First, there is a greenhouse forum where you will find a lot of threads about greenhouse heating and winter growing.

Most, and by this I mean 99.5%, of greenhouse kits are not designed for over-wintering or growing of plants during the winter in areas that get cold. There is just no insulation. You could heat it, but the cost will be phenomenal. It is like trying to heat your front porch! Also, you would need an alternative light source since the sun is low in the sky and days are short.

Greenhouses designed for year round growing in colder climates tend to be very expensive with expensive insulation and heat gain systems, in addition to artificial light sources. You could build one yourself, but it would take special skills and knowledge and would be expensive to build.

If you want to learn more about winter greenhouse growing, check out this site: They are one of the leaders in year-round greenhouses. They also have a great book that will help you understand how to build/buy a greenhouse for year-round growing.

With that said, you certainly can use your greenhouse as a season-extender in the Fall and to get a jump on Spring with seed starting, but you will need a heater for cooler nights.

Your greenhouse temperature at night will barely stay above the outdoor temperature without a heat source. Remember, most seeds need warm soil between 70-90 (depending on the seed) to germinate. Without the warm soil, they will take a long time to germinate and the germination rate will be much lower. Think of using a heater and seedling heat mats for seed starting.

I know this is not good news for you, but I hope some of it is helpful.

MoonShadows Farm: Good Eats & Treats from the Pocono Mountains
Our PA Food Forest: An edible forest garden in our backyard
Name: Alice
St. Johns, FL (Zone 9a)
Charter ATP Member Master Gardener: Florida Organic Gardener Enjoys or suffers hot summers Dog Lover Hibiscus
Orchids Fruit Growers Tropicals Hummingbirder Garden Photography Container Gardener
Sep 16, 2020 5:46 AM CST
I think perhaps the placement of the greenhouse would have an impact on how heat efficient it is. Back in the early 70's I was living on the Eastern Shore of Maryland. We put a Turner Greenhouse against the house on the southeast side, it was not attached to the house, it just abutted it so it was protected from the NW winds. It got the morning sun and heated up quickly on bright days. I used a small space heater on cold nights and never lost any of my tropical plants. The floor was just the soil and that held moisture and increased humidity and also worked as a heat sink. I would say the space heater kept the temp around the low to mid 50's. One time when we had an extended period of freezing weather with no sunny days I did put a second space heater in there. My main emphasis was just on keeping plants alive and out of dormancy so I didn't have to start over again each spring. This worked for me. I grew a lot of rare ferns, some orchids and large rex begonias and whatever else fit in there.
Minds are like parachutes; they work better when they are open.
Name: tom
dartmouth MA (Zone 7a)
Sep 28, 2020 10:52 AM CST
watch Nigel Saunders on youtube.

hes renowned bonsai and tropicals grower, from Toronto Canada lol

uses a small greenhouse and a plant room if not for his garden.

he keeps the greenhouse adequate with a small buddy heater/electric
and he grows tropicals in it. i thknk for the winter he might bring a lot of those to conservatory, but check out his videos. he does winter tours of the little greenhouse, etc.

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