Preparing your Greenhouse for spring planting

As spring approaches I know it’s time to sort my seeds from last year, order any new seeds and get the greenhouse open and ready to use. greenhouse in the snow
Creative Commons License photo credit: wikked one

Once the greenhouse ready for use I let it set for a week to warm up. I use solar heating so the water needs to warm and that takes about a week to take the chill out of any corners.

It takes about two days to clean and organize the greenhouse.

I use the following checklist

  • Wipe down any tables and surfaces with a disinfectant.
  • Check all corners, doors and windows for air leaks.
  • Check tables and indoor cold frames for stability and any needed repairs.
  • Clean and fill clear plastic containers for solar heating
  • Sort and clean any left over pots and planters
  • Check any leftover soil to see if its useable
  • Collect my compost and start more
  • Check plastic used for mini greenhouse climate control
  • Check additional lighting needed for seedlings

Solar heating

I started using solar heating about three years ago. My spring climate is so unpredictable and a cold snap would have expensive gas bills or have to rely on wood heat and go out every three hours to check the fire and temperature. I don’t know about you but the alarm going off at 3 am to head out into sub degree temperatures tends to make me grouchy.

What I did was set up my greenhouse two foot wider on all sides than I wanted. I had my brother dig a trench three foot deep with his backhoe and placed black metal 35 gallon barrels in the ground filled with water. The greenhouse frame and ground heat will keep the water in the barrels from freezing. I cover the barrels with clear plastic after the end of the greenhouse season. This set up keeps the greenhouse at about 40 degrees all winter.

After the greenhouse is cleaned I fill clear plastic jugs with warm water and place on top of the 35 gallon barrels. The sun will keep the plastic jugs at a temperature that is warm enough to heat the greenhouse to a 55-degree temperature. If I need additional heat the use of a small heater or even light will warm the greenhouse another five to 10 degrees.

To insure the jugs get enough sunlight I set the tables I use beside the water containers not on top of them. Later in the spring and summer the tables are placed over the barrels so they do not heat up by the sun.

I will also set up mini greenhouses within the greenhouse for starting seeds that require more heat. I have even used hot beds in the greenhouse for my finicky heat loving seeds and transplants.

One other way I have to heat an area is with a waterbed heating pad. I usually use this only for tomato and pepper plants that germinate better with heat from the soil, but if desperate I will use the heater in the greenhouse.

Greenhouse gardening can be a lot of fun. It gives you a larger selection of seeds and plants that you can grow and extends your growing season.

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6 responses to “Preparing your Greenhouse for spring planting”

  1. Jean-Marie Moes

    Each and every year, as spring nears, I make the promise to myself I’ll finally become the constant gardener. Another year goes by, nothing has changed… but here comes Denise with her “Gardener’s Rake” blog: her no-nonsense, yet logical approach might pretty well be the key that will unlock the door to my gardening haven. Thank you Denise for making gardening sound so simple.

  2. Do you have a photo album of your greenhouse set up? I’d love to take a peek at it. I will soon be moving to a much colder area. Right now I have a small 6×10 hobby greenhouse, it serves me well for the size of property I currently have, and the zone I live in. When I move a much bigger greenhouse is top on my list to build- so I would love to see your set up 🙂

    Happy Gardening,

    Tessa from Blunders with shoots, blossoms ‘n roots

  3. Denise

    Hi Tessa,

    At this time I don’t have photos but I will soon. I also plan to have a build a greenhouse project right here on the website using salvaged items. I use mostly salvaged items, then I can go out and get the extra new greenhouse tools I need and not feel guilty…. (I don’t feel that guilty anyways!)

    I live in a zone 5 so I need my greenhouse and know the feeling of wanting a bigger one. There never seems to be enough room! Denise

  4. Greenhousecarol

    Love your set up for solar heat! I garden in Zone 3 and I wish I had room in my greenhouse for big drums in the ground. Good idea.
    .-= Greenhousecarol´s last blog ..Make Self Watering Planters. Easy Wicking Pots for the Greenhouse =-.

  5. Denise

    Even smaller clear plasic milk jugs filled with water that sit in a place that gets sun will add a lot of heat to a greenhouse.

    I also will set up a plastic mini greenhouse inside of a larger greenhouse to get more heat in one area if I have plants that need a warmer climate.

    There all all kinds of ways to cheat when gardening 😉 Denise

  6. Melissa

    I’m in zone 5. I love the solar heat idea. Definitely going to be toting milk jugs out to the greenhouse. I can’t bury barrels because my greenhouse is a re-purposed school bus. The floor kinda prohibits that. Presently I have to use an electric heater that has a thermostat. I just throw plastic over my shelving and heat a small area.

    We installed an outdoor wood burning boiler to heat the house in the fall. This summer I’ll be digging a trench from the boiler to the bus and hook a car radiator up inside. We are also planning on building raised bed cold frames over the hot water lines that run into the house. Yay for fresh greens year round, just outside my door!

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