My Homemade Solar Heated Greenhouse

The solar heated greenhouse is up and running. It’s not totally solar heated but I get enough heat with my creative heating techniques to get my vegetables and perennials going and with a few more tricks I heat the greenhouse in mini climate area areas until the temperatures become more consistent in NW PA. With the price of heating it pays to experiment. Red and purple
Creative Commons License photo credit: quinn.anya

Today I started my tomato and pepper plants. Normally you start both of these plants six to eight weeks before your last frost but I like large plants to set out and I trade my plants for perennials so I start my plants now and use the tomato and pepper re-potting method. In my growing zone you normally plant your tomatoes and pepper plants from May 15 to 31. Even in May its wise to be prepared for a late frost and cover you more tender plants at night. IMG_3559
Creative Commons License photo credit: rudy.kleysteuber

I also collected more milk jugs from friends and family to fill with water and lined another wall of my greenhouse and one side of the mini greenhouse I setup inside the larger greenhouse. The smaller greenhouse is for my perennials that are requiring a little more heat to grow and this should supply the extra heat needed.

Milk jug solar heating has been my primary heating source in the greenhouse for four or five years but I have to admit this winter has challenged the heating. I may have to break down and add a small electrical heater if this cold doesn’t break soon.

My first batch of perennial plants that I am raising from seed are now 3 inches tall. I will move them into the smaller portable plastic greenhouse I put up inside the larger greenhouse and start a new crop of perennial seeds. I have been giving my perennial seeds a cold treatment in the refrigerator as shock treatment to force them to germinate and wake up earlier than they normally would. My first group of herbs are also doing well.

I also have three batches of compost brewing in the back of the greenhouse. They should be ready in a week, just in time for another round of seed planting.

As spring nears I am slowly starting my plants, perennials and herbs first. Next will be flower that require a longer seed starting period, then on to the regular seeds that take six to eight weeks to be ready to set out in the gardens. It feels great to be back out in the greenhouse playing in soil and making plans for the new gardening season.

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18 responses to “My Homemade Solar Heated Greenhouse”

  1. Sam

    I love this blog, when are you coming out with a book, I need help now before spring comes!! What do I do with the milk jugs again?

    Thanks for all the help – I want a garden that produces this year!

  2. Could you post or email me a picture of your setup? I’m interested to see if you stack the jugs or what. I’ve seen others use 55gal drums and paint them black to absorb even more heat.

  3. Hi Sam

    You are right, now is the time to plan your garden. Just ask and I will answer any question you have. Check back in two days or email and you will see my milk jug article. Or contact me and I will send it to you. ts amazing what all you can do with a plastic milk jug in the garden.

    My ebook will be out in an month or two but my free reports will be available in a few days. And I will be waiting to see photos from your successful garden you grow this year! Thanks for stopping by, Denise

  4. Denise

    Hi JoAnn,

    My greenhouse still has a bit too much snow for a good photos, but I will add one later.

    The milk jugs will stay in place from the water and I usually only use one row. But I did use a double row one winter when it was really cold. To do that I placed a double row of milk jugs the whole way down one side, then placed wire racks on top of them and set another row of milk jugs on that. The wire racks can be store bought or old refrigerator racks (I pick them up at a junk yard for free)

    I have seen 55 gallon barrel used and smaller plastic jugs that hold about 10 gallons of water. The smaller jugs are easier to move if you have to.

    Thanks for stopping by, Denise

  5. solar amn

    You can’t beat home grown tomatoes. My dad grows them. They are mouth-watering. So much tastier than those bland supermarket varieties

    solar amn’s last blog post..Solar Energy For The Home

  6. Denise

    I totally agree. There’s a sweetness and flavor that just does not come from the store bought tomato. Plus with homegrown you know if any chemicals were used for growing or insect control.

    Thanks for stopping by, Denise

  7. How does milk jug solar heating work?

    Chris’s last blog post..Winter Hiking in the Proposed addition to the Hickory Creek Wilderness in the Allegheny National Forest

  8. Denise

    Hi Chris,

    If you use clear milk jugs and fill with water the water will capture the warmth from the sun. In the evening this heat will add enough warmth to the greenhouse to keep it above freezing in our zone 5 climate. The temp today is 50 degrees.

    When I have plants that need a warmer temperature to grow I either add more milk jugs or set up a mini greenhouse in the first greenhouse and that will give me a warmer growing climate.

    One day I would like to get a mini solar panel or wind power for heat, but until then, this works!

    My greenhouse has about 35 milk jugs at the moment and one small mini greenhouse sitting inside for my seedlings and cuttings. Denise

  9. Hello Denise,

    The milk jugs filled with water to store heat sounds great. Is it best to have them on the south or north wall? I’m thinking the south to get as much heat as possible, but then I don’t want to rob the plants of any light so maybe the north is best.

    Thanks, Mike

  10. This is a great low-tech solution. Good luck and thanks for the info

    Chris’s last blog post..Thinking Green This Spring

  11. Denise

    Hi Mike,

    I use the southern exposure, but anyside will really do… depending on how your lighting is and how many milk jugs you need!

    I also place the jugs on the ground (on black plastic to catch more sun) and they rarely ever interfer with the plants getting sunlight.

    Thanks for stopping by! Denise

  12. Denise

    When you have winters like we can have, you learn to get creative. I am amazed by how much heat these plastic jugs can create. Denise

  13. jj

    does it have to be a milk jug or can it just be plastic

  14. Any plastic jug will work. Black or clear are the best colors in my opinion. I use milk jugs because they are easy to get and free.

  15. John

    WHich is better, clear milk jugs or painted black?

  16. Denise

    I use the clear jugs myself. I do know people who use black. I really don’t know which is better.

  17. teresa

    Hi, we have a 32×32′ greenhouse with clear fiberglass on the outside, and 6mil uv plastic as a vapor barrier on the inside. We use the milk jugs stacked from wall to wall, floor to ceiling on the N wall. We also insulated the heck out of that wall, ending with foil bubble wrap facing the jugs to reflect even more light/heat to the jugs. We laid the bottles on their sides, and stacked them, holding each stack in place with a long stake in the ground going through the handles of the jugs. The butts of the bottles are sprayed black, but the sides are left white, again to refract more light/heat to the bottles beside themselves. The W and E walls have bottles 2 rows high, same paint job, but no outside insulation. S wall is only one jug high, and all black. So far enough heat at night to keep out any freeze. Teresa

  18. Denise

    Its amazing how much the milk bottles can help retain heat. Denise

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