Car Greenhouse - Growing Food, Extending the Season and Succeeding With Tropicals

About: I live in a forest garden by the sea in an old Celtic longhouse in the Baie de Mont Saint Michel, France, where we raise quail, rare breed chickens and pigeons organically. I was born in England, the furthes...

Like most people who live in old vernacular houses or in a small flat, we are very limited on window space. Our house was built over 300 years ago, when glass was not an option, so each room only has one window around which to start plants, vegetables, fruits and flowers indoors. The best use of this space I have ever seen was by my parents, who live in a similar age of house. When we were staying with them one Winter, I counted 150 lettuce and herb plants on the window sills! Needless to say they had fresh salad greens every day.

Although we do have several home-made greenhouses including one made from reclaimed windows (see above), in early Spring it is not warm enough within them to germinate vegetables such as tomatoes, bell peppers, cucumbers and courgette/Summer squash. It would also be impossible to start such tropicals as turmeric, ginger and sweet potato, which require initial high temperatures. As we only eat organic food and turmeric is 35 Euros a kilo (nearly $40), this will give you an idea of how 'growing our own' makes a significant difference to our budget.

One day when I was trying to figure out if adding an exterior mini greenhouse to the outside of the window would allow me more growing room, I suddenly realised the solution was staring me in the face - our car parked out front.

Step 1: Using the Heat of the Car to Germinate Tropical Edibles and Medicinals

Our car is pretty much a work horse and is only used once or twice a week at most to go out to the farm to get milk, collect pallets and do our weekly shop. The rest of the time it sits out in front of the house, in full sun. I checked the temperatures inside and even in March on a sunny day they can rise to over the 25 °C or 77°F needed to start turmeric from its rhizome. It is also easy within the car to provide the heat and humidity needed for sweet potato and ginger.

I keep a thermometer within the car during the whole time I have my plants in there, to check on temperatures. In the early evening, when the car begins to lose heat, I have the option to either bring my plants indoors or cover them with a fleece. On occasions when we are not expecting to find pallets and therefore do not need all the available space, I leave the plants in the car when we go out.

Of course if you want the maximum growing area, then the best greenhouse car is an estate or break, like ours but most types of car or RV will give you a good even daytime temperature and good light levels within the body of the vehicle. For brilliant light to keep the water temperatures high in such tropicals as ginger and turmeric, the latter which I find germinates better in warm shallow water, I place them on the dash. Similarly I can place my whole growing pot with my sweet potato suspended over the water in the body of the car to get a good even temperature, without the danger of too much light scorching the emerging shoots.

Step 2: Using the Car With the Baggie Method

I have also used the baggie method to grow goji from seed (see above). This is a way of germinating seeds by use of a damp paper towel on a china plate inside a sealed plastic bag. I then place the whole thing inside the car but away from direct light.

Using a combination of car, kitchen and greenhouse, you can get at least a month's extra growing in early Spring and a jump on the whole food production cycle.

In colder climates you can also start edibles and edible medicinals such as ginger, turmeric, pineapples, mango and passionflower, which would otherwise be difficult to grow without a heated greenhouse. Once acclimatised in their first season and when grown from rhizomes or seed, these plants will then be able to survive in a cool glass greenhouse, with just a layer of fleece or straw throughout the Winter months.

So if you are going to work everyday by bicycle, train or bus and leaving your car out in the road, then why not make better use of it as a greenhouse for growing food early in the season or to jump start some of the more exotic plants, normally outside your growing zone?

If you would like to see how we grow turmeric in a cool climate, I have included our film and also this link will take you to detailed information on how we built our own glass greenhouse from recuperated windows:

All the very best from Normandie,




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    4 Discussions


    2 years ago

    Such a good idea! I currently have two dead cars outside and I live way up in the mountains in Colorado. This could be a great way to give our plants a little extra sun during the day, and to start some seedlings. :)

    1 reply

    Reply 2 years ago

    Hi there, It works really well, particularly as this year here in France we have had a really rubbish Spring with temperatures that would be great for November! Good luck and so happy you found this useful, Sue


    2 years ago

    What a great idea! For those of us on the farm with continually "broken down" vehicles, this is a great way to supplement the garden space...especially in the winter sun!

    1 reply

    Reply 2 years ago

    Thanks so much for your comments! I am always looking for places to raise plants and seeds and a car seemed to me so logical. You could actually make quite a nice market garden business out of it if you have enough vehicles!! All the best, Sue