Now that your plants are out of the greenhouse and planted in your garden, is it time to close the door and forget about your greenhouse until next spring? That’s how I used to think. Then something happened that changed my thinking completely.
Three years ago I pulled the last plant out of the greenhouse in early June, and closed the door. In mid-July, I went back in to clean up the tables, and my greenhouse was overtaken. From tomato plants to melons, the dome was half filled with volunteer plants, complete with fruit hanging everywhere.
Apparently I had discarded leftover plants in the back corner of the greenhouse the year before, and all those heirloom seeds grew roots down through the mulch, found water in the dirt below, and they were loving their sub-tropical world without any help from me.
Here’s three things you can do in the off-seasons to get more out of your greenhouse:
1. Make a small garden in the back corner of your greenhouse. We dug up the mulch bottom in a 2 foot by 6 foot space in the back of the greenhouse, replacing it with composted dirt, and planted tomatoes, watering them until they found water with their roots. We also planted two musk melon plants and two watermelon plants in the corners of that bed, letting them string along the rolled up side of the length of the greenhouse. These plants produced a huge amount of fruit for such a small garden plot, and rolling down the sides at night kept all the critters out, too.
2. Replant early spring veggies. As September rolls in, your green beans , snap peas, and broccoli will be long gone because of the summer heat. This is the perfect time to replant those veggies in the greenhouse. By the time they get up and going, the temps will be cooler, and these veggies will explode inside the warm greenhouse. Many times we have these fresh veggies well into October, and we live in northern Illinois. There’s nothing like fresh snap peas and hothouse tomatoes in November when everyone else is eating canned or frozen veggies.
3. Use your greenhouse to propagate next year’s plants. We only use heirloom  variety seeds in our gardens, and I don’t have to tell you-the difference in taste is unbelievable! But the true asset to using heirloom seeds is that-unlike the GMO products you get from the big box stores, the seeds of these veggies and fruit can be harvested for next year’s garden. We save a few of the best veggies and fruits, drying them out on a screen in the sun, and we broadcast those seeds in that same back corner of the greenhouse in late November.
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By March, we have so many volunteer plants to pick from, we rarely have to by any more seeds. Once you can recognize each start, they can be re-potted into 4-inch pots for the next spring. This year, not only did we have enough plants for the whole family, we even sold the excess starts out in front of the house.
These are just a few ways we have found to extend our growing season in northern Illinois, but also to incubate new plants for next year. We are NOT professionals, and we have only been at this greenhouse growing for a few years, but by experimenting with the microclimates we have really made leaps in our effort to be self-sufficient. I know there are growers out there that have many other ways to capitalize on greenhouse growing, and I would love to hear from you about your methods. Tell us in the comments section below. Happy gardening, folks!