Now that you know how to cool your greenhouse this summer, what are you going to fill it with? Here are 10 ideas for making that greenhouse produce more income for you:

1. Start more transplants. New growers often assume that you plant in spring and harvest the rest of the summer. Not so. Succession planting is the key to success in market farming, but it is rarely given the recognition it deserves. The fact is that in most places, there are crops that can be planted every two or three weeks all summer long to provide a continuous supply. Which crops? Unfortunately, there's no simple formula for what you can succession plant. It depends on your climate and even on your weather this year. If you aren't sure what will work for you, pay attention to what other growers are offering at your markets.

If broccoli is still available from some growers long after you have harvested yours, get out there and plant some more! In general, in the cool north, cole crops, greens, lettuce, daikon, beets, and annual herbs such as dill and cilantro can be succession planted. In hot areas, you can't succession plant the cool-weather crops, but you can keep fresh plantings of hot-weather crops that either get harvested or that suffer insect or disease damage. Basil, squash, cucumbers, and tomatoes are good candidates for at least a second and possibly a third planting later in summer. Flowers are simpler in hot climates. Almost all the summer annuals, including zinnias, celosia, sunflowers, rudbeckia, and salvia can be succession planted for a longer season of fresh flowers.

2. Now is the time to propagate perennials and woody plants. Use the greenhouse to root cuttings taken from actively growing plants. A neat trick is to use a forsythe pot. Get two terra cotta pots, one a few inches bigger than the other, and plug the hole securely in the smaller one. Place it inside the bigger pot, and fill the space between the pots with sand. Fill the small inner pot with water, and stick your cuttings into the sand, which will be kept evenly moist, creating the perfect environment for rooting. After your cuttings root, grow them in 4-inch pots or larger in the greenhouse until fall, when they can be planted in their final location or lined out in a field to grow into a bigger size before their final transplant.

3. Grow sprouts. Pea shoots can be grown in a greenhouse all summer. Buy peas from a reputable supplier that tests for pathogens. (We use International Specialty Supply at 800-A-SPROUT.) Soak the peas overnight in clean water. Fill trays with soilless growing medium (do not use compost made from manure because of the risk of contamination by pathogenic bacteria) and moisten it. Spread the peas, shoulder to shoulder, in the trays. They will grow quickly, and can be cut in about 14 days, at 5-6 inches tall. Restaurants like pea shoots as garnish and salad additions.


4. Beat the bugs. If you have plants that always seem to succumb to insects or weeds when planted outside, start some in the greenhouse in 4-inch pots and grow them until they are big enough to withstand grasshoppers, cutworms, flea beetles, or whatever else might cut them down.

5. Dry flowers for sales in fall. Make a tent out of black plastic or landscape fabric and hang flowers upside down to dry. The heat from the black cover and the air movement from ventilation fans will dry them quickly while the darkness will keep the colors bright. Good choices for drying by hanging include larkspur, helichrysum, yarrow, sunflower ‘Sunbright', celosia, feverfew, tansy, statice.

6. Grow a crop of mid-summer lilies or callas in pots. It may be too hot outside by now to get these beauties started, but if the greenhouse has been successfully cooled to below 90°F, you can grow them there. Callas need it a bit cooler. Both can be grown for cutting or to sell as potted plants.

7. Grow autumn-themed ornamentals. You know how popular fall decorations have become. Pumpkins and gourds are only the start of what people will buy in fall. Growing in popularity are the big, colorful broom corns and sorghums. You can start the seeds up to 10 weeks before your first frost date. Actually, you can direct seed these plants in the field early in summer, but by mid-summer, your soil may be too warm for good germination so you can start them in big cells in the greenhouse. Most of these grains have maturities of 100 to 110 days, but you don't have to wait till they are fully mature to harvest them. As soon as the seeds develop and the color is good, you can cut them. For drying, wait until the seeds have filled out. There are many varieties that fit into this category. The best choices are from Germania Seed Company (800-380-4721); and Johnny's (207-437-4395).

8. Grow perennials for fall market sales. Buy plugs or bareroot plants or start your own seeds now, and move them into bigger pots as they grow. By the time the weather cools and people start thinking about planting again, you should have plants ready for sale. It's especially useful to be able to offer plants of varieties that your customers have admired over the summer in your cut or dried flower offerings; just be sure the plants are hardy in your zone.

9. Grow a late crop of tomatoes and basil in grow bags or ground beds. If you start now, you can have a nice crop of tomatoes in the greenhouse after your field tomatoes have been killed by frost. Inevitably, an early frost is followed by Indian summer, so the greenhouse only has to protect your plants briefly to be able to extend the tomato and basil season by several months. Last year, we had a late crop of tomatoes in an unheated greenhouse and we sold them until November.

10. Start your fall garden. You may have just finished getting your summer crops in the ground, but that doesn't mean you can slack off. Fall is just around the corner. Most cool-weather crops have to be started in July or August to reach maturity in the cooler days of autumn.