Most squashes (Cucurbita spp.) have long, creeping stems* and use up a lot of space in the vegetable garden. That’s especially true of pumpkins, whose stems can reach 25 feet (7.5 m) in length with large leaves 15 inches (40 cm) and more in diameter. Even when you space them according to the usual recommendation, 4 to 6 feet (1.2 to 1.5 m) apart, you’ll soon find yourself with pumpkin stems creeping all over the garden and big leaves shading out other crops.
*There are also non-vining types of squash, called bush squashes, such as zucchini (courgette), that stay put in the garden and don’t require as much space.
But have you ever thought of growing squash vertically, that is, letting them grow up some sort of support, like a trellis, a plant tipi or an obelisk? Squashes are climbing plants in the wild, with tendrils that wrap around thin supports and hoist them into the air. You can easily let them do the same in your home vegetable garden.
For squash with small fruits, like summer squash, that’s easy and logical, but what about pumpkins or other squash with big fruit? The weight of the fruit hanging in the air is such that it risks either breaking off or pulling the whole plant to the ground well before it reaches maturity.
So why not direct pumpkins to an open, sunny space that is usually ignored by gardeners: the roof? True enough, the roof of your house may be a little too high and not readily accessible, but what about a garden shed or perhaps a garage? All you have to do is to fix solid cords between the ground and the roof and encourage the stems of the pumpkin to mount them. And it’s not much of an effort: once the first tendrils have taken hold, pumpkin stems will run right up the cord on their own.
Once the stems reach the roof, you’ll no longer have to try and control their growth. Usually, you can simply let them ramble around on their own. Talk about a green roof!
In cool summer areas, growing pumpkins on the roof is actually advantageous on another level: it’s warmer up there and pumpkins are heat-loving plants that produce more and bigger fruits in hot weather. However, there’s a limit to how much good heat can do. In areas where daytime rooftop temperatures normally exceed 95 °F (35 °C) on a daily basis, there’ll be little successful pollination and therefore, few fruits. So the “rooftop technique” is not as useful in regions with really torrid summers, like Phoenix, Arizona, or Las Vegas.
Of course, you’ll need a ladder and probably an assistant to help you harvest the huge, heavy pumpkins that grow on your shed’s roof, but is that so much to ask in exchange for increased production … and all the space gained for other vegetables in the garden below?