Make the most out of your vegetables using the proper trellises
Trellises and cages are common plant supports used in vegetable gardens. Many varieties of peas and beans need something to climb, and vine crops such as squash, melons, and cucumbers can produce straighter, cleaner fruit if grown on a trellis.
Many tomato varieties are “indeterminate,” that is, they will continue to grow all season long, sprawling along the ground, unless supported and contained. Even determinate varieties, which reach a certain height and stop growing, benefit from being staked or caged, as their fruits are cleaner and less likely to rot or be slug-eaten, and the plants may be more free of disease.
Trellises for vine crops
Gardeners with small garden plots may bypass crops that need lots of space, planting short-vined or “bush” varieties of melons, squash, and cucumbers. However, many long-vined varieties can be successfully grown in small spaces if they’re trained to grow on trellises. Varieties with fruit no larger than a cucumber, small melon, or small winter squash, up to about three pounds, work best.
Trellises can be made from a wide variety of materials. They generally consist of two vertical supports with a mesh suspended between them to provide support for climbing plants. Metal or wooden stakes should be pounded into the ground deeply enough that the trellis doesn’t tip over in a strong wind. A six-foot stake pounded a foot into the ground will leave five feet of trellis area.
There will be a limit to how much trellised plant matter a pair of stakes can support, depending on the species grown, the vigor of the vines, the type of stakes and how deeply they are set in the ground. Try five or six feet between stakes. For a wider trellis, use three stakes, dividing up the width into two parts with a stake in the middle.
There are many materials that can be used as trellis netting or mesh. Newer products made of plastic are widely available, as are traditional materials such as chicken wire and galvanized fencing. Choose a heavier mesh for larger-fruited and more vigorous crops. Attach the trellis to the supports with nails, staples, plastic locking ties, or lengths of wire.
Plant the vines at the foot of the trellis at the same spacing between the seeds or transplants as if they were going to grow on the ground. Train the vines as they lengthen by weaving the growing tips gently between the openings in the mesh every few days.
A problem for gardeners growing melons on a trellis is that many melons “slip” from the vine when ripe, and may fall to the ground prematurely. To prevent this, make hammocks or slings to support the developing fruit. Use strips of cloth several inches wide. The length of the cloth strips depends on the fruit size. Tie each end of the cloth to the wire loosely enough to allow the middle portion to form a sling. Set the fruit in the sling.
Cucumbers and small squash, such as delicata or acorn, do not slip from the vine, so they don’t need to be supported. Check vine crops frequently to ensure developing fruits don’t become wedged between the mesh wires. Larger squash and pumpkins are too heavy to trellis and should be grown on the ground.
Beans and peas, too, can be grown on a trellis. While some beans are bush types, and some pea varieties are short-statured, others produce long vines that must have a support. A simple trellis of lightweight netting will give adequate support, or attach sturdy wire between the two stakes at top and bottom, then zig-zag twine between the upper and lower wire, so that the vines can twine up these vertical cords. Untreated sisal, cotton, or hemp twine has the advantage of being compostable along with the vines once they are done bearing.
Some gardeners place trellises at an angle to absorb maximum sunlight, and so that fruit hangs freely from the lower side of the trellis for easier harvest. To try this, set the stakes in the ground so that the trellis will face south, and will lean over the soil just north of it. Experiment with engineering this trellis. It may require extra support stakes, depending on how far it is angled.Â
Commercially available conical metal tomato cages are not always up to the task of supporting and containing sprawling tomato plants. Determinate varieties such as ‘Roma,’ which reach a certain size and stop growing, can usually get enough support from these cages. But typically, indeterminate tomato plants grow taller than the cages, and their branches are often long enough to grow outside of the cage and rest their fruit on the ground.
There are many other ways of dealing with the rampant growth habit of tomato plants. Some gardeners leave four or more feet between plants in all directions, mulch heavily with clean straw, and allow the plants to sprawl. Although this method is easy, each plant takes up much more space than it would otherwise, and the fruits are more vulnerable to slugs and rot than they would be if supported.
A simple wooden stake can be an adequate support, if the plant is pruned and tied up to it, as long as it is pounded deeply into the ground. Pruning axillary shoots reduces excessive foliage and thus reduces disease incidence, and also causes fruit to ripen earlier. This system has the advantage of being inexpensive.
Garden supply manufacturers have recently introduced a number of new tomato support systems. Heavier-duty square tomato cages are taller than the old-style conical cage, and they fold flat for storage. Sturdy metal spirals support the main stem of the plant, allowing the branches to extend and droop. Plants grown on spirals, like plants grown on a stake, may need to be pruned and tied to the support. A new plastic coil is intended to be fastened to the top of a tall stake, allowing the tomato plant to grow up along the stake with its branches supported. These items should work better than the traditional conical wire cage, and will be simpler to store.
For gardeners who want to make an excellent tomato support device, cement reinforcing mesh is the best material. Four-foot wide reinforcing mesh makes great tomato cages because of its strength and large four-inch square holes. This mesh is very stiff and difficult to work with. You need heavy-duty wire cutters or bolt cutters to cut it. Wear gloves, a long sleeve shirt and long pants to prevent scratches. Eye protection should also be worn. Cutting the roll of wire at 56 to 60 inches will yield a cage about 18 inches in diameter. Form cages by wiring the cut edges together with lengths of lighter wire, or use pliers to form hooks from the horizontal wires and hook them onto the vertical wire on the other side. These cages will last for many years.
Place any supports when the tomato plants are still young and small, ideally at planting time. The plants will soon grow large enough to use the support. Secure home-made cages in place by sinking two stakes on opposite sides inside the cages.
When using any of these devices, check the plants frequently and guide their growth so that they get the most support.
Jill MacKenzie, Former Extension Specialist, Horticulture
University of Minnesota.