The term "grow tube" may not be grammatically correct. "Growing tubes" is what you do in a drought after the plant dies, and we want to avoid a crop of empty tubes. So, grow tubes it is.
Grow tubes are 30 or more inches of plastic material which are shipped from the factory flat, or nested and form a 3-4 inch tube when assembled. All models are reusable. They are designed to admit enough sunlight to permit vine development. Water enters at the top of the tube.
First generation tubes were heavy, rugged devices which were designed to protect young trees. These tubes fostered the idea of grapevine application, but they are very expensive and inappropriate for vineyards. They are more opaque, which may be fine for a young tree trunk, but doesn't make sense for a new grapevine. Finally, they are solid and seamless. They deny essential access to the plant until it may be pruned back enough to slip off the tube (in other words, the following spring).
The newer, lighter, less expensive models (30-65 cents US depending on quantity purchased) differ principally in the way they fasten when assembled. Some have built in locking tabs and others have to be stapled. Both types are fine at installation, but during the season, the tab model permits easy access to the young vine and the stapled model is a struggle (unless it's a half tube as described below).
the second season we used grow tubes, cut them to half length for grapevines (the picture above was taken before we started doing so). A 15" tube provides all of the necessary protection. The final 15 inches of the 30 inch tube actually serve to increase stress on the vine due to crowding of growth, overheating, and lack of air drainage. Halving the cost of each tube is also attractive.
The tube should be placed over a newly planted vine and tied to a stake using holes punched in the tube. The combination of a temporary, low trellis wire and a short stake at the bottom of the tube will also suffice. The objective is simply to provide enough stability at the base of the tube to prevent the interior tube walls from coming into contact with and damaging buds and new shoots.
Grow tubes provide us with several new management tools. First, they take some of the guess work out of the question of when to plant. Since new vines will have their own cold frame, they can be planted a couple of weeks earlier than would be advisable without the tube. With the tubes, establishing a good trunk in the first season is more easily accomplished.
Secondly, the tubes provide protection against wind and animal damage during the first few weeks of growth. They provide adequate protection from herbicide applied under the trellis.
Third, and perhaps most important, by reducing some of the stress on the newly planted vine, the tubes may substantially enhance our ability to establish a healthy and vigorous replacement vine among highly competitive and mature neighbors.
In dry weather, don't forget to spray a little water in the tube. Drip irrigation emitters may be installed into the top of the grow tubes by using short pieces of feeder tubing.
Grape clusters set inside the grow tubes near the bottom where you can't see them. They detract from the vigor of the main trunk you are trying to establish. The 15" tube slides up easily to permit removal of clusters and unwanted shoots. The thirty inch tube has to be opened and requires much more time to perform this simple task.
The jury is still out on whether to leave the tube on the vine during the first winter. Some people cite the threat of small rodents building a nest at the bottom of the tube and gnawing on the vine. One fellow Maryland grower suggests leaving the tube in place, but raising the bottom of the tube 2 inches above the soil to prevent the buildup of excess water and assure the presence of enough cold air to keep the vine in dormancy. We have left half tubes installed for two winters without elevating them and without incident.
One grower has written that he opted for making tubes out of freezer paper, a material he describes as meat paper with a plastic coating on one side.
Milk cartons and sections of carpet cores may be used as grow tubes and permanently planted with a young vine. But the need for access to grade level to remove sucker shoots, clusters and extra trunks necessitates cutting this material.
Another alternative is, of course, no protection at all, and some great vineyards have been planted using this approach. But at $3.50 US per grafted vinifera vine, it makes sense to provide 18 cents worth of protection, especially for replacement vines.
NoticeFire Ants build nests in the base of grow tubes.
See Pest Management
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