Wilson Grow Tubes have primarily been used on grapevines and pistachios. That is not because grapes and pistachios are the only species that thrive in grow tubes. ALL broadleaf (non-conifer) tree, shrub and vine species grow extremely well in grow tubes. In forestry applications the cousins of almonds (genus Prunus including black cherry, chokecherry, etc), pecans (genus Carya including hickory and northern pecan) and walnuts (genus Juglans including black walnut) all grow extremely fast in tree tubes (the taller cousins of grow tubes).
No, the lack of use of grow tubes on almonds, pecans and walnuts has nothing to do with whether or not these trees would do well in the tubes. It had everything to do with the fact that traditional growing practices for these trees called for planting large (4 to 6ft) bare root trees in the field – larger trees than you would use a grow tube with.
Pistachio growers realized many years ago that growing a tree in the nursery for 2-3 years, pulling it up by the roots, then transplanting to the field is not the way to go. Transplant shock results in slow growth for the first 1-2 years. And the root deformations (j-rooting, circling roots, etc.) that inevitably occur when planting large bare root stock can have long-term consequences in terms of tree health and productivity.
Pistachio growers found that if they plant very small potted planting stock in the field and protect those small trees with grow tubes, they end up ahead of the game in both the short- and long-run. There is zero transplant shock, so the trees quickly catch up with and surpass larger bare root planting stock. Of course the planting stock costs considerably less. And the roots develop on site with no further disruption or damage, resulting in better long-term health and productivity.
Well almond, pecan and walnut growers are – very quickly – starting to adopt this same strategy.
In just the last month I have sold to customers and visited sites where Wilson Grow Tubes were recently installed on almond, pecan and walnut trees. In all cases the trees being planted were 12 to 24 inches tall and were grown in root pruning pots.
What is driving the shift to smaller planting stock? Demand. Consumers have finally figured out the health benefits of eating nuts, and farmers facing and increasingly scarce & expensive water supply are attracted to the benefits of permanent tree crops as opposed to annual row crops. And nurseries are having trouble keep up with demand. So they are changing from the 2 or 3 year production cycles needed to produce a standard bare root tree and instead are producing grafted, high-quality potted trees in under a year.
Without grow tubes this would not be possible. Survival rates for the smaller planting stock would be too low. Moisture stress, rodent damage, and the inability to spray for weeds would make reaping the benefits of smaller planting stock impossible.
Grow tubes make it possible. With grow tubes the survival rates of small stock planting exceed the survival rate of traditional large stock plantings.
Every few years a new group of growers discovers the benefits of grow tubes, and revolutionizes its planting practices to take advantage of grow tube technology. Due to the combination of increased demand for healthy nut products and increasingly expensive water – which in turn created a boom in planting nut trees that nurseries can’t meet with traditional practices – the time for the shift to the small stock + grow tube paradigm is now for pecan, walnut and almond growers.
And once growers see the benefits of the small stock + grow tube system, they’ll never go back!