Potted shrubs sell better, but growing shrubs in a pot is a pain, or at least it has been until now. Woodburn Nursery, Woodburn, Ore. has figured out a way to meet market demand and do it with less manual labor. Using their first-of-its-kind pot-setting rig, a five-man crew can insert about 6,000 "socket pots" per day into the ground, ready to accept potted shrubs and trees.
Tom Fessler, co-owner of the nursery, says "Our initial intent was to try an acre test plot for a year or two. But it worked so well, we're already up to about 65 acres."
Nurserymen have long known shrubs and other perennials planted in pots that are buried in the ground stand up to winter winds and cold temperatures better than those in above-ground pots. But getting the pots into the ground can be a real job. Pulling them out is not much better, especially in wet weather. Imbedding socket pots equipped with spacers makes removal and replacement of pots relatively easy. All you have to do is find a way to get them into the ground the first time.
After watching a neighbor use a post hole digger to prepare holes, Fessler figured there had to be a better way. So in 1999, he headed to his shop. Three years and tens of thousands of pots later, he is on his second rig, one built to set pots up to 16 in. across and a foot deep.
He started out by building a frame on the floor of the shop out of steel tubing that became the main platform.
A trencher wheel mounts next to the platform. Sizing a gearbox for the trencher was the most difficult part of the project, reports Fessler. "The trencher isn't turning very fast, but there is so much torque on it that we kept breaking gears," he explains. "On the second unit, we way oversized the gears. We also went to running the gearbox off the PTO instead of a hydraulic motor. We travel so slow that the hydraulic motor we used was stalling out."
The pot-setting rig excavates a ditch deeper and wider than the pot to be set, lays down a drain tile in the bottom of the ditch and an irrigation hose along the side of the ditch. Workers riding on the platform place pots in the ditch at regular intervals. Other workers walking alongside, set up spray nozzles beside each pot and fill in around the pots. Seven-pound metal lids, also fabricated in the nursery shop, are then placed over the pots to keep dirt out until the planted pots are inserted.
The entire rig floats on adjustable wheels. Raising or lowering the platform varies the depth of the trench from 8 to 12 in. deep, depending on the size of the socket pots being placed.
This past year, placement of the pots in a grid pattern across the field has become even more exacting. The nursery purchased a new John Deere 7410 tractor outfitted with a GPS-based guidance system. The autopilot allows the rig to travel in a straight line at only four tenths of a mile per hour, something manual steering could not do. Fessler is looking forward to automating the process even further.
"We use a cable with clips on it to identify when a pot should be placed in the trench," says Fessler. "We want to program the GPS unit to signal when to drop the pots in the ground."