Saturday, February 2, 2019

Garden Trellis

My vegetable gardening style is on the wild side.  I give maybe too much weight to reseeded native flowers over food producing plants.  I start out with grand expectations of neat rows, but inevitably weeding the garden becomes less important as other tasks loom.  In fact this year I got things nicely cleaned up with weeded and fertilized beds and mulched paths.  Unfortunately reality struck with a cool wet spring that offered few pleasant days to keep the garden neat and clean.

I got the garden all cleaned up in April of 2018 with great intensions
 for keeping it neat, but ...
One way to bring order to the garden is to add visual structural elements.  These add focal points or visual anchors that rise above the clutter.  In past years I've used fallen limbs to create tripods to support beans, cucumbers and tomatoes.  Since these were not well anchored, they end up falling over as the season wears on.  This year I decided to build some semi-permanent tripods that could be left standing for a couple of seasons and could be easily repaired if and when the time comes.

Schematic for my garden trellis.  Parts include 2x2 wooden legs, 3" diameter PVC pipe,
 6" wood square, some 2.5" deck screws and a bag of coarse sand.

I liked the idea of using tripods.  They are easy to build and structurally sound.  Here is a schematic plan that I came up with for my tripod trellises.  I wanted to build it out of 2 by 2 cedar, but it was not readily available in long lengths.  Being somewhat impatient I got 2 by 8 pressure treated boards that I ripped into 3 1.75" wide pieces about 7.5' long.  Before ripping into thirds, I cut off a 6" piece (actually 6" x 7.5") to make the top support.  I trimmed this rectangular piece into a hexagon on the band saw and angled 3 of the faces at 12° to match the angle of the tripod (see the diagram).

Completed intallation of tripod legs.  Having the PVC sleeve
 above the soil level helps keep the sand clean.
 Rather than driving the trellis directly into the ground, where constant contact with wet soil would accelerate rotting of the wood, I put in a length of 3" PVC drain pipe that I would later fill with sand to make well draining fill that would also hold the trellis firmly in place.  (Note that the thinner schedule 40 PVC drain pipe can be used rather than schedule 80, since you are just forming a soil barrier.)  To further improve the weatherability I also painted the lower 2 feet of the wood with a water seal coating. 

My biggest mistake last year was getting started too late in the season, after the garden had started growing. To put in the PVC liners in the established garden I used a trenching shovel (about 3" wide) to dig a fairly narrow hole in at a roughly 12° angle and 16-18" deep.  I then used the PVC tube itself to remove the last bits of the soil and get a firm fit.  The other two liners were put in 31" away from the first to form an equilateral triangle (see the diagram). 

The top support is attached to the legs
with 2.5" deck screws.  These are easily removed
 if I needed to replace one of the legs.
After the liners were in, it was time to position the legs of the tripod.  With the 3" lined holes there was sufficient wiggle room to get the legs to align.  The top hexagonal support was attached to the legs with 2.5" deck screws. The screws were prepositioned about 9" from the ends of the legs so that I only had to drill them into hexagonal support (into the angled faces).

The completed trellis, with a spiral of twine,
is ready to support these cucumbers.
With the top support attached and the legs in their PVC sleeves I filled in the space between the sleeves and legs with coarse sand.  First I put in about an inch of sand as a base under the legs then finished by back filling with sand to the top of the sleeve with occasional tapping to make sure the sand was evenly and firmly distributed. It took a little over a half cubic foot of sand to to do 4 tripods (12 holes).

Even with this late start I was able to train the tomatoes and cucumbers onto the trellises that I had built around them.

I tied some rubber balls to the blunt top ot the tripod using fishing line. 
The lightweight balls won't damage the plants if they fall off.

Now I am again getting ready for a clean start in the garden.
It's February and the trellis are ready to go.  Well, maybe in a couple of months.