How to Build a DIY Plant Trellis That Doesn't Suck
This is the summer I urge you to ditch those expensive, cheaply made pine trellises you can find at big box stores. They’re never big enough, they rot after a few seasons, and they are never strong enough to act as a decent trellis. This year, let’s commit to making a long lasting wall trellis that looks completely professional and will save the structure of your house from damage by plants.
The fundamentals of wall trellising
A trellis has two functions: First, to give the plant something to hold onto and direct it where to grow, to help give it support and structure; second, to hold the plant far enough away from the structure to protect it from damage. Plants are resilient creatures that seek structure and will cling to your house siding and gutters if that's what's easiest.
No matter what plant you choose to trellis, you’ll still need to provide upkeep for the plant, whether that’s annual pruning, feeding, or helping it along the trellis. When the plant runs out of trellis, it’s headed for your roofline, and you’ll need to keep that in check, too.
Tools you’ll need for a DIY trellis
To create a wire trellis, you’ll need:
Eye hooks to act as anchors and hold the trellis away from the wall,
Wire or cable to go between the hooks.
Crimps (or stops) to keep it in place.
A crimper to to lock the crimps in. (There are different sizes of wire, crimps, and crimpers, so you should choose based on how heavy the plant will be. As a general rule, I use 20-gauge wire for light plants like Clematis and much heavier 9-gauge for heavier plants like roses.)
Silicone caulk to seal drill holes and prevent water damage.
Velcro tape to assist the plant's growth.
Planning and installing the trellis
To plan out the trellis, sketch the wall you’ll be using with accurate measurements. Start laying in where the anchors will go. You don’t need to start your trellis lower than three feet above the ground. You don’t need to cover your entire wall, either; you can choose where the trellis will go to guide the plants. For instance, a trellis could stretch above your windows and across the wall, to give plants grown on either side a path that keeps them off the windows.
For each of the eye hooks, you’ll want to pre-drill into the siding or concrete using the appropriate bit (and anchor, if necessary). Next, add some clear silicone caulk to the hold and then screw in the eye hook. The silicone should seal the hole so water can’t intrude into the house.
With the eye hooks in place, you can now choose the pattern you’ll use for the wire. You can use a plain grid or diagonal grid, but there are no rules for how you string the wire, meaning you can use any geometric shape you choose. While roses might not follow the shape precisely, smaller vines like jasmine likely will, revealing the shape on the wall.
To set your first wire in place, slide a crimp onto the end of the wire and then loop the free end of the wire through your eyehook and back into the crimp, creating a loop. Slide the crimp as close to the eyehook as you can and then use the crimp tool to clamp the crimp onto the wire. Spool the wire to the next eyehook, cut enough to make the loop, being generous, and repeat the step. Make sure the wire is taut before you crimp it. To accomplish this, it’s nice to have a pair of pliers to hold onto the wire to pull it. Now, you just repeat this process over and over until the grid of your choice is done.
Vining plants come from the nursery tied to a wooden stake, so the first thing to do is remove the plant from that stake. Carefully unwind it, and then remove the plant from the plastic pot and plant it at the base of the trellis. Drape the vine onto the lowest rung of the trellis, and secure it to the trellis using velcro tape. The tape should only be tight enough to hold the vine in place. If it's too tight, it will strangle the plant, so give as much slack as you can. The velcro tape can be readjusted in the future.
Maintenance and upkeep
As the plant grows, you’ll train the plant to attach itself to the wires by using the velcro tape and anchoring it in the direction you want it to go. You can treat it as any other plant by making sure it has food and water, and ensuring it gets pruned when it should.