How to Build a Garden Trellis for Climbing Vegetables and Flowers
A tomato plant grown on the ground produces 15 to 25 pounds of fruit per season. The same variety trained on a trellis produces 30 to 50 pounds, because vertical growth increases air circulation (reducing disease by 40 to 60 percent), exposes more leaves to sunlight, and keeps fruit off the soil where rot and pests destroy it. Cucumbers grown vertically produce straighter fruit and take up 70 percent less ground space than vines allowed to sprawl. A trellis pays for itself in increased yield within a single growing season. The three designs in this article cost $15 to $45 in materials and take 1 to 3 hours to build.
Matching the Trellis to the Plant
Heavy climbers such as indeterminate tomatoes, winter squash, and watermelon require a trellis with a frame made from 2x2 or larger lumber and a wire mesh panel for support. Light climbers such as peas, pole beans, and morning glories grow well on a simple string trellis or a lightweight wooden grid. Medium-weight climbers such as cucumbers, summer squash, and climbing roses need a frame of 1x2 or 2x2 lumber with wire or twine support.
The trellis height should match the mature height of the plant. Indeterminate tomatoes reach 6 to 8 feet and need a trellis at least 7 feet tall. Pole beans reach 5 to 6 feet. Cucumbers reach 4 to 5 feet. Peas reach 3 to 4 feet. Building the trellis taller than the plant needs is better than building it too short; a plant that outgrows its trellis will cascade over the top and create a tangled mess that is difficult to harvest.
Design 1: Wire Mesh Panel Trellis (for Heavy Climbers)
This design uses a cedar frame with a galvanized wire mesh panel attached to the face. It supports tomatoes, cucumbers, squash, and melons. The overall dimensions are 4 feet wide by 7 feet tall. Material cost: $35 to $45.
Materials
Two 2x2x8 cedar boards ($5 each) for the vertical uprights. One 2x2x8 cedar board ($5) cut into three horizontal cross braces. One 4x7-foot galvanized welded wire mesh panel with 4-inch grid openings ($18 to $25 at Home Depot or Tractor Supply, sold as "welded wire fencing" or "cattle panel"). One box of 1.5-inch exterior deck screws ($8). Two 4-foot pieces of 1/2-inch rebar ($3) for ground anchors.
Cutting the Frame
Cut the two vertical uprights to 84 inches (7 feet) each. Cut three horizontal cross braces from the remaining 2x2: one at 48 inches (4 feet) for the top, one at 46 inches for the middle, and one at 46 inches for the bottom. The middle and bottom braces are 2 inches shorter than the top brace to allow the uprights to extend 1 inch below the bottom brace on each side for ground insertion.
Assembling the Frame
Lay the two uprights flat on the ground, parallel, 48 inches apart (measured from the outside edges). Position the bottom cross brace 6 inches up from the bottom of the uprights. Position the middle cross brace 42 inches up from the bottom. Position the top cross brace 82 inches up from the bottom (2 inches down from the top of the uprights). Drill pilot holes through the uprights into the cross braces and drive 1.5-inch exterior screws, two screws per joint. The frame should be a rigid rectangle.
Attaching the Wire Mesh
Lay the wire mesh panel flat against the frame. The mesh panel is typically sold in 4x8-foot or 2x8-foot panels. A 4x8-foot panel needs to be trimmed to 4x7 feet with bolt cutters ($12) or heavy wire cutters. Position the mesh so it sits flush with the top and sides of the frame. Attach the mesh to the frame with galvanized U-shaped fencing staples ($4 per box). Drive staples every 6 inches along all four edges, stapling through the mesh wires and into the cedar frame. The staples must penetrate at least 0.5 inches into the wood to hold securely.
Installing in the Garden
Position the trellis in the garden bed where the plants will grow. Drive a 2-foot piece of rebar into the ground at each side of the trellis, 12 inches deep, leaving 12 inches above ground. Tie the trellis uprights to the rebar stakes with galvanized wire or zip ties. The rebar anchors prevent the trellis from tipping under the weight of mature plants and wind loads. In windy locations, add a third rebar stake at the center of the trellis for additional support.
Space the trellis so the wire mesh faces the prevailing wind direction. Plants trained against a solid panel catch more wind than those on an open frame. Facing the mesh into the wind allows air to pass through the gaps, reducing wind stress on the plants.
Design 2: A-Frame Trellis (for Raised Beds)
An A-frame trellis straddles a raised bed, supporting plants on both sides. The angled panels increase the growing area by 100 percent compared to a single flat panel, because plants climb both faces. The overall dimensions are 4 feet wide at the base by 5 feet tall at the peak by 4 feet deep. Material cost: $25 to $35.
Materials
Four 2x2x8 cedar boards ($20 total) for the legs and top rail. One 1x2x8 cedar board ($3) for the cross braces. One 4x5-foot piece of galvanized wire mesh or nylon trellis netting ($8 for netting, $15 for wire mesh). One box of 1.5-inch exterior screws ($8). Two exterior hinges ($5) for the top connection.
Cutting and Assembly
Cut four 2x2 boards to 72 inches (6 feet) for the legs. The legs will be set at a 60-degree angle from the ground, producing a peak height of roughly 62 inches and a base width of 48 inches. Cut one 2x2 to 48 inches for the top rail. Cut two 1x2 boards to 44 inches for the mid-panel cross braces.
Build each panel separately. For one panel, lay two legs flat with their bottoms 48 inches apart. Position the top rail across the angled tops of the legs. The top rail connects the two legs at the peak. Drill and screw through the top rail into each leg with two 2-inch exterior screws. Position the mid-panel cross brace 36 inches up from the bottom of the legs and screw it in place. Attach the wire mesh or netting to the frame with staples or zip ties.
Build the second panel identically. Connect the two panels at the top with two exterior hinges. The hinges allow the A-frame to fold flat for winter storage. Open the A-frame and position it over the raised bed. The base of each panel sits on the soil at the edges of the bed. Drive a 12-inch stake into the ground at the bottom of each leg to prevent the panels from sliding outward under the weight of plants.
Design 3: String Trellis (for Peas, Beans, and Light Climbers)
A string trellis is the simplest and cheapest design. It consists of two vertical posts with horizontal strings running between them. Peas, pole beans, and morning glories grip strings naturally with their tendrils. The overall dimensions are 6 feet wide by 6 feet tall. Material cost: $12 to $18.
Materials
Two 8-foot 2x2 cedar posts ($5 each). One 50-foot roll of jute garden twine ($4) or nylon trellis cord ($6). One box of 1.5-inch exterior screws ($8). Two 12-inch pieces of rebar ($3) for ground anchors.
Installation
Drive the two cedar posts into the ground 6 feet apart, burying them 18 inches deep. The posts extend 78 inches above ground (6.5 feet). Drive a rebar stake alongside each post, 12 inches deep, and wire the post to the rebar for stability. A post set 18 inches deep in firm soil supports a mature bean or pea crop without additional bracing. In loose sandy soil, increase the burial depth to 24 inches.
Screw a 2-inch exterior screw into the top of each post, leaving the screw head protruding 0.25 inch. This screw serves as an anchor point for the strings. Screw additional screws at 12-inch intervals down each post, creating anchor points at 12, 24, 36, 48, and 60 inches from the ground.
Tie the twine to the top screw on one post, stretch it across to the top screw on the opposite post, and tie it off. Repeat for each row of screws, creating horizontal strings at 12-inch intervals from top to bottom. For additional support, run vertical strings every 8 to 10 inches between the horizontal strings, tying each vertical string to every horizontal string it crosses. The resulting grid of strings provides plenty of grip points for climbing tendrils.
Jute twine costs $4 per 50-foot roll and is biodegradable, which means you can cut it down and compost it with the plant debris at the end of the season. Nylon cord costs $6 per 50-foot roll and lasts multiple seasons but must be collected and stored. Jute is the better choice for annual vegetables. Nylon is the better choice for perennial climbers such as clematis and climbing roses that remain on the trellis year-round.
Training Plants onto the Trellis
Most climbing plants do not automatically find the trellis and climb it. They need initial guidance and occasional redirection as they grow.
Tomatoes
Indeterminate tomatoes do not have tendrils and cannot climb on their own. Tie the main stem to the trellis with soft twine or tomato clips ($5 for a pack of 50) every 8 to 10 inches as the plant grows. Prune suckers (the small shoots that grow in the angle between the main stem and each leaf branch) to a single leader for the strongest vertical growth. A single-leader indeterminate tomato trained on a 7-foot trellis produces larger fruit and ripens earlier than a multi-stem plant.
Cucumbers
Cucumbers have tendrils that grip wire mesh and string naturally. Guide the initial vine toward the trellis by gently wrapping it around the bottom wire. Once the vine reaches 12 inches, it will climb on its own. For heavy fruiting varieties such as Marketmore or Straight Eight, support each cucumber by tying it to the trellis with a strip of old T-shirt fabric. The fabric tie prevents the weight of the fruit from pulling the vine off the trellis.
Pole Beans
Pole beans wrap their tendrils around any support within reach. Plant seeds 2 inches from the base of the trellis. When the seedlings are 6 inches tall, guide the strongest vine toward the nearest string or wire. The plant will climb from there. Harvest regularly to keep the vine productive; mature beans left on the plant signal it to stop producing.
Climbing Roses and Clematis
Climbing roses do not have tendrils. They produce long canes that you must tie to the trellis manually with soft garden ties ($6 per roll). Space ties every 12 inches along the cane. Train the canes as close to horizontal as possible; horizontal canes produce more flowers than vertical canes because horizontal growth encourages the formation of lateral flowering shoots along the entire length of the cane.
Clematis climbs by wrapping its leaf stems around thin supports. Wire mesh with 2 to 4-inch openings works well. String trellises also work if the string is no thicker than 0.25 inches in diameter. Clematis cannot grip thick wooden boards or large-diameter rope.
End-of-Season Care
At the end of the growing season, cut all plant material off the trellis and compost it (unless the plants had disease, in which case burn or bag the debris). Remove any remaining twine or ties. Inspect the cedar frame for loose screws, cracked joints, or rot. Tighten loose screws and replace any cracked boards. Cedar frames last 10 to 15 years with annual maintenance.
Wire mesh panels last indefinitely if made from galvanized steel. If you used non-galvanized wire, expect rust to weaken the mesh within 3 to 5 years. Replace rusted mesh before the next growing season; a mesh panel that fails mid-season under the weight of mature plants is difficult to replace without damaging the plants.
Store A-frame and string trellises indoors or under cover during winter. Fold the A-frame panels flat and lean them against a garage wall. Remove the string from string trellises and store it in a dry place; jute twine left outdoors through winter will rot and break before the next season.
Apply a coat of raw linseed oil ($7 per quart) to the cedar frame every 2 to 3 years to maintain moisture resistance. Apply the oil in late fall after removing plant material, and let it cure through winter. The oil penetrates the wood grain and slows drying and checking (surface cracking) that occurs from repeated wet-dry cycles.
Cost Comparison: DIY vs. Store-Bought Trellises
A pre-made cedar trellis from Gardener's Supply Company costs $50 to $90 for a 4x6-foot panel. A wire grid trellis from Home Depot costs $25 to $40. The DIY wire mesh panel trellis in Design 1 costs $35 to $45 and is substantially stronger than any store-bought option because it uses 2x2 cedar uprights instead of the 1x1 or 3/4-inch square stock used in commercial trellises. The DIY A-frame costs $25 to $35, compared to $60 to $100 for a pre-made A-frame. The DIY string trellis costs $12 to $18, compared to $20 to $30 for a store-bought string trellis kit.
The strength difference matters most for heavy climbers. A mature indeterminate tomato plant loaded with fruit weighs 30 to 50 pounds. A commercial 1x1 cedar trellis bows under this weight and may snap at the joints. A DIY 2x2 cedar frame handles 50 pounds per panel without visible deflection. For light climbers like peas and beans, the commercial options are adequate and save you the building time if you are willing to pay the premium.