Looking to grow tomatoes vertically in your garden this year? Or maybe just realized you need a stronger tomato trellis? In this post, we’ll cover how the tools, materials, and step-by-step process to build this strong DIY tomato trellis.
If you’ve ever grown indeterminate tomatoes, then you know they can get heavy and need some support. We’ve personally tried several different methods to support our tomato plants: traditional wire cage, horizontal Flordia weave using strings, and plenty love and encouragement. You got this tomatoes! But we’ve found that the best way to support them for us is with vertical lines to an overhead beam.
We tried this method last year and it worked really well, but it also came with a few issues. Namely, we didn’t make the beams tall enough or strong enough. Did we mention how heavy the tomato plants can get? So this time, not only did we build a new overhead beam, we OVER-built this beam. It’s so strong that our toddler can (and will, if we’re being honest…) use this as a jungle gym!
In this post, we’ll cover how the tools, materials, and step-by-step process to build this strong DIY tomato trellis.
Tools & Materials For A Tomato Trellis
Since we wanted it to be a feature piece as our terraced vegetable garden is in the front yard. The tomato trellis is designed to simply slot together using castle joints with decorative chamfered ends. This means it requires more intermediate to advanced woodworking skills. Yes, it’s a little extra, but it gives it a high-quality final look elevating the garden space.
- Tape Measure
- Framing Square
- Miter Saw
- SawStop Table Saw
- Trim Router (optional)
- Plunge Router
- Template Bit
- 1/8″ Round Over Bit
- Random Orbital Sander
- 3M Xtract Cubitron II Sandpaper
- 4×4 Cedar Posts
- 2×4 Cedar Boards
- Rubio Monocoat Wood Cream – Snow White
- 4” Exterior-rated Screws
- Post Ground Spike
Tomato Trellis Build Process
Step 1: Make A Plan!
DIY work is about figuring it out and making it yourself, but it’s best to always do some planning before diving in. We love to make it easier for other DIYers and since everyone’s build is unique to their garden, we created a customizable set of DIY plans. These plans ask you to measure your space to determine your desired final dimensions and then walk you through the math to customize your plan set to fit your needs. You can find these custom plans in both our Site Shop and Etsy Shop.
Step 2: Get The Materials
Since this tomato trellis is going to be outside, and you want it to hold up for many growing seasons, you’ll want to build it out of rot-resistant Cedar. Cedar is a pretty soft wood, but it holds up in exterior environments well, can be finished to prolong its life further, and is commonly available at both hardwood dealers and big box home improvement stores.
Depending on the size you choose to build the trellis, the number of posts and boards will vary. Our plans set will help you to put together a custom materials list for your build. Keep in mind, if some of the posts and boards are short enough, you may be able to save some money by buying a longer post and cutting it in half.
As for finishing, there are a ton of exterior finishes out there. However, we tried out a new exterior finish for this project: Rubio Monocoat’s WoodCream. This is different from their Hybrid Wood Protector we tried on our Planter Box build last month.
Full disclosure: Rubio gifted us the WoodCream to try on this project and this post isn’t sponsored. You will always get our honest opinion, and we’ll have a product review article later.
Step 3: Evaluate The Boards
Once you have the boards, you may be excited to start your project, but it is important to let the boards acclimate first. In our case, we bought these boards from Menards who keeps them in an open-air warehouse. It was also raining the day we collected the wood and it looked like the bin had been recently replaced. The boards felt quite cool to the touch and some were almost damp, so we spaced them out and gave them a few extra days to dry out before beginning our project.
Once the boards have acclimated, evaluate them for any warpage that may have occurred and then plan the cuts accordingly. For us, there were a few boards that warped at one end and we were able to cut most of that warp out and make them into the shorter boards. Since we are applying a semi-solid finish, we aren’t as concerned with grain matching or appearance here as we would normally be for a furniture project.
Step 4: Cut The Boards To Length
Once you have all the cuts planned out, bring the boards and posts over to a miter saw and cut them all to length. Make sure you are trimming off both ends so that you have a good cut edge on both sides of the boards.
When cutting the posts, consider installing a block between the post and the miter saw’s fence. With as thick as the posts are, most miter saw blades aren’t able to get all the way through the board at the end of its stroke. This block board pushes the post further forward and lets you utilize more of the blade.
Step 5: Add Chamfered Ends
Once all of the boards are cut to length, it’s time to add some aesthetic chamfers to the ends. Turn the miter saw to 45 degrees and lock it down. Due to how this is being cut, it is difficult to set up a stop block to make this cut repeatable. Luckily, these cuts are just decorative and they don’t have to be exact. So you can mark each cut using a trusty speed square. Then bring the boards over to the miter saw, line up the blade with the mark, and make the cut.
Step 6: Cut The Half Lap Joints
Next, it’s time to cut the half lap joints for the beams of the trellis. You could do these half laps with a router or with chisels, or even with an oscillating multitool or jigsaw like we did for our Canopy Bed build. But whenever possible, I prefer to do these on the table saw. I find this faster than using the router, it’s extremely repeatable, and I can use an offcut to set the width of the cut and get a good fit. Here’s how it works on a table saw.
Cutting Half Lap Joints On Table Saw
First and foremost, it helps to have a cross-cut sled and side support table to support and control these longer boards. You can do this same process with a miter gauge, but I certainly feel safer having a cross-cut sled.
- Start by marking out where the half lap will be on the first board.
- Then line up the blade with the edge of this line and clamp the board down to the sled.
- Next, bring over the stop block to set this position.
- Now, here’s the trick. If you were to just put your stop block against the piece, then you would have a consistent starting point, but if you tried to use an offcut to set your end point, you’d end up with your half lap being one blade width too large. So instead, put a blade width gap between the edge of the piece and the stop block.
- Since most blades are ⅛” thick, you can use an ⅛” drill bit as a setup block. Just place that between the stop block and your board and then clock your stop block down.
- Turn on the saw and push your sled forward to make that first cut.
- Then we undo the clamps and slide the board to the left.
- Now, if you put an offcut piece between the board and the stop block, you will be at the perfect endpoint for the cut.
- Push your sled forward again to make this cut and you’ll now have your start and end cuts set.
- All that’s left to do now is slowly advance your board back to the right and make multiple passes to remove the material between your two cuts.
HUBBY TIP: Keep in mind that if you are using a Thin-Kerf blade, then your blade won’t actually be ⅛”. So you’ll need to either use a smaller drill bit or spacer, or come back with a final pass to widen your slot slightly.
This part of the process would go faster with a dado stack, but once you get the hang of it, it still goes quick. Simply repeat this process for all of the boards and you’ll have your half laps done in no time.
Half Lap Splice For Extra Long Trellis
As a final note, if you are making your trellis longer than a single board length as we did, then you’ll need a way to join those two boards together to make one longer board. To do this, use this same setup to create a half lap splice. This is even simpler since you can just set your stop block and then cut all the way to the end of the board without needing to use an offcut or drill bit to set your positions. Just make sure you position the joint on the correct side of the boards so the pieces join up when you’re done.
If you have a flat ground tooth saw blade, then your cuts will already be pretty clean, otherwise you will need to come back with a chisel and clean up the cut to flatten it out. Once it’s flattened out, go ahead and glue the half lap boards together with an exterior-rated wood glue. It’s better to do this now than after sanding so that the cuts stay true and you don’t end up with any misalignment or thickness variations that you’ll have to sand out.
Step 7: Cut The Castle Joints
To install the half-lapped boards onto the posts, the trellis design uses castle joints. We did these on our Canopy Bed build as well and primarily used the oscillating multi-tool for them. That worked well enough, but it was hard to be consistent and they required a fair bit of clean-up at the end to get a good fit. We’ve learned to use a router since then and that made this process significantly more repeatable and much faster.
Make Template For Router
To start, make a template to support and create edges for the router. To do this, cut a scrap of plywood to be the same width as an off-cut board. Now, position this scrap between two more pieces of plywood and check its fit. Once you’ve dialed in this fit, glue these pieces together.
We originally tried to do this with wood glue, but that didn’t work so well. We were gluing end grain to end grain, and the plywood scrap had previously been sealed with boiled linseed oil. So the glue joint broke apart almost immediately… Next up we tried super glue. We spread a bead on one piece of wood, sprayed the other with an accelerator and then pressed them together. They took seconds to set up and produced a much stronger joint!
Cut Joints Using Router
With the template made, it’s time to start making the castle joints. Position the template so that the top edge is aligned with the edge of the post and then center the template on the post. Clamp it in place. To make this process faster and more repeatable, we then glued two more scrap pieces of plywood on the underside of the template to hold it tight against the post.
Now, take the router with a templating bit and run it around the template to remove the first pass of material. Then repeat this process on all four sides of the post on every single post to complete the first depth.
For the next depth, remove the template which drops the bit ¼” deeper. Then use the wall from the first pass as the new template to cut and run the router around once again to remove material to the second depth. Repeat this process on all four sides of every post.
Now that you have a slot cut that is a good depth, you can really start to hog out material. Next, lower the trim router deeper and use it to cut a deeper pass in the slot, then switch over to the plunge router. We have a longer template bit in our plunge router, so we had to get deep enough that we could engage its bearing. But once we were there, we could make pass after pass and easily plunge to the next depth on each side of the post until all that was left is a small amount of material in the center of the post.
All that’s left to do now is cut off that last little bit of material using the longer templating bit, and you have a complete castle joint. Then just repeat this process for the rest of the posts, and the joinery is complete! This was so much faster than when we did the canopy bed. It’s amazing what a difference a year’s worth of experience and a new tool or two can make!
At this point, your castle joint has rounded corners. If you plan to put the same size radius on your trellis boards, then you can stop here. Otherwise, you will want to come back with a chisel and square up those corners.
Step 8: Sand The Wood
With the joinery done, it’s time to get sanding. Our cedar posts are pretty solid, but the boards have a lot of roughness that needs to be cleaned up. Luckily, the 3M Xtract Sandpaper we use makes this much faster. We just toss some of that on our random orbit sander and get to work.
Start with 80 grit on all the wood to remove larger imperfections and then repeat using 120 grit sandpaper.
It’s still a time-consuming process, but getting the boards smooth will prevent splinters, require less finish, and increase the longevity of the wood, so it is well worth the time investment now. Just get yourself a pair of bluetooth shop headphones, turn on some music, podcast, or audio book, and work your way through the boards.
Step 9: Do A Dry Test Fit & Label Joints
Once you have the boards sanded, you’ll want to make sure to do a dry fit of all of the joints. If you need to sand away some more material to make them fit better, then now is the time to do it before finishing! We love using a rasp to make quick, easy work on removing material and not having to break out the hand sandpaper.
After you have it all test fitted, then you’ll want to label the pieces to ensure the tomato trellis goes together easily later. We’ve found that labeling each corresponding joint with a number using a sharpie in the joint is the easiest. Typically, you can see the ink through the finish and it’s hidden in the joint, so you’ll never see it otherwise.
Step 10: Add The Roundovers (Optional)
Once every board is sanded to 120 grit, you can add roundovers to the edges to soften the edges and give the trellis a high-quality look. This isn’t a required step, but if you don’t have a router, you can still round over all of the edges with some hand sanding to knock all the corners down. It won’t be as consistent but it will still keep the boards from producing splinters and having sharp edges.
Don’t do roundovers before sanding as the 80 and 120 grit passes would wear away at the edges and you’d no longer have a nice, tangent transition.
Slot your preferred roundover bit into the trim router and quickly run it around each board. We personally love to use the ⅛” round over on items like this. It’s barely noticeable, but it makes the pieces feel so much better while still giving you the appearance of a sharp edge.
Step 11: Sand to 180 Grit (Optional)
Once the roundovers are done, you have a decision to make. You can stop here or you can go ahead and sand up to 180 grit. Since we used a solid finish (Rubio’s WoodCream), we didn’t necessarily need to go to a higher grit as the instructions only say to prepare the surface to your desired finish.
The 3M Xtract sandpaper does a remarkable job, and 120 grit feels as smooth and soft as 180 grit would with other sandpapers, so we are already happy with the way they feel. And since we spent extra time dialing in the depth on our roundover bit, we didn’t have lines that needed to be cleaned up. We also remembered that this isn’t a piece of furniture and it’s going to be outside, so we decided to prioritize our time and stop at 120 grit.
Step 12: Apply Rubio WoodCream Finish
Next step is finishing the wood to protect it from the elements and increase its longevity. We used Rubio’s WoodCream in a Snow White color for our DIY tomato trellis.
Rubio Application Recommendations
Rubio’s WoodCream is only meant for vertical exterior surfaces, and goes on quite differently than its other products. This starts with prepwork. As mentioned earlier, Rubio doesn’t have a specification for how finely to sand the wood. They only say to prepare the surface to your desired finish. It doesn’t matter whether that is planed, sanded, wire brushed, or something else.
For us, that is 120 grit, but you could have stopped at 80 or gone up to 180, depending on if you are happy with the way those feel. However, you may find that you use more product if you stop at a lower grit as there are more grooves and pores to soak up the finish.
The WoodCream also doesn’t require you to use a wood cleaner unless the piece is oily or has mildew stains. The only requirement is that the piece is dry and clean. Rubio recommends applying this finish in an area that is 50-80°F (10-30°C). And they recommend you don’t apply it in direct sunlight so that it doesn’t dry out too fast and has time to be absorbed by the wood.
With those requirements met, you can get started. Start by stirring the WoodCream and then brush it evenly onto the piece. It’s best to keep a wet edge as you spread it out. Rubio then recommends you come back with a single pass to spread and even out the WoodCream. You can apply a second layer 3 hours later if you want a more opaque look, but we only used one layer for our project.
The product will be dry to the touch in 30 minutes and fully dry in about 12 hours. And that’s it. It’s just as easy as painting, but so much better looking as you can see the wood grain!
Step 13: Assemble The Tomato Trellis
Once the pieces are all dry, it’s time for assembly! Since the tomato trellis is made with wood joinery, assembly goes very quickly. However, it is easier with at least two sets of hands.
We originally thought we could just set the trellis on stones to keep the wood off the soil. But after constructing it, we’d recommend using some form of in-ground anchors to ensure the trellis won’t move or wobble. We used these post ground spikes that have 18″ spikes that go into the ground and 6″ to clamp to the post above ground. There were a lot of post anchors out there, but they weren’t very long. The hubby engineer wanted to ensure these Midwest winds and strong tomato plants wouldn’t pull the anchors out of the ground, so we went with longer ones.
To install the anchors, first, start by measuring out the post anchor distances based on your trellis dimensions. To ensure all the posts are aligned, we created a plumb line using two clamps and string by attaching it to the sides of the raised beds. With the locations determined, we used a scrap offcut piece of a post to hammer the post anchors into the soil. This ensures you don’t accidentally damage the finish or metal on the anchor. Then it’s time to bring over the post and cross boards to begin assembling.
Assembling Posts & Cross Beams
For us, we started by installing the lower tier of our trellis since our garden is terraced. While one person holds the posts, we drop in the first cross board. Then bring over two posts for the upper tier and have someone hold those two and drop in another cross board.
Next, we connect the two tiers with another cross board. Once that board is in place, the structure will largely stand by itself so we can quickly drop in the rest of the posts and boards and get everything situated. If you test fit all of your joints earlier, then you shouldn’t have any issues with this going together now, but feel free to break out a rubber mallet for a little gentle persuasion if you need to. Then tighten the post anchors bolts once everything is in place.
Although the trellis’s joinery holds it together quite well, we opted to add screws into the joints at the top to give it some more rigidity and withstand the Midwest’s strong winds. Pre-drill holes through the top of the joints down into the post. Then use 4” exterior-rated screws to join the pieces all together.
Step 14: Add Strings For The Tomatoes
The final step is to add drop strings for the tomatoes. We simply tie some twine to our cross board above the tomato plants’ location and then run it down to a spike in the ground next to the tomato plant. As the plant grows, you use small pieces of twine to tie the limbs to this string and support the indeterminate tomato plant. TADA! Your DIY tomato trellis is done!
More DIY Projects
Now that you’ve got a sturdy tomato trellis to grow veggies on, there are more DIY and homesteading activities to do, right!? Check out more of our DIY projects and gardening/homesteading articles for inspiration!
- Terraced Garden Beds After One Year – Words of Advice
- Hubby How To: DIY Planter Box
- Hubby How To: DIY Stacked Rain Barrel System
- 15 Awesome DIY Projects At Home You Can Do
- Down To Earth Tips For Eco-friendly Lawn Care
Hope you love building this DIY tomato trellis and you have an abundant harvest from your garden! Let us know what DIY questions you have in the comments below!
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