The first question when you start to grow your goods up is: Why trellis garden plants in the first place? Well, there are four reasons.
1. Space
Trellising garden plants lets you grow horizontally and vertically, allowing you to grow far more food in far less space.
2. Synergy
The well-known “three sisters” planting practice of Native Americans—combining corn, beans and squash—was a trellised system. The beans climb the corn. This lets the plants work together to each other’s benefit.
Trellising allows you to then take advantage of the space below trellised crops to sneak in additional stuff that will enjoy the shade created by the trellis crop.
Our trellis garden plants almost never occur alone. And we often get two or three other plantings below and around these slower, taller, longer growing plants.
3. Reduced Strain
Let’s face it. None of us are getting any younger! But bending down and over and getting on our hands and knees isn’t something that can easily be avoided.
However, if you are growing a great deal of food, it isn’t bad to reduce. Trellising moves plants up closer to where you naturally are, and cuts back on some farmer or gardener wear and tear.
4. Sickness
Moving plants off the ground reduces issues with pests and disease. The lack of direct ground contact with the soil for almost all the plant means soil-borne pathogens can only access the plant through the root system, greatly reducing exposure.
Ground-based pests also now have only one access point to attack the plant. 
You Have Trellising Options
Trellising is scale-specific. What works well on a smaller scale—say a dozen or so plants—may not be appropriate or sensible for many dozens to hundreds.
Cages were our first trellising system. It’s one that even some midsized farmers we are friends with used for many years. You can make your own cages out a number of materials, such as welded wire, concrete reinforcing wire (CRW) and many other materials.
No matter what size wire you go with, make sure the holes are large enough to easily harvest the crop through! Nothing will annoy you more than realizing your peppers or tomatoes (or hands) are too large for the spacing the wire creates to access what is inside the cage.
When we made our cages, we used CRW. We made most of them self-staking by cutting off the bottom rim, while leaving all the vertical wire points. This created roughly 6-inch-long stakes along the bottom (every 6 inches) for securing the cage.
These stakes provided the significant support that light- and medium-weight plants—such as cucumbers, beans, peas, etc—usually require.
For larger, really leafy plants, it helped but was insufficient alone. This included tomatoes and peppers.
Read more: Try the Florida weave trellising system for healthy tomatoes! This video shows you how.
Cages Work Fine
Cages often still require some additional support, at the ground and for the plant inside the cage. The looser your soil is, the windier your area is. And the heavier the rains are, the more you’ll want to reinforce or stake.
There are a number of ways to do this. You can purchase premade stakes or make your own by bending spare wire, rebar or similar material. How big and deep your stakes should be depends on how loose your soil is and how large and heavy your plants are.
Looser soil and larger, heavier plants require more, deeper and larger stakes.
You’ll still need clips or twine to train your plants to the cage (or to keep them centered and anchored) for peppers and other larger plants.
How to Run Your Lines
One of the most common methods of trellising in the garden, especially for raspberries and similar plants, is horizontal lines between posts and end posts. You can also use this method for other plants (outside berry crops), such as tomatoes.
For plants that grow a single main stock, single leader (vertical) lines suspended from above on pipes or supports can work well.
We like this method for peppers in our high tunnel, where wind isn’t an issue. But such an approach was a bust in the field. The peppers needed more protection and support because of strong winds or storms passing through our area. 
Why You Should Try Horticultural Netting
This past year, as we have continued to expand the amount we grow, we decided to skip making more cages and try horticultural netting. For vining crops, especially cucumbers and cherry tomatoes, this stuff impresses.
Relatively easy to set up and work with, along with fairly durable, it made harvest easy, plants healthy and my son quite successful in his cherry tomato business.
We used 8-foot T-posts with PVC Ts to hold the crossbars (extra purlins I had ordered to go with our tunnel or EMT conduit). The netting we hung by threading the pipe through it. We also provided additional support by using reusable zip ties to further secure the netting every few feet to the pipe.
I had hoped to reuse the zip ties, but we learned that the immense heat they were exposed to in the tunnel on the metal pipes turned them into one-season wonders. You could also use good rope or twine to secure the netting to the cross bars instead.
Make Sure Your Spacing Is Right
Whatever you do, just be sure that your T-post spacing, pipe and ties are sufficient for the weight of the crops they’ll need to support. Once a crop is established, it’s difficult to add more support.
Our T-posts were on 12-foot centers for the purlins and 8 for the conduit. This was the length of the purlins, and their strength was sufficient for that space.
The setup did well for cherry tomatoes, even with my son’s neglect of sufficient pruning. The netting did snag, but the pipes and setup otherwise performed superbly all season long under the growing weight.
If you are using weaker pipe, you’ll need to use more T-posts spaced closer together. Another option in a high tunnel or similar structure is to provide additional support from above. Anchor the crossbars to purlins or other parts of the tunnel’s superstructure using rope to distribute the weight.
Read more: You can grow pumpkins vertically, too! Here are some tips.
How to Trellis Those Nontraditional Garden Plants
If you’re really short on space, you can trellis certain garden plants that you may have never considered as candidates for such an approach. For instance, we have trellised sweet potatoes vertically up as well as vertically down.
We’ve gone over the sides of balconies, porches and similar landscape features.
This let us grow triple the number of plants in the same amount of space with about a 20 percent loss in yield per plant. So overall, we saw a net gain. It creates extra work, sure. But if you’re really tight on space, it’s something you may want to consider.
Melons and winter squash are usually not trellised but can be. You want to make sure you are working with smaller and, thus, lighter varieties.
Also, if space isn’t a consideration, a few labor intensive trellising crops, such as cucumbers, don’t have to climb to the sky! We know a number of growers who mulch cucumber beds with straw or similar material, transplant and let them sprawl along the bed.
This saves big on labor. And the mulch reduces ground contact for reducing disease. It works just fine—even if it takes more space.
Sidebar: Use Cattle Panels!
Cattle panels are just one of those oh-so-useful items to always have around. They make for a great trellis for garden plants such as pole beans, snow peas, tomatoes, peppers in rows (with panels on both sides or on a single side) and more.
You can use them for vertical trellis or bend the panels into arches or similar structures. This creates a lovely microclimate under the arch once the trellised crop is established.
Lettuce, spinach and other greens that can do well with dappled sunlight and cooler temperatures work well under the arch.
