4 Easy Ways to Stake Your Dahlias So They Don’t Flop Over

With their large, heavy flowers, dahlias are the divas of the flower garden. After you’ve gone to the effort of planting and caring for your dahlias, the last thing you want is for a rainstorm or even a critter (chipmunks sometimes climb dahlia stems to take a look around) to break stems or flop them over. Here’s what you need to know about staking dahlias to keep them looking their best.

Why to Stake Dahlias

Dahlias have hollow stems, which are prone to breakage in strong winds or rain. The larger their blooms, the more likely they are to flop. Smaller blooms are easily held up even on long stems, but large and giant types of dahlias reaching eight to 10 inches in diameter get heavy and droop, especially after a rain. Candidates for staking include dinnerplate dahlias, which have enormous flowers of 12 inches or more in diameter.

Staking dahlias also keeps them out of the way, allowing you to walk by easily without wading through foliage and stems, and prevents them from collapsing over and shading other plants. These gorgeous plants are much more impressive when kept vertical instead of hanging sloppily all over the garden. And, if you grow taller varieties, which grow up to six feet, keeping them well-supported will allow you to appreciate their full height.

While dahlias work great as the thriller in a traditional thriller-filler-spiller container planting, taller dahlias require staking to prevent the plant from leaning to one side or, if the heavy blooms get wet, cause the pot to topple over. Supporting potted dahlias keeps the container tidy and stable.

Which Dahlias Need Extra Support

Many dahlia varieties grow three feet tall or more, and that’s about the plant size where staking becomes a good idea. However, shorter bedding types and smaller varieties often don’t need staking, especially in protected areas. Medium-height dahlias with compact blooms might not need staking, but it’s a good idea to have at least some support in place to prevent any issues in the late summer when dahlias are heavily blooming.

When to Stake Dahlias

The best time to stake dahlias depends on the type of support. Individual stakes for each plant should be installed before planting your dahlias to avoid spearing the tubers. Support that is not close to the plants can be placed later when the plants are already growing

Regardless of the method, the key is to have the support ready before it’s needed. If you’ve ever struggled to fit wire tomato cages over plants that should have been staked weeks ago (but you forgot or didn’t get to it), you understand it’s much easier, and better for the plants, to have it ready when they’re young.

Methods for Staking Dahlias

However you choose to stake your dahlias, make sure that the material you use is sturdy enough to support their weight and keep them upright in the wind. Tomato or wire cages are a one-and-done solution, but for other methods, you’ll need to apply a new layer of twine or other material a few times during the summer as the plants grow.

1. Posts and Twine

For dahlias in rows, using posts and twine might be the most common method because it is inexpensive, fast, and works reliably. You’ll need some fence posts, typically T-posts or other metal posts for fencing, a suitable driving tool, and twine. 

If there is a farm supply store near you, buy the twine in a large roll meant for baling hay. It will be enough for years of dahlia staking and other garden chores, and is much less expensive than buying jute or twine in smaller amounts. Natural colored twine blends in quite well with the foliage, mulch, and flowers. Place the entire roll in a bucket and pull from the center. Then, carry the bucket with you as you go.

How many posts you’ll need depends on the length of your row. Place two metal posts at each end and several down each side of the bed about 15 to 20 feet apart. Wooden or bamboo stakes need to be closer together.

• Install the posts or stakes firmly.
• Beginning about 12 to 15 inches above ground, tie off the twine on a corner post and then run it to each post in succession, looping around the post and moving on. Keep the twine tight, but not so tight that you bend the posts. Tie it off at the post you started with. Repeat about 10 inches higher as needed throughout the season. 
• Alternatively, some people prefer to weave the twine from side to side in a crisscross pattern for internal support. 
• If you use quick-release knots, you’ll be able to reuse the twine for several seasons.

2. Tomato Cages

Large tomato cages work well for individual dahlia plants, provided you can secure them deeply in the ground. Either galvanized or green vinyl-coated cages work fine. For larger dahlia varieties, opt for the heaviest-duty cages available. They’ll last longer and be more up to the task of supporting a 5-foot-tall dahlia.

You’ll need one tomato cage per plant. If you have many dahlias, the expense and storage of the cages during the off-season may become an issue.

• Plant the dahlia tubers as you usually would.
• Once you see about 1 to 2 inches of growth, place the tomato cage so the sprout is right in the center. Drive the metal ends of the cage into the ground as deeply as possible. Make sure to wait for the dahlias to poke up because a dahlia tuber doesn’t always sprout in a predictable spot.

3. Individual Stakes or Sticks

Many gardeners plant dahlias as single plants, letting them be the stars of the show in a flower bed or a large container. Single bamboo stakes, wooden tomato sticks, or even trimmed tree branches all work well (as do single metal posts). You’ll still need some twine to tie around the plant and back to the post at intervals, similar to the method for posts and twine in rows described above.

• Drive the post or stake into the ground before planting the tubers or transplants.
• Plant the dahlias so the sprouting eye is about a hand’s width from the stake.
• As the plants grow, tie them to the stake, starting about 12 to 15 inches from the ground. Retie them about every 10 to 12 inches as they grow.

4. Netting

Horizontal netting secured by posts is another way to support dahlias. Sold as trellis or cut flower netting by garden supply stores, it has 4- or 6-inch square holes for the plants to grow through. This method is fast to install; however, in autumn, separating the plants from the netting is cumbersome.

• Pound sturdy metal posts at the end of the rows and partway down each side.
• Once the dahlias are a few inches tall, install the netting. It is virtually impossible to install once they’ve grown taller and need to be individually poked through the holes.
• Stretch the netting tight between posts and secure it to each post with plastic ties or twine.

Of course, you can get creative and use anything from homemade sculpture-style supports to old copper pipes from a junkyard, which weathers to a lovely patina. The important part is to have the netting in place before the plants grow large, and ensure that the posts are sturdy enough to handle the job.