Pruning gorgeous flowers is complex
There are few plants that rival the bloom display of Clematis. These glorious blooms are usually big, bold, and if the plant is healthy, they cover the entire plant.
Each year I get several questions regarding pruning Clematis. Unfortunately it gets a little complicated since there are several different varieties of Clematis, each with different bloom times.
Clematis are divided into three groups based on their bloom time and then pruned accordingly. Group 1 includes the early flowering types that bloom in late May and early June. The flowers bloom on old wood or the wood that developed last year.
Clematis in group 1 should be pruned after they finish blooming. Don’t make the mistake of pruning them in the fall or early spring as you will cut off any of the flower buds that have formed this summer.
The varieties found in group 2 bloom on old wood that was developed last season but then they also bloom again on new wood that grows during this season. If you have these Clematis, they are likely showing color right now.
The second flush of blooms that comes on the new wood isn’t usually as full as the first, but it’s still great and gives you color in the garden.
The key to pruning these is to do it lightly as they don’t need much. Lightly prune branches and dead flowers after the first flush of growth in the spring and then again lightly prune after the second flush of growth.
The only reason I might prune group 2 is that if they become straggly or out of control.
Varieties of Clematis in group 3 bloom in the latter part of the season on new wood that is formed during the current growing season. These typically are considered the fall-blooming Clematis and flowers show up in late August and early September.
These can be pruned in the very early spring or even late this fall after blooming. They flower on new growth, so you can cut them back pretty far and still have a nice plant.
If they are overgrown, they can be cut back by more than half and still put on a spectacular display.
The other question that is related to pruning Clematis has to do with pruning Hydrangeas. Here again, it depends on what variety of Hydrangea you have.
Some bloom on old wood that developed last year (oakleaf ) and some bloom on new wood that grows this season (Limelight, Vanilla Strawberry).
The rule of thumb is that if a plant blooms on old wood, prune after blooming; if it blooms on new wood, you can prune in the early spring before new growth begins.
No matter what type of pruning method you favor — vase, open air, summer, winter — the first step is to have the right tools.
Contra Costa Master Gardener Keith Silva says using the correct tools makes all the difference when it comes to the healing and health of the plants you prune. Here are some of Silva’s do’s and don’ts:
When removing limbs, never cut off the collar. The collar is the swollen area where the branch comes out of the main trunk. Cut a branch flush with the collar, not the tree. Removing the collar can expose the tree to disease and pests.
The tools
There are two different types of pruners - anvil and bypass. For making cuts into live wood, use bypass pruners. For dead wood, or cutting up pruned branches, use anvil pruners.
Using any sort of pruner crushes the wood as the cut is made. The bypass pruners crush only one side of the wood while the anvil pruner crushes both.
A bypass pruner has an arched blade and a narrower, hooked blade. When making cuts, make sure the side of the pruner with the hooked blade is on the side of the wood that will be removed. Use bypass pruners when making cuts flush with the collar.
Anvil pruners make it easier to cut, and give you a bit more stability with the pruner.
When cutting larger branches, use a lopper, which is like a pruner except that it has long handles for added leverage. Loppers also come in bypass and anvil models.
Sometimes you need a saw. There are special saws for pruning, which are different from saws used in carpentry. Pruning saws cut on the pull stroke while carpentry saws cut on the push stroke. Pruning saws are designed for cutting wood and dealing with sap.
If you have limbs you’ve removed from trees, or branches that you want to cut into smaller pieces or firewood, use a bow saw, which looks a little like a hacksaw but is designed specifically for wood cutting and pruning.
Pole saws are saws on long poles that usually allow you to remain on the ground while reaching higher branches. Silva advises against using them. “If you need to use a pole saw,” Silva says, “you probably should hire a tree service.” Silva dislikes them because the user can’t see where they are cutting, which could create a problem by cutting the branch in a wrong spot.
Beyond the cut
Never seal pruning cuts. In order to heal, the wounds need to dry out and sealers prevent them for doing that.
Sanitize your cutting implements to prevent the spread of disease, especially if you are pruning a tree with fire blight. Create a mixture of 9 parts water to 1 part chlorine bleach. Dip the blades in the solution or keep the mixture in a spray bottle. Spray the blades over a bucket so as not to contaminate the soil.
For general cleaning, isopropyl alcohol can be used, but not if you’re cutting diseased wood.
After using your pruning tools, clean and oil them to prevent rust.
Keep your pruners sharp to enhance cutting. Using a rasp file will likely damage the blade on the pruners. Instead, use a carbide sharpening tool. Sharpen only the curved edge of the main blade - the side without the hook - by matching sharpener to the angle of the cutting edge and scraping away from the pruner. Never try sharpening the flat, back side of the pruner.
Safety first
Be well rested before attempting to prune.
Wear protective goggles. Eye injuries usually come from the side. Wear gloves. Have your cellphone with you and easily accessible if things go wrong.
If you can, avoid ladders. Prune your trees to keep them small and manageable.