Plant clippers on hydrangea stem

Pruning: Hydrangeas and Clematis

In Feature, Perennials, Spring by Samantha Karsten

Panicle Hydrangeas: Prune Now

When should hydrangeas be pruned? That’s a common question, and the answer always begins with “it depends.”

Time of pruning depends on the variety of hydrangea. End of March to beginning of April is the perfect time to prune panicle hydrangeas. Given the long winter and late spring this year, hydrangeas are late to leaf out, so now is still a good time to prune panicle types (just get to it before they begin growing leaves). So how do you know if you have a panicle hydrangea?

If you know the name of your hydrangea, it helps. Panicle hydrangeas include: Limelight, Little Lime, Quickfire, Little Quickfire, Strawberry Sundae, Vanilla Strawberry, Fire Light, Bobo, and many, many more.

If the hydrangea in question wasn’t listed here, or you don’t know what kind it is, consider its bloom habit. Panicle hydrangeas typically start white or lime green and turn to pink or red, some color up very quickly, or as is the case with Limelight, very slowly and not until into fall. Panicle style hydrangeas also have stiff stems and a cone shaped flower.

If the hydrangea has big, white mophead flower and is floppy, or has blue or pale pink flowers when it blooms, or if it is a climber or has oak shaped leaves, it is not a panicle and does not want to be pruned right now.

If you’ve determined you have a panicle hydrangea, then now is the time to prune!

Basic Steps

Once the panicle hydrangea is 2-3 years old, begin pruning. Prune back each year by about 30-50% to maintain shape and promote blooms.

Prune just above a set of buds before the plant leafs out. The buds will look like two little bumps across from each other and can be found all along each branch. Panicle hydrangeas bloom on new wood, and new wood growth comes from the last set of buds before the end of the branch. If the shrub is allowed to leaf out and is then pruned, the buds that were supposed to become blooms have been cut off and the shrub won’t bloom. If this happens, don’t worry, the shrub will be fine but you’ll have to wait until next year for blooms.

Make the pruning cut at a 45 degree angle. This allows the water to run off the end of the branch rather than sit on top of it, possibly causing fungus and rot.

Fertilize when new growth begins and wait to enjoy the show!

Clematis: Plan for Pruning

So when should you prune your clematis, and how? It depends. This is another plant that requires identifying what type it is in order to know how to prune it. If the clematis was just planted last year, however, and has just gone through it’s first winter, you’re in luck! This is the easiest year. Prune the clematis back to about one foot above the ground. You’re done for this year. If it’s older than that, read on.

It’s possible you know a clematis that’s rarely, if ever, been pruned but seems to be fine. Usually, however, if left to grow freely clematis will climb as tall as it is able, flower mostly at the tops of the vines, and for varieties that can become very tall it may become top heavy. Pruning also encourages growth and flowering, and if the vines are thinned it allows more air circulation and helps fight fungal problems.

There are three different pruning categories, or groups, for clematis. If you’re not sure what type of clematis you have, go ahead and let it go for another year. Determine and record when it blooms so pruning can begin the following year. If you can determine which group the clematis is in, consider these pruning options:

Group one flowers early on last year’s growth. Prune immediately after flowering. The new growth after pruning will produce flowers for the next year.

Group two are rebloomers, flowering first in late spring or summer and then again later. The easiest way to prune this group is by cutting it back hard every few years in late winter/early spring, before it begins to leaf out. This will affect early blooms only in the year it’s cut. Another approach is to thin the stems before growth begin in spring, and then prune the stems that bloomed when they’ve finished (leaving alone those that didn’t). This is a more time-consuming option, but is less harsh than a hard cut and will stunt fewer blooms.

Group three flowers in late summer or fall. In spring, just as buds are beginning to form, prune back to just above a set of good looking buds, about one foot above the ground. That’s it!

For information on pruning groups for specific varieties, visit Donahues Clematis Specialist pruning guide.