The butterfly bush (Buddleja davidii) can be invasive in some areas of the U.S.A. Mainly in the Pacific Northwest, where this ornamental shrub finds the best climate conditions. So, given that this plant is hardy to USDA zone 5, one may want to prune it to keep it under control and enjoy its lilac flowers and the butterflies they attract.
When to prune butterfly bush in zone 7? The butterfly bush is renowned for its ability to put on new growth every year. So, you may want to prune the plant to control its size. In zone 7a, you might not need to trim this plant because the elements usually freeze and break most of the new branches. But in zone 7b, pruning the shrub in late winter is highly recommendable.
Top Tips For Pruning A Butterfly Bush In Zone 7 In Late Winter
- Be sure to prune them every year. Butterfly bushes actually have weak wood down at their bottom. So, pruning helps them stay compact and safe. Otherwise, they can get 6-12 feet tall, and then a storm comes and cracks them open.
- The stems at the bottom are pretty thick. So, you will need a bypass lopper for cutting those low branches. But do not cut too low! Cut above some growth on a side stem. Look for a shoot on the side stems and cut above that.
- Prune the small branches with a hand pruner and leave new shoots to promote growth. More importantly, take away all the cuttings you made. If you leave them lying around on the ground, the dead leaves could attract pests or cause diseases.
- Do not prune shrubs shorter than 15 inches.
- Set a reminder for late January or the first of March on your phone. So, you can trim the stems at the best time of the year for the plant to recover and grow back as soon as spring starts.
When To Prune Butterfly Bush In Zone 7 If You Have A Tall Plant Already
If you do not cut back butterfly bushes every year, the vigorous vegetation can grow like crazy. Maybe, you have one of the fifty Buddleia davidii varieties that copiously produce new growth and flowers. So, when to prune butterfly bush in zone 7 if you already have a 10-12 feel tall plant?
When dealing with a fully developed flowering plant, bringing the stems to five or six feet at first is highly recommendable. Wait until late January for pruning it. In this way, you can check for new growth in the lower stem. Not every woody stem at the bottom could have new shoots.
After the growing season, the new shoots will be more prominent. So, you will find it easier to cut it back even further. You could also remove some of these branches later in summer when deadheading the spent flowers.
Propagating Buddleja Davidii In Zones 7a & 7b
Let’s see when to prune butterfly bush in zone 7 for propagating the plant. First, you need to find at least one 6-inch soft wood candidate. The cutting length should not include the blooms, nor be shorter than 4 inches if no longer stem is available.
Usually, the best time to take cuttings is during summer. If the stem has a bloom, cut the flowers off before proceeding—you will also need four or five cuttings to increase the chances of success. Remove the bottom leaves from the cuttings with a pair of disinfected scissors or pruners.
A few leaves will be more than enough for the cutting to survive and root. Next, get some moist potting soil and a pot with drainage holes. For the best results, use a rooting hormone. But do not stick the cutting too deep into the soil. Half of the cutting should stand above the ground even if you put it in the gardening bed right away.
In gardening terms, keep three nodes into the soil and the remaining ones bearing leaves. Butterfly bush cuttings will take roots in five weeks. So, wait for the 15th of August to propagate your plant if the weather is scorching hot and dry. Mist them and keep them moist to keep their temperature low while providing indirect lighting—never put them under full sun, and they will do just fine!