“My butterfly bush was so rangy last year. How can I get it to be fuller and to attract more butterflies?” Question from Diane of Newark, Ohio
Answer: Several things can cause butterfly bushes (Buddleia davidii, USDA Hardiness Zones 5-9) can have flowering and vigor troubles. Here are the main culprets.
Age: If your butterfly bush is an older specimen, it may be petering out. They are not the longest-lived shrubs, and as they age they often show less vigor and flowering. Many may only thrive for 10 or 20 years, or less. If it’s time to replant, I recommend that you try Proven Winner’s Lo & Behold®‘Blue Chip’ butterfly bush. It’s sterile, so it does not become invasive, and it blooms nonstop all summer with wands of purplish-blue that draw lots of butterflies. It is also more compact, at 2.5 to 3 feet high. (Click here to discover more sterile varieties.)
Light: Make sure your plants get full sun. Less light puts a damper on flowering.
Soil: Well-drained average soil is best for butterfly bushes. If your soil has drainage issues or is heavy, then you may need to move or replace your plant.
Pests: Various pests can reduce the vigor and flowering of butterfly bush. Tackling them early will help your plants perform better. (Click here to learn more about common pests.) Fortunately, butterfly bushes have few disease problems.
“I just moved into a new house and will be removing a butterfly bush. How much of the root ball do I need to remove so it doesn’t come back?” Question from MaryAnn of Portland, Oregon
Answer: Though beautiful, standard butterfly bush (Buddleiadavidii) tend to be very weedy and invasive, which is why gardeners often remove it. Remove the whole root system to make sure that it does not come back. The process will require sharp hand pruners or loppers, good garden gloves, and a sharp, heavy spade. Cut back all of the top growth, so you don’t have branches in the way when you start digging. Then dig deeply around the rootball, and pull it up when it’s fully loose. It should not be too difficult. Butterfly bushes don’t have very dense, deep root systems, so they are fairly easy to remove. Let me know if you want any ideas for replacements!
“What is the care for a butterfly bush in the spring? Mine is pretty old, and I always trim it back in the spring, but it isn’t yielding as many blossoms.” Question from Diane of Newark, Ohio
Answer: Start by pruning your shrub, if you didn’t the previous fall. I recommend that you wait until after the last frost of spring to prune buddleia back. When you do, hard-prune it back to 1-foot high. Buddleija should grow back quickly once the weather becomes warm, so don’t worry about cutting it back so severely. To encourage the best possible flowering, feed your shrub with bloom-boosting plant fertilizer (Proven Winners® Control-Release Fertilizer is a good choice).
If your shrub is old, you may opt for another tactic. Butterfly bushes often don’t live past 20 years, and some of the newer varieties can have even shorter lifespans. So, if your shrub has begun to lose gusto, consider planting a new one. Some of the best new varieties are available through Proven Winners. We recommend those in the Lo & Behold® and Miss series because they’re seedless and non-invasive, unlike other common varieties. When planting any new shrub, amend the planting soil with Black Gold® Garden Compost Blend to help it establish roots quickly.
“When is the best time to prune Buddleia?” Question from Angie of Fort Bragg, California
Answer: In your coastal Mendocino County location, I would cut your butterfly bush (Buddleia spp.) back when your cool, wet winter hits. Butterfly bush does not look its best when chillier temperatures hit, even though it remains evergreen to semi-evergreen where you live, so prune it back by 1-2 feet once it stops blooming well, and its leaves start to flag. This will also make your garden look tidier during the chillier months and result in a more compact shrub. And, because it blooms on new wood and grows post-pruning quickly, you can feel confident that the shrub and flower buds will not be harmed.
Another factor is that butterfly bush self-sows prolifically and is considered invasive in your area. Pruning it back and removing its old buds before seedset will also reduce the chance of spread in your garden and beyond.
“What’s the best way to care for my butterfly bush, now that all the flowers are gone? I usually cut it all the way back in the spring, which usually makes for a beautiful bush throughout the summer. This year, not so much. It was not very full, although it did grow quite tall. Should I be doing something to it in the fall?” Question from Diane of Newark, Ohio
Answer: If you trim the seed heads off of your butterfly bush (Buddleia hybrid) now, you may get a new flush of flowers before season’s end, if the weather stays moderately warm. So, don’t give up on your shrub so early. There are lots of migrating monarchs that still need food for their travels.
Butterfly Bush Pruning Time
There are different fields of thought regarding buddleia pruning time. Some say late spring; others say it does not matter. In my experience, when you hard-prune it back (I generally prune mine back to 1 foot) depends on your hardiness zone. I have pruned mine back in both spring and fall with no difference in summer performance, but my USDA Hardiness Zone 7 garden is milder than yours. So, for your Zone 6 garden, I recommend that you wait until after the last frost of spring to prune buddleia back.
Butterfly Bush Fertilization
For top flowering performance, I recommend that you feed your shrub with bloom-boosting plant food. It should also get full sun for most of the day. Butterfly bushes often don’t live past 20 years, and some of the newer varieties can be shorter-lived. This must also be taken into consideration.