How to Plant and Grow Butterfly Bushes
Where will they grow?
Butterfly bushes (Buddleia davidii and related species) are considered hardy – i.e., able to survive the winter – in USDA zones 5, 6, 7, 8, and 9. If you don’t know what your hardiness zone is, you can look it up by your zip code at the USDA website. In colder climates, you can grow and enjoy them as annuals, lasting for the summer only, but they won’t generally survive the winter, and bringing them indoors is typically very stressful for you and for the plant.
Butterfly bushes are full sun plants. That means they should get at least six hours of bright sun each day. It doesn’t need to come all at once – it can be in chunks throughout the day. In very hot climates, a bit of afternoon shade is permissible.
Well-drained soil is crucial for a butterfly bush to survive. In other words, they cannot grow in areas that remain wet for any prolonged period of time. They prefer conditions on the drier side, and can quickly experience severe root rot in wet soils. They do best in sandier soils, but can be grown in clay soil as well, provided there’s no standing water.
When you plant a butterfly bush, you should not add anything to the soil. Do not add potting mix, compost, top soil, garden soil, etc., all of which can cause drainage issues that severely set back, possibly even kill, your plant. Simply plant directly into your natural soil.
If you have clay soil, you should also plant your butterfly bush “high”: in other words, place it in the ground so that the top of the rootball is slightly above, rather than even with, the soil surface. This helps water to drain away from the plant. Our one-quart sizes are perfect for planting in clay soil because you don’t need to dig a very big hole to accommodate them.
Removing the old blooms when they are done flowering is called deadheading. This can be quite a chore on plants that have as many flowers as butterfly bushes do! It’s also one of the reasons that we particularly love the Proven Winners butterfly bushes – they bloom all summer without deadheading. Older types of butterfly bushes do bloom better if their old blooms are removed, however. You can lightly trim the plant all over to remove them, or remove them individually.
Though they will perform well without supplemental fertilizer, fast-growing, vigorous butterfly bushes do tend to grow and bloom more when fertilized. We recommend applying a granular rose or garden fertilizer in early spring, then again in late spring and early summer. Never fertilize a butterfly bush past late July, as doing so can interfere with dormancy.
The best time to prune butterfly bushes is in spring, once the new growth begins to emerge on the stems. This makes pruning really easy, because the plant helps you determine where to cut: simply prune above where healthy new growth is emerging. The bigger the bud you cut back to, the thicker and more vigorous the growth will be. We strongly recommend waiting until spring to prune in cold climates, but if you must, you can give the plant a light trim in fall to neaten it up. Gardeners in warm climates (zone 8 and 9) can prune in fall if they wish.
Pests and diseases
Overall, butterfly bushes are pretty trouble-free plants. Deer and rabbits leave them alone, and they don’t get common diseases like powdery mildew and leaf spot. If plants are very stressed, they can break out in spider mites, which gives the foliage a hazy brown appearance. Spider mites can be managed with a horticultural soap or oil; if a plant had spider mites, it's a good idea to try and remove and discard all of its fallen foliage in autumn.
Still have questions about growing butterfly bush? Contact us, or take a look at these articles:
It’s spring, and nothing is happening. Is my butterfly bush dead?
How to grow butterfly bush in a container