Butterfly bush, fluttering and buzzing all around fabulous flowers

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Long, nectar-rich flower spikes on a fast-growing, round shrub draw a constant traffic of butterflies, bees and hoverflies through the summer. The butterfly bush (Buddleja davidii is the most widely grown species) copes with almost any soil, but full sun is the one thing to get right — in part sun the plant is markedly less lush.

The butterfly bush definitely deserves its name. A particularly melliferous and flower-bearing shrub, it is indeed a paradise for pollinating insects of all runs: butterflies of course, but also bees, hoverflies, bumblebees, etc. Easy to plant, it will quickly decorate your garden thanks to its fast growth and magnificent summer flowers.

Planting a butterfly bush

Buddleja can adapt to all types of soil. Its only real requirement is exposure: full sun is, by far, preferable. Nonetheless, it will still survive in part sun, but it won’t grow as lush.

When to plant Buddleja ?

The butterfly bush, in a perfect world, would always be planted in fall. Planting that takes place in that season indeed lead to better settling in and faster growth for plants. It gives them a few months to grow new roots before spring and summer come around (when water often is wanting for days on end).

How to plant a butterfly bush

The size and shape of Buddleia make it compatible with planting in small gardens, and even in a container if you so wish.

Directly in the ground:

After determining the right spot for your butterfly tree, just follow these steps to plant it:

• Dig a hole about 12 inches (30 cm) deep.
• Layer some soil mix along the bottom and mix it in with garden soil.
• Remove the pot from the shrub’s root clump, and break the clump apart, extracting roots in a spiderweb-like pattern. This step will spur root growth towards the outside of the initial root ball.
• Settle the butterfly bush in its hole, and backfill it without burying the portion of the stem that connects to the roots: the root crown. For guidance, lay a rake handle or straight stick across the hole: it will mark normal “ground level”.

Butterfly bush in a pot:

Thanks to its tight, bushy bearing, Buddleia does well when planted in a pot to decorate a deck or terrace. Planting is quite similar to when you’re planting in the ground.

• Select a large container, and, if possible, with a water retention system (to reduce the need for watering).
• Make sure the pot has drainage holes underneath it. If there aren’t any, make 3 or 4 with a hand drill and a large drill bit (for cutting ceramics).
• Spread a drainage layer, taking care not to clog the water drains. You can use gravel, clay balls, etc.
• Fill the pot with soil mix, and top it off with plant-based soil. If you want, you can amend the substrate with vermiculite (or perlite) which enhances drainage while retaining some of the moisture.
• Plant your butterfly bush following the same steps as for planting directly in the ground.

Butterfly bush care

Depending on how it was planted, you won’t care for it in the same manner. There is, though, one point that is the same for both: pruning. To keep the shrub dense and compact, you must cut it back the moment all leaves have dropped back.

For the tree planted in the ground, this is the only work you’ll ever have to do.

For a potted butterfly bush, there are a few extra steps:

• Keep an eye on water needs so that the soil doesn’t get too dry.
• Add nitrogen-rich fertilizer in spring, and potassium fertilizer in fall. Best go for slow-release, granulated fertilizers so that the shrub has time to absorb the nutrients inside.
• Repot every 4 to 5 years.

Propagation

To create new butterfly bush specimens, simply prepare softwood cuttings.

Note, however, that the butterfly tree very easily propagates naturally through seed.

Since it’s sometimes classified as an invasive species, it helps to be forewarned.

Some studies have shown that certain cultivars like ‘Nanho Purple’ and ‘Dartmoor’ have a high germination rate, whereas others like ‘Black Knight’ and ‘White Profusion’ are slower to spread.

• Take butterfly bush cuttings from non-flowering shoots, trim each to a few pairs of leaves above a node, remove the lower leaves and keep the pot humid and shaded until roots form.
• Cutting off the faded flower spikes before they turn brown and dry stops most seed forming, which is the simplest way to curb a butterfly bush that self-sows into the surrounding garden.
• Pull up unwanted butterfly bush seedlings while they are small and their roots still come away easily, because established ones root deeply into gravel, walls and paving and are far harder to remove.
• Seedlings of a named butterfly bush cultivar rarely match the parent in flower colour, so propagate by cuttings whenever you want an exact copy of a plant you already like.

Which butterfly bush cultivars spread the most?

Because the butterfly bush sets seed so freely, the cultivar you choose decides how much seedling clearing you will be doing later. The four named below behave very differently.

Since the shrub is sometimes classified as an invasive species, the slower-spreading cultivars are the safer pick.

Diseases and pests

The butterfly bush is very resistant. It thus isn’t vulnerable to diseases, and pests don’t seem to find it interesting (apart from aphids, but they’re only really a problem when in very large numbers).

• Avoid spraying a butterfly bush with broad-spectrum insecticide: the shrub attracts feeding bees, hoverflies and butterflies, and such sprays kill these visiting pollinators along with any aphids you are targeting.
• Heavy aphid feeding leaves sticky honeydew on the leaves, which turns black with sooty mould and attracts ants that protect the colony, so treat before the numbers build.
• Waterlogging harms most garden plants: in heavy clay, or in a pot whose drainage holes are blocked, roots can rot, so improve drainage or plant on a slight mound.

Landscaping uses and companion plants

Regarding possible uses, the butterfly bush has a lot to share: standalone, in a group as part of a shrub bed, in the ground or in a pot; the choice is yours to make!

Buddleja isn’t very demanding, so you can pair it with many other types of shrubs like lilac, photinia, forsythia, hamamelis that will provide colors and blooms when the butterfly tree doesn’t. Another option is to find different colored butterfly bushes and plant them together to create a patchwork of colors during the blooming season.