Wednesday, December 30, 2009

Lantana and butterfly bush (Buddleia) - invasive species everywhere?

As do I'm sure many gardeners, I've been spending some time in these winter months perusing catalogs and rethinking my garden design. As part of the potager I'm planning in our allotment, I've reserved one of the four quadrants as a butterfly and bee garden, but am now having second thoughts about two of the shrubs I wanted to have in it.

For years we've had lantanas in mini tree form on the roof patio of our city apartment, see below,

and I was appalled to read one day that they have been outlawed in some countries as invasive plants. Here's a link to an article about the havoc they are wreaking in various places. I had really wanted a lantana because they bloom tirelessly throughout the summer and are a wonderful magnet for bumble bees, bees and butterflies, including the intriguing hawk moth (picture taken from Wikipedia, see here).

 Link to Creative Commons licensing agreement which applies to this photo.

A hawk moth - rather unusual in our zone and with an uncanny resemblance to a humming bird - regularly visited the lantana (and the petunias) at about 4 p.m. all summer, delighting us everyday. The patio literally buzzes with activity due to this plant.

We are in hardiness zone 7, and the lantanas do not survive the winter outside, so I figure they don't pose that much of a danger here. I either take them inside starting in late November or purchase a new one in the spring.

The other shrub I wanted was of course the butterfly bush, Buddleia davidii, and in fact I've already purchased and planted a dwarf species, "Buddleia Flower Power".

Imagine my dismay on discovering that this shrub, too, is considered an invasive species in some places and is prohibited, for example, in Oregon. And it's on the black list of invasive species in Switzerland, right next door. In Germany there seems to be a border between areas where it survives easily (and I'm in that area) and areas to the East with a more continental climate, where it doesn't. But no official measures are being taken, and in fact, summer lilacs (as they are often called here), are very popular and widespread. I read that one of the reasons it became popular is that it could survive even on the postwar rubble of many Germany cities. But it is causing the German Railroad trouble, since it proliferates along embankments.

While researching I discovered that several other garden favorites here in central Europe are also considered invasive, including mahonia, Himalayan balsam (a kind of impatience), Japanese honeysuckle, and many others.

So I'd be interested to hear what all you gardening experts out there, especially at Blotanical, think about this. Am I violating a basic principal of good organic gardening by planting these shrubs in my garden? It's somehow hard to imagine that shrubs that are so obviously appealing to native fauna could be harmful.


  1. Careful deadheading will keep your buddleia from setting seeds. Deadheading lantana is more labor intensive, you might want to look into the cultivars that do not set seed.

  2. Thanks for the tip, NellJean, although with the proliferous blossoming of the lantana I can hardly imagine keeping up with them. I'll look into the non-seeding cultivars.

  3. I grow a few lantanas in my garden and it has attracted some beautiful butterflies. I think this is good because flowers get pollinated. I have read that it is invasive in certain parts of the world too. In Malaysia, some lantanas grow wild, especially in the jungles and countryside. Now I want to Wish you a Very Happy New Year 2010!

  4. Hi Barbara, I was so excited to see the name of your blog and that you are an American I thought I'd drop in. I lived in Heidelberg for many many years and loved Mannheim, especially Luisen Gardens and the Plantetarium. At any rate, I do not think you would violate any principles if you plant a buddleia or mahonia. Your part of Germany seems most similar to my part of Tennessee and knowing how the Germans manage everything so well in their natural areas there should be no issues. I say go for it. Have a great new year too! Don't forget to watch Dinner for One. I am looking for my multi system VCR so we can watch it here:)

  5. Lantana is invasive in South Africa, so, no, I wouldn't plant invasives. Of course if it is truly invasive, it shouldn't be for sale. Our hawkmoths used to come at 4pm to the basil in our last garden. That is not invasive and you can eat it. Find an indigenous/native German shrub that the butterflies like.

  6. Hi,

    I think the Lantana should be fine...since it really cannot take any frost and is fairly slow to grow from seed I doubt it could ever escape and become invasive in Germany. The Buddleias, on the other hand, are already all over the place in most milder areas. I remember that they used to self-seed all over our garden in the Black Forest and rapidly grow into big shrubs. In much of region they will fill uo any disturbed place within a few seasons. On the upside, they also sometimes colonize otherwise barren concreted sites and fill them with fragrance and insect life...

  7. Congrats on being such a responsible gardener with a desire to adhere to basic principles of good organic gardening. If a plant is termed invasive I always proceed with caution. That being said, what is invasive in one place might barely be able to survive or set seed in another. Here in Alaska, for example, many kinds of ornamental grasses that are termed invasive in more southern locales can be planted because our summer is too short (and cold probably)for them to set seed. Your local botanical garden, gardening clubs, or government websites might have more information about the invasiveness of a specific plant for your town/area. Your patio grouping looked very charming, I wouldn't want to part with the lantana tree either! Best of luck.

    Christine at Last Frontier Garden

  8. Thanks to all of you for these useful and knowledgeable comments. I think my strategy will be to conscientiously deadhead the buddleia and keep an eye on whether it's spreading, and to reserve the lantana for the patio on the fifth floor. I've already planned some other bee and butterfly attracting plants, such as wild thyme, oregano, lavender, wild carrots and muscari. The gardening association we belong to in connection with the allotment has no restrictions on buddleia, although they do have some on a few other plants, mostly trees.

  9. Barbara, I do think that good garden ethics require paying attention to concerns about invasive species. Often, the problem is that an invasive exotic takes over the habitat of a native plant, posing a threat to the native. In the northeast US, for example, the native cattails (Typha latifolia), and the fauna that depend on cattails, are threatened by the aggressive spread of the invasive exotic, purple loosestrife (Lyrheum salicaria). Purple loosestrife is a spectacularly beautiful plant, but I don't think it is ethical to grow it in this part of the world, and I try not to do business with nurseries that continue to sell it. -Jean

  10. I was getting curious about the law about invasive garden plants in our country (netherlands) but think there isnt one over here.
    Maybe because there is practicly no untouched nature. There are some nature parks though but most of them have an origine of farmland or production forests.

    I only found one plant which is forbidden, which is a water plant, and thats because it clogs up the canals so we cant manage the water anymore.

    In fact right at the bycicle lawn there is a hedge of the dangerous Giant Hogweed/Riesenbärenklau, everyone could reach it, even children could play in it if they want to, and if youll fall of your bike in summer you'l land in a nice bed of Giant hogweed. Probably someone in the USA would sue the owners after only looking at it, but in the Netherlands its no problem (WEIRD!)

    Well ok, i am drifting off, i have a budlea in my front garden, and had it for 5 years. It hasnt produced 1 seedling.
    I always cut the flowers after blossoming, because i think the bush keeps flowering longer.
    Mabe that did save me, although i havent seen them produce seedlings in any other garden with a budlea davidii. (= i think 25% of the gardens here, cause its a very populair plant)

    People here multiply budlea's with cuttings.

    I would try it just cut away the old flowers and throw them in the bin. Just watch the ground for seedlings to be sure (flowering bushes arent grown in 1 night so youll get plenty of time to weed seedlings if they seed) :)