I began winter sowing in 2009 and that first year grew butterfly bush 'Black Knight' from traded seeds. It continues to amaze me that Buddleia is considered invasive in Pennsylvania but not here in CT.

The plants I grew via WS have not replicated themselves and I planted them in multiple garden beds--two on the north side of my little green acre, two on the south side & two on the west. (NB: the seeds germinated at what appeared to be 100%--the sprouts in the milk jug looked like Chia pets.) They come up every year and this was their most robust season based on how tall they grew rather than how prolific they bloomed.

I heavily mulch my garden beds and spread bark mulch over thick, corrugated cardboard to suppress weeds. That said, other prolific reseeders (ladybells) + invasive weeds (violets, creeping Charlie) have ignored my efforts.

I think the jury's still out whether they're invasive in your Z5 garden Kevin since that's the low end of their hardiness range. I will qualify my comments since I've only ever grown what I believe are 'Black Knight' cultivars.

That said, after 4 years of enjoying them in my garden beds, I wouldn't be without them. The butterflies absolutely love them and that's one reason I garden.

I dunno what it is..but I planted 3 buddleias over years in one location (only place I wanted one) in Oklahoma (z7) and never a one thrived (or even survived). At least I didn't have to worry about reseeding (lol).
It's sad when you can grow almost anything and something that seems like a common plant refuses to grow for you.

It depends on your climate - where winters are not too harsh and there is sufficient rain they are an alien pest. They prefer very well drained situations such as along railway tracks and in old masonry. This one's just down the road from me.

dbarron - I'm sad to read Buddleia didn't grow for you. My soil is reasonably healthy sandy loam--plump worms show up every time I sink a spade into the soil thanks to my parents practicing organic gardening for 50 years before I moved back to the homestead. You might want to have your soil tested to decide if that's what doomed your Buddleias.

A few of my winter sown* Buddleia plants are growing in beds where voles & grubs are active--I've lost a couple of nursery-grown Baptisia/false indigo plants to those varmints. The Buddleias growing in those same beds haven't been bothered by any predators so far.

I'm guessing their water needs are average but can't guess what the water conditions might be where you are. I don't give any of my WS Buddleias supplemental water--they get only what Ma Nature doles out. According to Google, they're drought-tolerant which makes me think yours might be a soil issue.

*FYI - Winter sown perennials are healthier than nursery-grown plants so I'm guessing the reason my Buddleias are more robust than hothouse plants is I grew them from seed outdoors in winter and didn't interfere with Mother Nature's plans as regards moisture/temperature/hours of daylight.

Well, it doesn't sound like self-sowing is much of a problem for most people. Maybe like floral says, it's much more of a problem in the much warmer, moist climates (that's a pretty impressive survivor growing out of that wall).

I think my mind probably immediately went to something like the American Elm which is admittedly so sacred to most folks, but not to me. Yes, it is/was a beautiful, grand shade tree, but the most hellish seed producer I have ever encountered.

Before mine came down, I was cursed with snowstorms of seeds every summer - by the 10's of thousands if not 100's of thousands and I swear to god, every seed that touched soil germinated. I would take me the entire summer to rid myself of them only to repeat the process the next year and on and on.
I didn't want to get myself into another situation like that with a fertile Buddleia.

Kevin

Self-sowing the the garden is seldom a problem.

The reason they're invasive in some states is that the environment enables their germination at a distance. Here in Oregon, they seed into mountain top clear cuts and along waterways.

The conditions jean001 describes are exactly the kinds of places Buddleja self sows here. Although we don't have mountain tops, it is the presence of fast draining, loose, often stony ground which is optimum for this plant. Maybe some of the lack of success in gardens is from giving them far too rich a habitat.

I found a bizarre twist to the Buddleja story when I was looking at Google images recently. It is such a common feature of our railways and other industrial waste ground that modellers are busy making tiny fake Buddlejas for their train sets to increase authenticity. Maybe if you can't grow one in the garden you could make yourself a tiny replica? ;-)

Here is a link that might be useful: Make yourself a mini invasive alien

Kevin, I have several buddleias including two that are 10+ and 7+ years old. Most were winter sown over five years. None of them has shown any evidence of self sowing.

mnwsgal - So it looks like these can be hardy around here. Which ones do you grow and do you do anything special for winter?

Kevin

Kevin - my winter sown Buddleias get the same treatment other hardy perennials get which is that I do nothing special for them until spring. Towards the end of March I simply prune the stems back to about 10". That's all the maintenance they appear to require. They bloom on new wood so the annual pruning encourages increased flowering.

There are many new cultivars that appeal to folks looking for specific flower colors or plant height--I simply grew 'Black Knight' because I got the seeds in a trade and read that it was reliably hardy in my zone. A few years ago I did buy a couple of nursery-grown named cultivars with yellow or white flowers but they never came back the season after being planted.

I have 'Pink Delight', 'Empire Blue' and 'Miss Ruby' as well as another NOID. They are all in full sun amongst perennials. I cut them back to near the ground and mulch with shredded leaves to overwinter. I tried twice with 'Black Knight' but it did not survive the winter. 'Miss Ruby' was ws from commercial seed and is in a holding bed and I do not remember if it bloomed this summer.

Several other plants were grown from winter sown NOID mixed seed and have been given away.

I never thought to color the sugar sprinkles myself.... duh!

Kevin you would probably have the best luck with a small plant planted in the early spring, not a gallon container plant. If you do try a larger plant, I would almost bare root it when planting to really get it established in your soil rather than leaving many of the roots clumped up in the original potting soil. The soiless mix from the container will likely hold water differently and freeze and thaw differently and stress the plant over winter.

kato

When I planted my Buddleia 'Blue Heaven' this past spring, it was a small plant in a 3 1/2 inch pot and I was absolutely blown away by how fast it grew. I'm so used to shrubs not doing much the first season or two, so to have a very respectable blooming sized Buddleia the first season from such a small pot size sold me on the idea of ordering more small plants this spring.

Sugar sprinkles: Be warned! It's kind of an addictive process. Once you discover how easy it is to do, it's hard to stop with a few basic colors.

Kevin

One year, maybe two or three years ago, I noticed about 20 self-sowed Buddleia growing in my beds. I have never noticed any before and none since. I think there may have been heavy late-summer rain that year.

I notice some growing wild, not so many to seem problematic.

My garden contains 4 mature Buddleia. My soil is rich loam and mildly acid.

Some combination of conditions allows for self sowing. I just can't figure out which ones!