"God made rainy days so gardeners could get the housework done."
Good golly Miss Molly: more point/counterpoint on Oe and whether overwintering perennial milkweeds such as Asclepias curassavica encourages Oe spore transmission, yada-yada...
Since we've been touching upon winter pruning and cleaning as of late, for those who grow Butterfly Bush (Buddleia davidii), severe pruning (Yikes!) is recommended to encourage abundant blooms and keeping the plant within bounds, especially the standard varieties that can reach 8-12 feet tall if not maintained.
There isn't a consensus as to how drastic one should prune: to each their own. Some leave 3-4 foot stems. Others prune buddleia down to 6-12 inch stubs. I'm in the 6-12 inch camp regarding standard growers.
The Container Butterfly Garden is home to B. davidii 'Nanho Blue', a dwarf that if left to its own resources would reach only about 4-6 feet. It's not cut as drastically as standards are (doesn't need it), as 'Nanho Blue' and other dwarfs grow more compactly.
Here in SoCal, winter/late winter pruning is recommended, although, they can be pruned back into mid spring without too much negative impact. The earlier buddleias are pruned, the less chance of retarding spring bloom later in the season. Once those leaf buds start to swell and unfurl leaves, it's time to prune, if it hasn't been done already.
The video below demonstrates how to cut standard buddleias almost down to the ground. Chris in the video lives in Michigan and cuts his back in April, most likely due to later spring arrivals his region experiences. Here in SoCal, pruning is recommended at a much earlier date. By April , they are already growing vigorously, getting ready to set blooms in the coming months.
Here's a little diagram detailing how to Prune and Shape Buddleia.
BTW: buddleias are super easy to propagate via softwood and hardwood stem cuttings. If you have a favorite plant you wish to add more of to a garden or give a plant to a friend for the price of a bit of time and a little bit of potting soil in a container, cuttings are a perfect solution. With cuttings, the plants you create are mirrors of the mother stock, whereas germinating seed can produce genetic variability, especially when using seed from hybrids and cultivars:
- This guy is not a sheila. Love that thick, square, iron-jawed stance mate! HOW TO GROW PLANTS FROM CUTTINGS. Everything about this guy is bold, even his YouTube video title.
- How to Propagate a Butterfly Bush details making one's own cutting soil and how to take softwood cuttings.