I've had good luck just splitting them with a trowel and replanting them. I've done this in the summer.

I'd wait until spring now, sometime in April when the new growth appears.

You can do it now. Fall is optimal time for planting/transplanting/dividing - cool days, warm soil = perfect conditions for root growth.

If you do decide to do it in spring, I would wait until after it blooms; if you divide before it blooms, you may end up sacrificing the display for the season.

You should be fine to divide now. I divided one last year in late September to see what the results would be this year. The division was about 3/4 to 1/4. The 1/4 piece was the one moved, but the 3/4 piece stayed in it's original place. Here it is in July of this year - the biggest one in the back. Please pardon it's seedlings which I planted in front out of curiosity. :O) As you can see some of the seedlings do not come true but could add value to other sections of the gardens next year.

{{gwi:199220}}

I am north of you in Nova Scotia, Canada, so you should be fine doing it now.

I divided Jack last fall and they were fine this year. I also left one undivided and it bloomed a bit more than the others this year. but other than that they were all great.

go for it! As with all divisions, be sure to prepare the soil well and water well.

When Jack Frost reseeds it does not come back like the mother plant.It comes back as just a green leaf not variegated .Is that normal?Peter zone 4

Not an expert, but I don't think mine reseeds. And I've found brunnera one of those things that is ridiculously easy to divide - the smallest division will turn into a big plant by the end of the season.

Me too Peter Duffy. (The reseeding is not major and so not a problem).

The seedlings from a named variety can run the entire range of the genetic make-up of the parent plant. So it might be non-variegated or it might have similar variegation or it might have more variegation. So what you are seeing are entirely within the range of what is possible. Named commercial varieties are reproduced by division for a plant like Brunnera.

Out of the 1/2 dozen seedlings I have had one has been green and the rest quite close to the original.

The only brunnera cultivars we have (9) with seedlings evident in fall, are 'Langtrees' and 'Alexander's Great'. They're both located in rather open spots. Suspecting the seedlings of other cultivars are shaded out, along with the weeds, by taller perennials through the summer and early fall.

Formerly noted run-away seeding in the species (Brunnera macrophylla) and have avoided planting it in mixed perennial gardens ever since.

sunnyborders? I dont think I/we have seen you much this winter. Good to see you back and about.

Thanks, Rouge.

Leaving Fort-de-France, Martinique (unfortunately). Currently the frozen garden's back under snow. Suspect it's no better for you.