I do it in our long fall, with a spade. Easy!

I find problems with doing it in the spring include: (1) interferes with the spring bulbs and perennials, (2) don't want to compact the soil of the wet perennial beds and (3) sometimes not sure what's plants what.

I have done it in Chicago, at both times of the year.

In the fall: Just get them in the ground in plenty of time before the ground freezes, the earlier the better. Shoot for Labor Day to mid-September. Mulch well after the ground does freeze. This will moderate the soil teps and keep the plants from heaving out of the ground during freeze-thaw cycles.

In spring: This is weather dependent. You could have frozen ground longer than you think. You could have snow in April. Then the plants must get established, but if you get a sudden heatwave, that could be a problem.

I've just talked myself into thinking this is best done in the fall. The plants get established easier because the soil is still warm. Springtime soils are too cold to promote root growth.

Thank you both for your answer and helpful advice! I was thrilled to read fall would work. I love working and doing as much as I can in the fall for reasons you both mentioned. Thanks again for helping me out!

Actually Mary, I would definitely not divide them in autumn/fall (or any other plant which flowers later in the year than the end of June). They have a tendency to rot in the ground whereas dividing in spring as they are starting into growth is the best time to do it. Asters are also particularly picky in this respect (I have lost whole clumps, trying to do an autumn division) - paeonies, on the other hand, thrive with a fall division.......

I do the majority of plant division in the fall, always did. Even with plants like ornamental grass that is not recommended. I have always had great success. The 1st week of Sept is when I start and with things like hosta and daylilies right up through Nov. There is time to do it in the fall, thats my deciding factor. The ground is warm in fall and on the Great Lakes spring could come late. As much turf seeding as possible is saved for the fall with much better results than spring. The wet cool August has me moving some things already.

Beautiful picture, Sunny. Those plants look fantastic.

I always divide Echinacea when they start growing in early Spring. Some Echinaceas won't survive the winter, even if you just PLANT them in the fall. To survive winter, they need as big of a crown as possible. If we are talking about the new hybrids, I would use caution in the fall especially. Some of the pink Echinaceas could do ok with dividing in fall, but all of them do well when they are divided while actively growing in early Spring.

Thanks a2zmom.

The only Echinacea I've divided (in fall) is 'Magnus'.

This post was edited by SunnyBorders on Mon, Aug 5, 13 at 10:24

That is a wonderful photo!

The fact is, the only things that can really kill these plants is diesase. I have dug them up and left them for weeks outside and they continue to thrive before I remember to plant them. This is SO not rocket science, folks. Echinacea and Rudbeckias can be dug up and moved just about any time and they do fine. It's just that fall seems to be a better time. I also agree that it's more enjoyable to divide and transplant in the fall.

The OP is in Zone 5, possibly Chicago? Nothing rots in the ground up there in winter. Heaving may be an issue, but mulch stops that.

These two plants can take an enormous amount of abuse and neglect and live to tell about it. Some gardening projects are complicated. Not this one.

Thanks, crunchpa.

Interesting, Mulchmama.

Going back to what campanula said, a lot of it must be local growing conditions.

Where we are, spring and summer tend to have limitied precipitation. The spring moisture is melt water from the snow. Fall and winter tend to have more precipitation (rain in fall and snow in winter). I have to thank David Tomlinson of Merlin's Hollow (in Aurora, On, where we live) for this generalization.

There's part of a rationale for fall planting (potentially a fair bit of ongoing rain), at least here, especially for plants which are local in origin (e.g. New England asters).

This post was edited by SunnyBorders on Mon, Aug 5, 13 at 17:22

I killed an Echinacea last fall with what I think was a too late transplant. I would try and do it while it's still green and growing (not too late)... I do tend to push the fall season with planting ad transplanting whenever the ground's not frozen solid.
I don't think you can kill the black eyed susan.... if you want even more just sprinkle the seed heads around and you'll soon have it everywhere!

I am in Chicago area. Fall (September to early Oct) is my favorite time to divide and transplant and plant for reasons other already stated. Black eyed susan and cone flowers are the more durable plants. You can not kill them (except rabbits this year have been eating some of them to the ground so I lost flowers but plants will come back next spring).

A few plants that have shallow root are better divided or planted in spring: mums, Shasta Daisy, Asters, etcs