What's the best time to move hostas and other perennials?

I'm pretty new to growing flowers. I'm trying to re-work a couple flower beds where last year I planted some things in too much sun, some too shady. Think I'm getting a better feel for how much sun there really is with our 100+ degree weather! I'd like to try moving the following plants: iris, allium, lilies, fern, hostas, heuchera. Also divide and transplant bugleweed, vinca, and strawberries. Can somebody tell me the best time of year to do this?

The area I'm moving most of those plants to is more shady. The soil is very clay, so in Feb. (in zone 6) I added an inch or 2 of rotten wood mulch and a couple more inches of grass clippings in March. That's mostly decomposed now and the soil is nicer but will need more help. Any suggestions for more amendments?

Your soil amendments sound like good things to add. The grass will add much nitrogen to the soil and the decomposed mulch will add other beneficial nutrients. If you're getting temps close to 100, you might want to wait until next spring to do the transplanting.

The best time to transplant ALL plants is end of summer, tree's, shrubs, bulbs etc all need the cooler soil conditions to be given any chance of recovering after transplant,

IF you miss that time, then next best time is EARLY spring, before the heated temps gather pace, the idea for those periods is, end of summer the soil is starting to cool down but still warm enough for the roots to settle, in spring, after winter rest, the soil is JUST starting to warm and it allows the roots to settle before the real hot weather arrives.

The plants you mention moving are a mixture of sun and shade loving types. Iris, Lily's, Alliums and Strawberries all like full sun, the others, Ferns, Hosta's and Heuchera all need cooler shaded areas.
The last 2 types of plants can take dappled shade to do well BUT NOT blazing sun.

Lori, I dont know the size of your borders / beds etc, so it's difficult to tall you how much additions you need to add to your soil to improve the quality and give your plants a good start..

As you are finding out, clay soil is hard to work with, both for the gardener AND the plants, in winter it can become wet ans sticky and clay soil cant hold onto to any nutrients you add, they run right through the clay way too fast before the roots have a chance to take up this goodness. the other side of clay is in summer, the soil bakes to a hard crust, the soil cracks and the roots dont get enough water, nutrients or even air that all plants need from the soil.

I'm so pleased you are starting to amend the soil texture, IF you can, pot up all your plants as you empty the beds, place in a cool area then set about working your soil.
My favourite soil improver is Manure, well rotted horse poo, lots of placed who have stables or horses for pleasure, like to get rid of the horse droppings for free. only take odour free manure, when you hold it between finger and thumb, it should crumble and smell like compost, dark brown in colour. It is natural, full of nutrients, when dug into the soil, the soil becomes instantly more crumbley and manageable, air gets into it and when you dig it, it is a joy to work with, not heavy big lumps and no goodness in it. it also helps to hold onto any moisture, all the things you plants need, the shade loving plants like a moist soil, NOT wet ansd soaking BUT just nice rich but damp soil. the Strawberries, like all fruiting plants need rich nutricious soil that wont dry out within 5 min's.

I would lay about 4 inches deep manure on top of the soil and as yuo dig, use your garden fork to mix the manure through the soil, it will end up looking like you have doubled the amount of garden soil in the beds but it will sink down again, BUT it will show you how much BULKY goodness you have added. The manure being added, you can plant up right away IF the manure was well rotted,

Try NOT to walk on the newly dug soil, use boards etc to lay across the soil and that spreads out the weight when you have to step onto the soil when planting, IF you trample the soil it becomes compacted again loosing the nice texture and all the air out of it.

Im so proud of you for doing all the right thing for your plants AND for your garden / outlook and pleasure after the works done, the more tasks you do the more you learn about gardening, but learning about your soil is the best basic start into gardening as no matter what type of plants you grow, you need to learn what their needs are.
Stay in touch and let us know how your doing and if you want further advice / help.
Good luck.
Kindest Regards.
WeeNel.

One thing about moving plants at the end of summer is you need to make sure they have enough time to root in to their new location before the cold weather begins. If they don't have enough time, sometimes they don't make it. I prefer to move things in the spring as the sun angles are getting higher and higher, things are coming out of dormancy, not going into dormancy. You're not wrong whichever you choose, just make sure you give them enough water.

Thank you for the advice! I have access to lots of old manure, so will add that in as well, plus some more grass clippings. If the weather cooperates I'll try to move plants in late summer. Mulch with leaves after the first freeze.

Keep on adding as much organic matter as you can, and mixed sources are just fine. Some materials will decompose pretty fast (usually soft, green materials like grass and manures) some will last longer (usually woody materials like sawdust, bark and chips).
Each material offers slightly different nutrients to the soil and to the microorganisms that thrive in the soil.

If you can mix it in deep enough, I would try to end up with about 50% organic matter + 50% original soil for shade plants. This would be achieved with 6" deep of compost tilled with 6" of original soil.
When the bed is empty of plants, add as much as you can, and mix it deep.
After it is planted keep adding thin layers of mulch and the mulch will decompose and work its way deeper into the soil.

Hi Lori, I've just read you plan to add leaf mulch AFTER the first freeze, best to add this end of summer / start of autumn soon as you can get the leaf litter, reason being, IF you add the mulch once the freeze has started, you will trap the freeze/ frosted soil under the mulch and this wont help keep the sleeping plants healthy over winter.

By re-setting out your plants end of summer, the plants have enough time to settle down into their new environment (Because the soil is still warm) come late October onwards, the plants (especially the ones you have) will go into their winter sleep and ALL parts of the plants go to sleep for winter and wont become active again until early spring, at that time as you tidy up the dead or sad looking top growth, you will offer a handful of a slow release fertilised that is organic, so I would use the ready mixed Blood / Fish / Bonemeal, this gets hand forked into the soil around the root area and should act like a slow tonic for the disturbed plants.
It is aslo best time to move plants LATE summers is because the cooler temps are more likely able to prevent the plants going into transplant shock, they wont have the reering hot weather to fight as well as trying to make new roots.

When you lift your plants, always try to remove some of the soil around the roots as this also help prevent stress because there is less root breakage etc.

As Diana also mentioned, keep adding as much humus (especially the manure types) as a top dressing / mulch and this can stay on top of the soil all winter, then come spring, it gets dun into the soil adding all the goodness the soil and plants require for healthy life.

Well done too for taking the time to ask how to and when to do the prep and care of the plants,
Your hard work will be evident when the new growth starts to show beginning of spring. Make sure you put canes and labels beside the plants when you have moved them as the top growth of a lot of the plants will hidden, its so easy to stand on underground parts of the plants and the tender growing tips get broken, Regarding your strawberries, When you add the mulch around each plant, try never to cover the heart and the greenery, make a little ring of mulch around these alloweing air into the top growth, this will prevent rotting,

I feel sure between us all, you will have a great new start for next years gardening so good luck and lets know how you get on.
Kindest Regards.
WeeNel.