In general transplanting in summer is not encouraged but this summer has been rather mild and cloudy. I did several transplanting as a result with very little damages. However it's not the heat alone that you should watch out for but also the sun and drying winds. I transplanted on cloudy days, rainy days and at dusk when it's dark. (neighbors probably think I'm nuts). In cases of plants like the NIKKO hydrangeas, I put a screen to filter sunlight and left it in place until the succeeding year when it was fully recovered.

Water well and several hours before you do any transplant. Try not to transplant any budding perennials, if so, remove the buds so the perennial can concentrate on root recovery. I would still avoid adding any fertlizers. Soft leafy perennials are especially vulnerable to water loss and so these do require a lot of mulching and watering. If it is a large plant with plenty of foliage, like my artemisia powis castle - I'd remove some branches to help the plant recover quickly (it worked). For shrub try as much not to disturb the roots. If it's an established shrub/tree, you will definitely require a large root ball.

Some folks have used MYKE to helpt the roots absorb nutrients.

Once you've transplanted them, mulch them well to help with water retention. I reused an old coconut coir as a mulch. You will need to be vigilant especially during the really hot sunny days.

Ianna

If you are getting 'cool and rainy weather this week', do it now! We are hitting the high 20s today and I'm building a new bed. This evening, all the transplants are going in - shrubs and perennials. The forecast is calling for 4 days of showers and rain after today. Good timing!!

Do you have to do it now or do you just want to do it now? If you just want to, then I'd not transplant anything that's going to be in the sun, since you're getting up to the high 20's low 30's next week. Tiffy's weather is what you really want when you're doing any transplanting.

If you have to transplant them now, then ianna's advice is spot on. It can be done without any losses, but you really have to watch them. I actually just divided a badly overgrown clump of Siberian Irises yesterday, but they are in pots I placed in the shade and they're getting lots of water.

BP