Garden writer Nicki Goff wrote the following great advice about Spring care of Perennial Gardens. The article appeared HERE in March and I have posted at the Garden Log now because of its timely value!
I would be careful with her advice about iris; I don't think iris should generally be dug and divided until fall. Otherwise this is a superb article and I agree wholeheartedly with what she writes. If you have any questions, please contact us at firstname.lastname@example.org. Here it is!
Spring is a good time to rejuvenate your perennial borders and gardens. If you're at all like me, you enjoy the thought of getting out in the cool but pleasant sunshine after a winter away from your gardening. Spring is easily one of the busiest times of the year if you have a garden full of perennial plants.
"Not all perennials will have been cut back in the fall. Some you have left so the interesting seed heads offer winter interest. Others fare better with some of the foliage left in place to protect the crown of the plant. Spring cleaning of the perennial beds includes removing any of the old dead foliage and seed heads.
Be careful as you do this. If the ground is still wet, walking on it will compact it and close up the air flow to the roots. It's better to wait until some growth is visible so you don't damage the emerging stems. The old growth you remove can be added to the compost pile as long as it is not diseased.
If you have mulched some of your perennials in the fall for winter protection, you can remove the protective mulch and compost it. For more tender perennials, leave the mulch in place until all nights are frost free.
Rockery perennials like aubretia, sea thrift and thyme should be given a haircut, removing any old blooms or seed heads. This shearing back will encourage new bushy growth and later flowering. With others like heuchera, remove any dead or damaged leaves.
Ornamental grasses are becoming a common element in landscaping. You've probably left the seed heads of the fall blooming ones like Miscanthus in place for winter garden interest. If you have these, chop them back before they start their spring growth.
Spring is a good time to divide perennials. Dividing perennials allows the crowded root systems more space to grow as well as giving you new plants to expand your planting or to give away. Each perennial is divided differently, so know how to divide the ones you have that are in need of dividing.
Clumping perennials like hostas, yarrow, phlox and perennial lobelia are easy to separate into individual plants once the clump is dug up. Replant each section in good humus rich soil and water well as you set it in place. Spring is also a good time to relocate any perennials that need a new spot.
In the case of summer-flowering iris, new fan shaped arrangements of leaves will appear along the rhizome. Dig up the entire rhizome and cut it into healthy sections that contain both leaves and roots. If any roots show signs of iris borer, dispose of them in the garbage, along with any dead foliage, and replant the healthy rhizomes in a new location. Note: this can be done EARLY in spring but by mid April it is getting late for this. Best done in the late summer or fall!
This is a good time also to get rid of the weeds, while they are still small and not deeply rooted. They are much easier to pull when the soil still holds winter moisture. Once weeds are removed, you may want to add a new layer of mulch to retain moisture and discourage any new weed growth."
April 15, 2010