Tip from the test garden

Refresh clumps of bearded iris and gain new plants by dividing their underground stems (called rhizomes) anytime after bloom; in desert areas, wait until soil cools in fall.

1. With a spading fork or a spade, gently lift rhizomes from the ground and shake off soil. With a knife, cut the parent rhizome into segments so each has its own leaf fan. With pruning shears, trim leaves to about 6 inches.

2. Let cuts heal for a few hours, then replant divisions 1 foot apart so leaf fans are parallel and facing full sun. Set rhizomes barely below the surface; in hot-summer areas, cover with ½ inch of soil.