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Chicago Gardener: Dividing irises
If a clump of iris bloomed less this year, it may be crowded. The cure is to divide the clump -- and August is the time. Wait until the leaves yellow. Then dig up the clump with a garden fork. Examine the fat underground rhizomes closely for evidence they have rotted or been eaten; either is evidence of iris borers, the larvae of a kind of moth that lays its eggs on the leaves. Cut away any damaged part of the rhizome and discard it in the landscape waste, not the compost. Cut the remainder into pieces, each of which should have a fan of leaves and a few roots. Trim the leaves no shorter than 6 inches and replant the fans, after seizing the chance to dig in some compost.
More squirrels? A gardener annoyed by squirrels digging in his planters wondered if the population was up this year. There might be more squirrels in some areas, says Steve Sullivan, curator of urban ecology at The Peggy Notebaert Nature Museum in Lincoln Park (naturemuseum.org) and top dog of Project Squirrel (projectsquirrel.org), which recruits citizens to help monitor squirrel populations. But squirrel populations vary enormously from one place to another, depending on food supply, he says.
In an urban neighborhood such as Lincoln Park, summer brings a bounty: the trash humans leave when they eat on their patios or in parks. But in far-out suburbs such as Vernon Hills, where squirrels depend on mature trees, midsummer can be tough. Nuts and fruits aren't ready, and garden plants have grown too big and tough to chew. So about now, hungry squirrels may start digging for half-eaten nuts they stashed earlier.
"Squirrels are constantly digging in your flower pots," Sullivan says. "Sometimes it's to bury things and sometimes it's to dig things up."
Can you stop them? Animal repellents, especially those containing hot pepper, may be briefly off-putting, Sullivan says -- but only until the animal figures out that the strange taste or scary smell doesn't really bring danger. The best defense is a physical barrier. For example, a layer of 1/2 -inch chicken wire, placed over the soil and covered with mulch, will prevent squirrels from burying food in planting beds or pots.