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Ask the Gardener: How to save irises and monarch butterflies

Ask the Expert
Monarch-Butterly-Caterpillar-Butterfly
Monarch caterpillar and butterfly. Frank O'Donnell/Globe file

What to do this week The rainy weather has almost made up for our spring water deficit. Continue plant shopping, but wait for the garden to dry before planting so you don’t compress the soil. Damp soil helps you pull out long roots like dandelions in one piece, however, so weed invasives now before they go to seed. Cut roses in the morning or evening just above an outward-growing leaflet to encourage an open direction for new stem growth. Re-cut the ends of flower stems under running water just before arranging them. Sprinkle fertilizer around spent spring bulb foliage and wait until it turns completely yellow before removing it. Transplant tomatoes, squash, peppers, melons, cucumber, and eggplant into the garden. Sow cilantro, beans, carrots, and corn. Pick lettuce, spinach, strawberries, and peas.

Q. My irises are doing well, but they are surrounded and crowded by violets and what looks like evening primrose. Will the irises be hurt by these wildflowers growing with them? I love violets and primroses, but I love the irises more.

J.C., Dover, N.H.

A. Violets and evening primrose (Oenothera) are aggressive plants that probably seeded themselves in your flower bed without your permission. Instead of wildflowers, I would call them weeds, which I define as any plant growing where I don’t want it. Even a pretty plant is not desirable if it overwhelms its neighbors. A gardener is a bit of a horticultural police officer whose job includes protecting the resident plants from invaders. I used to take a wait-and-see attitude toward sprouts of unknown origin, hoping they would develop into some kind of delightful free gift from nature. No such luck. They all grow up to be thugs.

Removing them is hard work. When weeds are relatively few and small, this is weeding. When they have taken over, it is time for a garden renovation, and you may have to hire someone to do it. The “good’’ news is that common iris flowers (which have fuzzy beards a little like caterpillars) like their roots to be dug up, divided, and replanted a foot apart about every five years to give them enough elbow room to bloom well, so combine this maintenance chore with evicting the weeds. After they have finished blooming, cut back the iris stems and foliage by two-thirds for neatness, and dig all the iris, primrose, and violet roots out of the garden. Hose off the soil, exposing fleshy iris roots that look a bit like fresh ginger from the produce grocer. Discard the skinnier violet and primrose roots and any seedpods in the garbage. An inexpensive soil sifting pan from the hardware store can help separate bits of weed roots from your soil. Divide the cleaned iris roots into smaller sections with three fans of foliage attached to each. Replant them horizontally under only 1 inch of soil. Give away your extra clean iris roots or move them to another bed. Pull out new weeds that sprout in the coming months.

Unfortunately, some professional yard crews are trained to “mow and blow’’ (with much noise and air pollution) but not to weed. This is why the suburbs have many lawns and few gardens. Like home cooking, gardening is a DIY affair. Young people looking for extra money could do well learning how to weed and then charging older neighbors whatever the market will bear.

 

Q. What can I do to help save monarch butterflies?

G.F., Millis

A. These beloved orange- and black-striped butterflies are in trouble, partly because climate change is making their annual winter migration to Mexico more challenging. You can help them by growing milkweed, the only plant their fussy caterpillars will eat. My favorite kinds are brilliant orange Asclepias tuberosa and wild pink Asclepias syriaca, which spreads underground into colonies in my sunny shrub border. June is National Pollinator Month. Celebrate by avoiding pesticides, which kill insects and are generally more dangerous to pets and humans than herbicides, which kill plants. Ask your tree and lawn companies about alternative treatments. Visit www.fws.gov./pollinators/ for more information.

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