The Iowa Gardener: Benefits of delaying spring garden cleanup

Thinking is changing on spring garden cleanup.

The goal used to be to get out there as soon as possible in March, once bulbs started emerging from the ground and perennials starting showing signs of growth, to pull away winter mulch, leaves, dead plant material and anything else.

But now, a better understanding of how pollinators and other beneficial insects work — and their diminishing numbers — means factoring in how pulling away dead garden material can impact these vulnerable creatures.

The Xerces Society, committed to preserving pollinators and other invertebrates, says that as long as there is a danger of frost (which is mid-May in the Cedar Rapids area) last year’s leaf litter is still providing protection for both plants and invertebrates against late-season frosts. Also, until that time, butterflies' chrysalides will still be clinging to dried stems and twigs, waiting for the right time to emerge as adults.

Even once you start seeing bumble bees and ground-nesting bees emerge as flowering trees and shrubs burst into bloom, they still need cover during chilly nights and heavy spring showers. Mining bees, mason bees, carpenter bees and bumble bees may be out and about by early April, but other species such as sweat bees are still hiding out, waiting for warmer days to arrive in a few weeks.

Pollinators also benefit from lawns being left alone a bit longer than we traditionally might. The Xerces Society recommends delaying mowing until soil temperatures hit 50 degrees, to make sure that most pollinators have had an opportunity to emerge from the soil unscathed by a mower blade. This happens about the same time as when the bright yellow forsythia bushes start to bloom.

To help pollinators the most, consider waiting a little longer to mow. Also consider being a part of No Mow May, the movement to allow grass and wildflowers in lawns to grow unmown until after May, creating habitat and forage for early season pollinators when floral blooms can be less common.

Overall, the general principle is that if you want to do what is best for bees and pollinators, leave your garden alone until early May.

However, if you want to do what is best only for your plants, that's another matter.

The down side of waiting until June to mow is that it's not ideal for the vigor of your lawn. Turf grasses do best when you mow them frequently, never removing one-third of the leaf blade at a time.

There are some plants that will do just fine with no action by the gardener until May, but there are others — especially low-growers like mums, hardy geraniums, ground covers, and others — that will turn leggy, yellow and weak from lack of sunlight, or become prone to mildew and even rot if they stay covered by leaves and other fallen perennials.

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In the vegetable garden, March is when many gardeners start tilling and planting.

Each gardener has to determine for themselves on how to approach this dilemma, but for me, I'm adjusting by doing less clean up in the spring than I used to. I'll cut down some of the most unsightly dead plants and push aside (rather than remove) dead leaves and cover off those low-growing plants that need to see some sunlight.

With the lawn, I'll probably wait until I can't stand it anymore and mow once the grass gets 3-4 inches high, which is usually some time in late April.

In my vegetable garden, I'll remove what I need to when I need to in order to make room for new plants, but not go crazy pulling out everything and tilling the whole think under at once. I'll be a little more careful, limited, and strategic.

And overall, I'll try to find other ways to help bees, butterflies, pollinators, birds and the environment. I've all but stopped using synthetic garden chemicals on my lawn, and am reseeding those pesky areas that always struggle with microclover. I no longer use any type of pesticide (insect killer) in my garden, and I use any herbicide (weed killer) very sparingly and specifically. Each year, I also incorporate more native plants, which are naturally more resilient and provide the ideal food and shelter for birds and pollinators.

There's another benefit with waiting to clean up and avoiding chemical inputs: It's easier and cheaper, and we can all benefit from that.

Veronica Lorson Fowler is co-publisher of the Iowa Gardener website at www.theiowagardener.com.