From the ground up: Soggy, rainy conditions are stressing plants

Knowing how to counter the side effects of drought as well as excess water important

Water extremes are starting to become the norm in Iowa. It is important to know what to do to counter the side effects of drought as well as excess water. Linn County Master Gardener Lisa Slattery fills you in on what to expect with all this moisture.

Q: What are the effects of too much moisture in our gardens and landscapes?

A: Rain barrels across Eastern Iowa are full and not too many gardeners have had to get out a hose. The cooler temperatures have helped with utility bills, but all this excess rain and low temps are causing stress to our yards and gardens. Gardeners are noticing slow growth, spotting of plant leaves, rotting seeds, roots and stressed out trees. Fungus, bacteria and some annoying insects thrive in wet conditions. Plus, it’s a double-punch on our trees following last year’s excessive dryness and high temperatures.

Many trees are showing signs of suffering the loss of what are called the fine roots or new roots that take in moisture. These fine roots dried up and died last year with no rain and excessively high temperatures. Without fine roots, trees can’t take in adequate moisture, even though there is plenty. ISU Extension arborists expect to see adverse conditions that will affect tree canopies this year. There are already reports of leaf drop which is due to Anthracnose, a common fungal disease of trees in Iowa which affects ash, sycamore, maple, oak and walnut trees. Anthracnose thrives in cool, rainy weather. ISU also expects to see more fungal diseases of fruit trees and spruces, as well as more rust type diseases on crab trees.

Conifers throughout our area are really stressed after several years of too much moisture, last year’s drought and this year’s cool wet spring. When conifers get too much water, their roots don’t take in proper oxygen. This is referred to as “wet feet” which will invite fungal diseases in many conifer varieties including Black Hills spruce, White fir and Arbor Vitae.

Vegetable gardens are also target for fungal diseases. There are several fungus spores and bacteria that thrive in wet cool conditions, affecting almost every type of vegetable. Black Spot and Gray Spot disease infects “brassicas” or cabbage, cauliflower, broccoli and brussel sprouts. Early Blight and Septoria Leaf Spot are common fungal diseases of tomatoes. This year, tomato plants haven’t grown much yet, making them more susceptible to fungal damage.

Garden slugs also thrive in wet conditions. So do some bothersome insects such as mosquitoes and gnats. Even though slugs are not considered insects, they require moist soil in which to lay their eggs and cool, moist, sheltered sites to hide during the day. Mosquitoes lay eggs in standing water.

Mushrooms are also popping up in lawns and gardens. But they will stop growing when the weather dries up and they don’t cause permanent damage.

Most lawns should survive wet conditions; just avoid mowing wet lawns which leads to compacting your soil and spreading fungus. Lawns that have been flooded may not survive since standing water will drown grass roots, which require air to survive. Lawns may be more susceptible to rust this year, but that should not permanently hurt the lawn.


Summer Solstice Party, 5 to 7 p.m. Friday at Earth Source Gardens, located along Harvest Road at the northeast corner of Rochester Avenue and Scott Boulevard, Iowa City. Music, chickens, garden tours, children activities and demonstrations.

True Lilly Garden Walk, 10 a.m. to 6 p.m. today, Friday and Saturday at My Savanna Gardens, 6161 32nd Ave., Shellsburg. Three semi-wooded acres on a hilltop, 275 cultivars blooming in multiple rambling perennial beds.

Linn County Master Gardener Garden Walk

10 a.m. to 4 p.m. Saturday. Admission is $5 per adult or $10 per family. Start at any of the gardens on the Walk listed below.

  • McWherter Garden, 1610 Timberland Dr. NW, Cedar Rapids. The shade/woodland garden is an artistic presentation of plants that include more than 1,000 varieties of hostas along with perennials and tropicals.

  • Granger House Museum Garden, 970 10th St., Marion. Gardens consist of three beds featuring a mixture of vegetables, perennials and annuals commonly planted by 19th century households.

  • Stewart Farm Garden, 298 Martelle Rd., Martelle. The farm garden began as an English cottage garden, reflecting the six years they lived in Britain. The surrounding acres now include a shade garden, floral cutting garden, restored Iowa prairie, vegetable garden that includes four raised beds, and areas for fruits and vegetables preserved for year-round family use.

  • Dvorak Garden, 206 Candlestick Dr., Mount Vernon. The gardens include an eclectic mix of old and new, perennials and annuals, sun and shade, many of which have been selected to attract birds and butterflies. There also are a traditional vegetable garden, herbs, grapes and berries.

  • McKinstry Garden, 408 B Ave. NE, Mount Vernon. Peace and tranquillity prevail as you follow pathways through the garden rooms created in the perimeter of a city lot. The garden incorporates an assortment of perennials, shrubs and trees. Color and texture balance the garden’s beauty throughout the seasons.

Project GREEN Garden Tour

10 a.m. to 3 p.m. June 23. Cost is $5 for adults, kids free. Start at any garden to purchase a ticket and map. Four of the five gardens are located in Manville Heights and one garden is in the Kirkwood area.

Paul and Joan Burns, 425 Beldon Ave., Iowa City. It has a stepping stone footpath, hosta garden, many sunny perennials and a Stone City planter that showcases annual blooms.

John Chase, 419 Beldon Ave., Iowa City. The Chase dog-friendly garden also features a paved walkway, conifer trees, perennials and shrubs in the front. The fenced and gated backyard features fieldstone patio, grill and fireplace within a cedar pergola and beautiful plantings. Outdoor lighting extends the long summer hours.

Joni Jones’ garden, 516 Holt Ave. The garden displays a variety of flowers with blooms that provide a long bloom period mixed with shrubs, roses and grasses. Vines provide vertical interest and privacy. Groundcovers and mulch minimize weeds. The gardens also feature herbs, vegetables, succulents, a deck and pergola.

Randee and John Fieselmann, 933 Highwood St., Iowa City. The garden uses microclimates to maximize plant selection and limits the use of non-native plants.

Shirley and Jack Lekin, 830 Walnut St., Iowa City. The Lekins have transformed their property into a gardening Mecca. They have transformed a sunny spot to half shade with the planting of 19 trees and Canadian hemlock. Dirt was transported in to build berms and height to back flower beds. The garden is highlighted with water features and a potting shed.

Questions on gardening, land use or local foods? Contact Michelle Kenyon Brown, community ag programs manager at Linn County Extension,

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