Microclimates are Important to Planting in Southeast Iowa

Microclimates are Important to Planting in Southeast Iowa

Spring is coming, the nursery catalogs have arrived, and you’re getting anxious to plant something! I’ve found that so many of the catalog descriptions claim your favorites will grow in Zone 5, and here we are in the middle of Zone 5, and yet you’ve probably had some pretty serious plant mortality because of the severity of the past two winters.

When we moved to Iowa City nearly a half century ago, our more established neighbor had an attractive tulip tree that was about five years old. Even though we were outside this species’ native range, we planted one also. But only a few years later, both died during a harsh winter. Frustration city!!! But this lead me to pay closer attention to the very local climatic clues like snowmelt patterns, winter wind sweep patterns, shadow patterns, dessication patterns, etc., and which species were doing well or poorly in these areas.

It is especially important to get microclimate planting zones correctly identified because part of our conservation efforts are aimed at uncommon species, which we are trying to support on the landscape. These were often sparse on original landscapes, even before the plow, because they only thrived in select little patches with particularly favorable microclimates.
The key lesson here is that our eastern Iowa landscape is actually a mosaic of many little patches of different microclimates, which collectively do average out as Zone 5; but specifically, where you are planting, the area may be as mild as Zone 6 (central Missouri), or as frigid as Zone 4 (southern Minnesota). So here is “Lon’s Observations of Microclimate Effects In Southeast Iowa.”

I hope this will help you select the best plants for your property; or at least avoid the worst choices if you are more of a risk-taker. So look more carefully at the clues your property is offering, and here are some guidelines of what to look for.

4 thoughts on “Microclimates are Important to Planting in Southeast Iowa”

  1. Thanks so much!
    We used to live on the western edge of Iowa City, where we would routinely see 20 below zero and 20 mph winds when a winter front came through. Then we moved to the east bank of Coralville Lake, overlooking the dam, and it is stunningly milder. I was wondering about microclimate versus global warming for the difference.
    What a superb description and explanation of what we see all about us.

    1. Hello Hetty!

      Yes, the east side, often downwind of the Lake probably does have a very narrow, milder strip near the shore. Understanding the timing of climate change based on temperature records requires statistical analysis too complex for me and only yields probabilities. But plants are 100% real, and cannot migrate or hibernate like animals, so they faithfully respond to climate change. Around the late 1980’s, young trees started surviving here in places that were previously beyond their species’ range. For example, there are now 20-30 year-old tulip trees established around here, some even on sheltered but north-facing slopes. These trees are integrating daily weather, the net product we label climate, and this is more meaningful to me than mathematically integrating long-term temperature data because it also shows some of the results of climate change. Where you live now, you are seeing the combined effects of a milder, very local microclimate plus our regional climate change.


  2. kathleen renquist

    Thanks for the information as it supports my trial and error plantings. Siberian iris really like to be on the north side of the house where winter wind and cold hit them smack in the face – if they had faces…. Whereas, my Blue Flag iris likes the east side where it is more protected and does not mind being hot in the summer. Two very similar species, two very different microclimates at the same address in Iowa … North side of a slope vs south side of the same hill produce later blooming bluebells as well.

    1. Hello Kathy!

      Siberian iris really is a subpolar species. Where I worked in Alaska this iris grew on the edges of swamps. My fellow restorationist, Dick Baldwin, collected seed on the Kamchatka Peninsula in western Russia and when he grew it out near Anchorage, side by side with the local iris, we could not tell them apart. Here in Iowa, they bloom a month or more ahead of those in their ancestral homeland, and as you have observed, are well adapted to our coldest microclimates, as long as there is plenty of soil moisture. Blue flags, by contrast, are native right here and also a wetland species.


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