By Ann Marie VanDerZanden,
Associate Professor of Horticulture
Iowa State University
Have you ever wondered what plants would say if they could talk? Most people probably don’t think about such things. I imagine it is probably just something horticulturists ponder. Or maybe it is just my horticulturist friends and I that think and talk about such things! In any event, if plants could talk, they would have a lot to say to you this time of year.
Lawns in particular would be quite chatty. Many of the lawns I have seen in the past few weeks are showing obvious signs of drought stress. Unless they are one of the lucky lawns with irrigation, the hot days of August really took their toll. Now is a great time to dethatch lawns to allow water to penetrate more easily into the soil. It is also a good time to do other maintenance such as fertilizer and herbicide applications to stimulate new growth and create a thicker stand of grass and to kill any weeds that have gotten established. As long as the soil temperatures stay above 50o F grass roots will continue to grow and absorb moisture and nutrients. Provided we have another long, warm autumn, and they receive adequate irrigation or rainfall, lawns may continue to grow well into the fall.
Unless a landscape has been receiving regular watering, 1-1.5 inches of water a week, the trees and shrubs will be parched this time of year. When plants are drought stressed the overall growth slows down, flowering is greatly diminished or stops all together. The obvious signs such as wilting, early fall color, and premature leaf drop are present. Making sure these plants are well-watered as they transition into winter is critical to their long-term health. Plants need to get rehydrated before the cold drying winds of winter arrive. This is particularly true of needle and broad-leaf evergreens, since their leaves persist throughout the year and are susceptible to desiccation during the winter. If a plant is already drought stressed, winter’s drying winds can be the final blow and result in death.
Once the needs of the existing plants have been addressed, it is a good time to consider adding new plants to your landscape. These new plants would have a lot to say too, given a chance. Most importantly they would want to have input on where they will be planted. Maybe they would want an opportunity to dip a root in the soil and test it out. Too sandy, too wet, too acidic, these are just a few potential soil problems that can severely limit, if not kill, a plant’s ability to thrive in the landscape. They might also like to inspect other features of their new neighborhood such as light conditions (sunny or shady), precipitation-when and how much, wind patterns, frost pockets and reflected heat.
Fortunately most plants can handle a range of environmental conditions and are somewhat adaptable. On the other hand, a few plants are not adaptable. They can be finicky as to where they are planted in the landscape. For this group of plants, it is particularly important to meet their site needs. New plants would want to know about their soon-to-be new neighbors. Slow growing plants would not do well planted near aggressive, spreading bullies. Others may be sensitive to walnut toxicity and can’t be planted near black walnut trees. Yet others may request being planted next to those whose color complements their own. Choosing the right location and appropriate neighbors is essential to the plant’s long-term success and is an important aesthetic consideration so the landscape as a whole becomes an attractive composition.
So, if plants could talk they would have plenty to say. All you have to do is listen and watch them closely. Fortunately a number of good references are available to aid with translation and to help homeowners make good plant selection decisions, as well as provide guidance on seasonal landscape maintenance. A couple of sources I suggest include the ISU Extension Gardening calendar and four relatively new ISU Extension publications on plant materials: Perennials for Shade (PM 1913), Perennials for Sun (PM 1914), Annuals (PM 1942) and Deciduous Shrubs (PM 1943). Plants listed in these publications are hardy to our zone and there is detailed information on plant characteristics and growing requirements for each plant.
These publications can be ordered by through any ISU Extension county office, on the Web at /store/ or by calling (515) 294-5247.