Tips for Tree and Shrub Care after a Dry Summer

Wednesday, October 27, 2021

After a dry summer (and a dry spring) it's important to continue to water your trees and shrubs until the ground freezes. Here are some tips from tree experts to help you prepare your landscape for winter.

From the Morton Arboretum about how to water into autumn:

This has been another difficult year for watering. For the first time in many years, spring was very dry. Summer was not much better. July and August came roaring in with extreme heat and inadequate rainfall in many areas. As autumn comes on and the temperatures cool (we hope), there is often the assumption that the growing season is over and we can put the garden hose away. That really is not the case, even in a 'normal' year. "Should we be watering now? Because the rain has been so inconsistent, we really need to go out and observe the soil in our own yard. One good rain will not get us off the hook. If the soil is dry, we should be watering. Watering is all about what the plant needs now. The weather is our guidepost, not the calendar.

With autumn, we will start to see plants go dormant, and perennials will even start to die back. The root systems of all plants are still quite active, and watering will help to keep them in good health. You can continue to water until the soil freezes. Pay special attention to evergreens. Since they retain their needles year-round, they can continue to lose water through those needles. Make sure that all evergreens go into winter fully hydrated. If you are planting bulbs like tulips or daffodils, they will also need to be watered. When bulbs are planted, they need to grow a root system in the fall. That can be difficult to do if the soil is too dry.

Other areas that would need special attention are newly seeded or sodded lawns and any newly planted trees, shrubs or perennials. All these plants will need a good supply of water to help them become established. Newly planted trees and shrubs do not need to be watered every day. That is good for puppies, but not for trees. Water as needed. Check the soil to see how dry it is. Remember that on a newly planted tree there will be a limited root ball. Apply the water to the root ball area.

We need to modify our watering practices based on the rainfall we get this autumn. Consider purchasing a rain gauge for your yard so you can accurately determine how much rain you are receiving. Storms can be deceiving. A heavy storm may give the impression that a lot of rain fell, but a rain gauge will let you know how much rain really fell. Ideally for most established plants we want to deliver an inch of water per week. If the rain provides half an inch, we need to provide the other half. Try to do the watering all at once so we get a nice deep watering. Sprinkling a little bit everyday does not give the plant the water it needs, and it promotes fungal diseases, not to mention what it does for your water bill.

Mulching Tips

Applying mulch around trees can help retain moisture. However, it's important to apply the mulch around the tree in a donut shape and NOT in a volcano shape. This illustration from the Morton Arboretum explains more.

Use your Fall Leaves!

By Naperville Park District staff member Tiffani Picco, Park Specialist II and an ISA Certified Arborist

Leaves are an excellent source of nutrients for trees, shrubs, lawn and garden. Think about this: nobody goes out and rakes all the leaves out of the natural woodlands. Those leaves are an essential part of the ecosystem, providing food for earthworms and beneficial microbes, and providing shelter for insects and small animals. They break down and provide all of the nutrients needed for those trees to be healthy. Nobody rakes up the leaves, and nobody goes out and spreads fertilizer either. The leaves provide those needed nutrients. They can do the same for your yard!

If you don't have a leaf shredder, leaves on your lawn can be mowed over several times to break into small pieces. In the spring, those small pieces will decompose rather quickly and provide nutrients as your grass begins to grow, which will reduce or eliminate your need to add fertilizer. If you have a large amount of leaves, those are perfect for adding to the compost pile or vegetable garden, or using as mulch around some of your tender perennials or shrubs. Similar to wood mulch, you can spread shredded leaf mulch 2-4 inches thick, but be careful not to pile against shrub stems and tree trunks. Shredded leaves are key, as they will break down faster but also allow water to penetrate to the soil below them. Layers of full leaves tend to stick together and provide a barrier, which will not help the roots of your plants.

Some people have a tremendous amount of leaves, and some will need to go in yard waste bags to be hauled away. But consider using what you can of those leaves: your trees and plants will thank you!

Why is the fall color late this year (in 2021)?

How are the drought conditions related to fall color displays? A recent article in the Daily Herald explores the factors involved in the timing and intensity of autumn leaf color. According to the article, drought conditions can cause the colors to be delayed and to be more muted. Tree specialists from the Morton Arboretum say that "cool, but not freezing, nights and sunny days generally bring out the best fall colors."

A technical report from Bartlett Tree Experts explains the chemical processes involved in developing leaf color and how weather affects the colors.

Naperville's Trees

At the Naperville Park District, we care for trees in the parks. Our park maintenance staff monitors tree health and on average, plants more than 300 new trees each year. The District's 136 parks include both shade trees and ornamental trees in landscaped areas and trees that grow naturally in large, forested areas, as in 224-acre Knoch Knolls Park.

Any trees that are in the parkways (right of ways) between homes and the roadways within incorporated areas in the City of Naperville are part of the City's urban forestry program, and not part of the Park District. Learn more about cost sharing and care for parkway trees at www.naperville.il.us/residents/our-urban-forest/.