Evergreens can lose water this month

It is easy to forget about watering during the colder weather in November, but recently planted evergreens should not go into winter under stress from being too dry, which will increase the chance of winter burn. Evergreens planted over the last three years should be watered as needed this month if conditions are dry.

In winter's freezing temperatures and wind, evergreens can lose moisture from their leaves faster than their roots can replace it. This is particularly a problem once the soil is frozen, especially if the soil had little moisture in fall.

Make sure the root balls of evergreen trees are thoroughly moistened by applying water directly at the base of the plant. The dense branches of evergreen trees can shed rain water from a sprinkler away from the root ball. 

Autumn is a good time to have your garden soil tested to determine how best to manage it and what fertilizers to use. Make a composite sample from a few areas in the bed and send in for testing. If your garden is large, it is a good idea to break the garden into zones and test each separately.

Soils in the Chicago area tend to have adequate amounts of phosphorus, so in these situations choose fertilizers that do not have phosphorus in them or very small amounts.

Prepare your hybrid roses for winter after there have been two to three hard freezes, when temperatures drop to the teens. These typically occur in late November at the Chicago Botanic Garden in Glencoe.

First, clean up clean up and remove any rose leaves that have fallen if you had problems with black spot, a common fungal disease. The spores that spread this disease can overwinter on infected foliage.

Cut back the rose canes to about 18 inches and mound the roses to a height of 12 to 15 inches with compost or mulch. Do not use grass clippings, which will mat down and hold moisture around the plants. Hardy shrub roses do not require this special treatment for the winter. 

Clean out your gutters once all leaves have fallen. Leaves will clog up the gutters and will be much more difficult to remove once they have frozen.

• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.