There are four things every homeowner should do for their yard this fall. It can be a busy time and invariably there will be tasks left undone when the snow starts falling. These are things you should not leave undone.
The application of fertilizers in late fall can improve the vigor of turf, shrubs, trees and other perennials. The late fall fertilization increases the plant’s carbohydrate reserves which help resist winter injury and improve the plants’ resilience next year. Another benefit of late fall fertilization is an increase in root mass. A soil test will tell you for sure, but if you have been diligent in applying a fertilizer containing phosphorous and potassium, you likely only need to apply light nitrogen this fall. In fact, you may have adequate phosphorous and potassium for several years. A basic soil test will let you know.
Perennial Weed Treatment
Perennial weeds are those that grow back from the roots each year. The classic example is field bindweed. Other common ones are dandelion, quackgrass, mallow, plantain and Canada thistle. These also grow from seed, but the seedlings can be controlled easily year-round. Established plants often require proper timing. In general, fall is the best time to hit them hard. After a hard frost, the treated herbicide is pulled deep into plant tissues as it retracts resources from the outer leaves in preparation for winter. The best time for this treatment is likely to be the first part of October.
Deep Water Trees
All trees should have one last deep watering in October. Evergreens continue to transpire during winter. It is especially important they have access to deep moisture, particularly if we end up with a dry winter. You can let a hose run on a slow stream, periodically moving it around the dripline. Small trees need only about 40 minutes. Larger trees require more water. It may take 4-5 hours or more to adequately wet the soil around your tree.
Look for Yellow Leaves
Not long after starting work in Idaho I did a series of articles on the management of iron chlorosis in our landscapes. This is by far the most common ailment I see on site visits. As I go to homes and recommend solutions to problems, nearly without fail I end up also discussing iron deficiencies that are evident throughout the yard. We have iron but our calcium-rich, high pH soils keep it unavailable to many plants. Iron deficiency is expressed as a yellowing/lightening of the leaf tissue. In more advanced cases the leaf margins will die and dry up. Iron chlorosis limits plant’s ability to photosynthesize and results in weakened and stressed organisms. Pay attention now to what your yard is telling you. Make note of the yellow, sickly-looking plants. It is likely iron deficient. It will need an iron supplement next spring. Your first line of defense is EDDHA iron chelate. It provides the simplest, most effective method to treat iron deficiency. See https://www.uidaho.edu/extension/county/franklin/horticulture for greater detail.