Summer is tough on landscapes. High temperatures, high humidity and dry conditions can leave many gardens looking ragged by September.
Fortunately September is a great time to repair summer's damage and get gardens back into good condition before winter. Good landscape practices for late summer and early fall include dividing perennials, controlling weeds, fertilizing turfgrass and watering trees and shrubs.
Divide Perennials
September is a great time to divide perennials that bloom in spring and early summer. Look for plants that have crowded stems, fewer blooms or a dead section in the center of the crown. These symptoms indicate it may be time to divide your plants. Dig up entire plants and tease apart the root systems. Cut away old, bare root sections before placing the plants back into the ground.
Weed Control
Fall is the best time of year to control perennial weeds such as dandelions, ground ivy and wild violets, and if only a few weeds are present they can often be pulled or dug up by hand.
In fall, plants begin moving carbohydrates in the leaves to the roots for winter storage. Herbicides applied at this time are transported more readily to the roots, killing the entire plant instead of just the parts above the soil surface. Herbicide spot treatment, or spraying individual weeds, saves money on chemicals and limits chemicals in the environment when only a few weeds are scattered throughout the lawn. Ready-to-use liquid products can be kept on hand for a quick application when weeds are found. For more severe weed problems, a broadcast herbicide application can be made to larger areas.
Many products are available for broadleaf weed control, including formulations of 2,4-D, quinclorac or triclopyr. These products can be used in turf areas and won't damage underlying grass, but use caution around landscape beds since accidental spraying or spray drift can damage shrubs and ornamental plants. Quinclorac is particularly effective at controlling wild violets.
A granular post-emergent herbicide may be applied with your September fertilizer application. Apply granular herbicide to damp grass to ensure the herbicide will stick to dandelion leaves and become absorbed. It's best to apply after irrigation or in early morning. As with all chemical applications, be sure to read and follow all directions on labels and use personal protective equipment.
Fertilization
Early September is the time for the first fall lawn fertilization, providing nutrients turfgrasses need to grow actively again after summer's heat and replace leaf blades damaged or killed by insect or disease activity.
However, keep fertilizer away from trees and shrubs because nutrients will encourage new growth. These tender new shoots or roots may not have time to harden off properly and could be damaged by early cold conditions.
Watering
Finally, watering plants in fall is an essential practice to rehydrate them before winter's dry, cold conditions arrive. Typically landscapes require one inch of water per week, if there is not a similar amount of rain. When watering trees and shrubs, apply that inch in one day so that you moisten the deeper layers of the soil.
Adjust your sprinkler system for fall conditions. In the summer, irrigation systems run more frequently and for longer periods because the weather is hot and dry. But in the fall, temperatures are cooler, so watering should be reduced.