While spring is the traditional planting season in Iowa, late summer/early fall is an excellent time to plant trees, shrubs, perennials, and spring-flowering bulbs. Late summer is also the best time to establish a lawn from seed.
Mid-August to mid-September is the best time to seed new lawns and overseed existing lawns in Iowa. A late summer seeding has several advantages over spring seeding. The seeds of cool-season grasses germinate quickly in the warm soil of late summer. The warm days and cool nights of early fall promote rapid turfgrass growth. The growing grass also has less competition from weeds as few weed seeds germinate in late summer or fall.
Trees and Shrubs
Mid-August through September is an excellent time to plant pine, spruce, and other evergreens. (Evergreens planted in late October or November may not have adequate time to become established before the onset of winter and could be subject to desiccation injury and death.) Deciduous trees and shrubs can be planted from August through early November.
Water newly planted trees every day for 3 or 4 days and then gradually reduce the frequency of watering. When watering, slowly apply water to the rootball and the surrounding soil. A thorough watering every 7 to 10 days (in dry weather) should be sufficient 3 to 4 weeks after planting. Continue watering until the ground freezes.
Late summer/early fall is an excellent time to plant many perennials. It is also a good time to move or divide perennials, such as peony, daylily, garden phlox, and oriental poppy. Perennials planted in late summer or early fall should be mulched with several inches of straw, pine needles, or other materials in late fall. Mulching helps prevent repeated freezing and thawing of the soil that may heave plants out of the ground. Drying of the exposed plant crowns and roots can cause severe damage or death.
October is the ideal time to plant tulips, daffodils, and other spring-flowering bulbs. Plant bulbs in groups or clusters to achieve maximum visual impact. Bulbs planted individually or in single rows are generally not as effective. Spring-flowering bulbs can be planted as late as December if the ground is not frozen.
Late summer/early fall is time for the gardener to enjoy the fruits of their labor over the past several months. It’s also time to plan and plant for the future.