While spring is the traditional planting season in Iowa, late summer and early fall (mid-August to early October) is an excellent time to plant many landscape plants. Below is advice on fall planting of trees, shrubs, perennials, annuals, spring-flowering bulbs, lawns, and vegetables.
August through early November is an excellent time to plant deciduous trees and shrubs. Evergreen plants, such as pine and spruce can be planted from mid-August through September. (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.)
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.
More Information on Planting Trees and Shrubs
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, iris, 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.
More Information on Planting Perennials
- Late Season Perennial Flowers
- Flowering Plants for the Late Summer Garden
- When to Divide Perennials
- Which perennials can be divided in late summer?
- Perennials for Sun
- Perennials for Shade
- Perennials for Shady Areas
Annuals are a great way to add variety and color to the landscape and containers. As temperatures cool in late summer into fall, many of the summer annuals like marigolds, coleus, and impatiens are looking “tired.” These annuals can be replaced by cool-season annuals that do well in the cooler temperatures of fall.
Cool-season annuals are annual plants that prefer cool temperatures, growing best in spring or fall. Many are tolerant of a light frost, often surviving down to 28°F or sometimes even 25°F with little damage to flowers or leaves. They are great additions to containers and garden beds in the shoulder seasons to add color late into autumn. For the fall season in Iowa, cool-season annuals can be planted mid-to-late September. They can remain in the garden until they are killed by cold temperatures. For many of these plants that is typically mid-November to early December in much of Iowa.
More Information on Planting Annuals
- What cool-season annuals do well in Iowa?
- What do I do with cool-season annuals when winter arrives?
- Certain cool-season annuals are sometimes grown as perennials. Can I expect these plants to come back each year?
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.
More Information on Planting Bulbs
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.
More Information on Seeding Lawns
- Seeding a New Lawn
- Establishing a Lawn from Seed
- Overseeding a Lawn
- Sodding a New Lawn
- Fall Tips to Ensure a Healthy Green Yard in the Spring
Several vegetables can be planted in late summer for a fall crop. For a fall crop, plant beets, carrots, Swiss chard, kohlrabi, and kale in early to mid-August, plant leaf lettuce and spinach in late August to early September, plant radishes from mid-to late September, and plant garlic from October to early November.
Due to hot, dry soil conditions, seed germination in late summer is often rather poor. To promote seed germination, plant fall vegetables when the soil is moist after a rain, sow the seeds slightly deeper than spring plantings and lightly water the row after the seeds have been sown.
Lettuce seeds are sensitive to extreme heat. To achieve good lettuce seed germination, check the weather forecast and sow the seeds when a prolonged period of mild weather is predicted.