August marks a significant transition in the garden, moving away from the peak abundance of summer and preparing for the cooler temperatures of autumn. This period represents a crucial window for strategic second plantings. By sowing specific crops now, gardeners can ensure a continuous harvest well past the summer months and into the late fall. Success in August planting relies on understanding which vegetables thrive in the decreasing daylight hours and which require the residual summer warmth for establishment.
Quick Late Summer Harvests
For gardeners seeking nearly immediate returns, August provides the perfect opportunity to sow fast-maturing crops that will be ready for harvest within 30 to 60 days. These vegetables utilize the remaining high light intensity and warmth to germinate and establish quickly. Radishes are a prime example, often maturing in as little as three to five weeks from the date of direct seeding, providing a quick root crop. French Breakfast varieties are typically ready in 22 to 30 days and require planting about half an inch deep. Thinning aggressively once sprouted ensures proper root development.
Loose-leaf lettuce varieties, which can be harvested by the cut-and-come-again method, are also ideal for a rapid turnover. Unlike head lettuce, loose-leaf types are less prone to bolting in the lingering heat and can be ready in 30 to 40 days. Bush beans with a shorter maturity window can be planted in early August, offering a final flush of pods before the first frost, usually maturing in 50 to 60 days. Cilantro also benefits from a late-summer sowing, as it germinates well in the warmth but prefers to mature in cooler weather, which helps prevent premature bolting.
Starting Seeds for Fall and Winter Production
Planning for a substantial autumn harvest centers on cool-season crops that require a long growing period before the light diminishes significantly. This requires calculating backward from the average date of the first expected frost in your region. Brassicas—a family that includes broccoli, cabbage, Brussels sprouts, and kale—are champions of the cool-season garden and need to be started from seed or transplanted in August.
These crops typically require 60 to 90 or more days to reach a harvestable size, meaning they must establish their root systems and foliage during the final weeks of summer. For instance, many broccoli and cabbage varieties need to be transplanted four to six weeks before the first frost to allow for sufficient head formation. Starting them early ensures that the plants are large enough to withstand the slower growth rates that occur once the day length shortens.
Hardy leafy greens like spinach and Swiss chard also benefit from an August start. While spinach can be harvested in 30 days for baby leaves, a larger, more cold-tolerant plant is desired for extended fall harvests. Selecting cold-hardy varieties, such as ‘Lacinato’ kale, is important. These varieties are bred to improve in flavor and sweetness after exposure to light frost, a process known as cryoprotection.
Root Vegetables and Bulbs for Autumn
August is an opportune time to sow root vegetables that sweeten considerably after a light frost. Carrots, beets, and turnips are classic choices for this late-season planting. These taproot vegetables demand distinct soil preparation, requiring deeply cultivated, loose, and rock-free soil to allow for straight, uniform growth. The soil should be loosened to a depth of at least 12 inches, and any large debris must be removed, as obstructions can cause the roots to fork or grow crookedly. Carrots and beets generally take 60 to 80 days to mature, aligning their harvest time with the arrival of cooler weather. Turnips are faster, with some varieties ready in 5 to 10 weeks. Late August to early September is the time to plant overwintering onion sets and garlic cloves, which require this early start to establish roots before the ground freezes for a successful harvest the following spring or summer.
Dealing with August Heat and Soil Preparation
The primary challenge for August planting is the lingering summer heat, which can stress young seedlings and cause seeds to fail. To mitigate this, new seedlings, especially heat-sensitive leafy greens, often require temporary shade cloth protection during the hottest part of the afternoon. Using a shade cloth that blocks 40 to 50 percent of the sun’s intensity can reduce soil and air temperatures, preventing leaf scorch.
Increased watering must be done strategically, applying water deeply and infrequently, ideally in the early morning or late evening, to encourage deep root growth and minimize evaporation. Applying a layer of organic mulch, such as straw or shredded leaves, two to four inches deep around plants helps regulate soil temperature and retain moisture. Before planting, incorporating compost into the garden beds ensures that nutrients are readily available and improves the soil’s structure, enhancing its water-holding capacity for the demanding fall growth period. Pests that thrive in the late summer heat, such as cabbage worms and flea beetles, also become a management concern, sometimes necessitating the use of floating row covers to exclude them from tender new plants.