August serves as the bridge between the intense heat of summer and the cooler, more productive days of fall. While it may seem late, this month is the final window for planting a successful autumn harvest. Success relies on careful planning, primarily by calculating the “Days to Maturity” for chosen crops backward from the average first frost date in your region. This precise timing ensures that plants reach a harvestable size before the cold weather permanently halts their growth. August is also about strategically utilizing garden space left vacant by harvested summer crops. By acting decisively, you can maximize your garden’s output, setting the stage for a prolonged harvest well into October and November.
Vegetables for a Fall Harvest
Longer-term, cool-weather vegetables that require over 60 days to mature must be started in early to mid-August to benefit from the remaining warmth. These crops, many of which are Brassicas, develop a sweeter flavor profile after being kissed by a light frost. Cabbage, broccoli, cauliflower, and Brussels sprouts require foresight, needing 10 to 16 weeks from seeding to harvest depending on the variety.
When calculating planting dates, add an extra two weeks, often called the “fall factor,” to the days to maturity listed on the seed packet. This adjustment accounts for the slower growth rate as the days become progressively shorter and cooler.
Root vegetables also thrive when sown in August for a fall harvest, including carrots, beets, and rutabagas. Carrots, which take 8 to 12 weeks, benefit from being planted in the late summer when the soil temperature begins to moderate, as high heat can inhibit germination. Rutabagas take about 90 days, and their flavor improves after a few frosts. Bush beans and shelling peas can also be planted in early August, as they mature in about 60 days, yielding a crop right up until the first light frost.
Quick-Maturing Crops and Succession Planting
August is the ideal time to practice succession planting, which involves filling the gaps left by spent summer plants with fast-growing crops that mature in 30 to 60 days. This technique maximizes productivity. Leafy greens are the backbone of this late-season strategy, with varieties of lettuce, spinach, and Swiss chard being perfect candidates.
The challenge is preventing these cool-season greens from bolting, or prematurely going to seed, due to the lingering summer heat. To combat this, they should be sown in areas that receive afternoon shade or utilize shade cloth. Radishes are one of the fastest options, ready for harvest in as little as 30 days, making them perfect for tucking into small spaces.
Cilantro and dill are quick-growing herbs that also benefit from an August sowing, as the cooler autumn temperatures prevent the rapid bolting that plagues them in summer. To ensure a continuous supply of these fast crops, sow small batches of seeds every two weeks until about six weeks before the first expected frost. This staggered planting ensures that as one batch is harvested, the next is already reaching maturity, extending the availability of fresh greens and roots.
Flowers and Spring Preparation
Gardening in August extends beyond vegetables to tasks that prepare the landscape for the following spring and winter. Spring-flowering bulbs, such as daffodils, tulips, and hyacinths, should be ordered now, though they will typically be planted from late August through early fall. Planting them a few weeks before the ground freezes allows them time to establish roots for next year’s bloom.
Certain perennials and biennials, including foxglove and hollyhock, can be sown from seed directly into the ground during late summer. This timing allows the seeds to germinate and establish a root system before winter, ensuring they flower vigorously in the subsequent spring or summer. August is also a practical time to sow cover crops like winter rye or buckwheat in garden beds that have been completely harvested. These crops protect the soil from erosion, suppress weeds, and enrich the ground with organic matter and nutrients when tilled under in spring.