August marks the pivot point for New Jersey gardeners, signaling the transition from summer heat to preparation for a successful fall harvest. This month is the deadline for planting many long-season, cool-weather crops that must mature before the average first frost, which typically occurs between late October and early November in Zones 6b and 7a. Planting now ensures crops have sufficient time to develop their full flavor and size before the growing season concludes. Success requires precise timing, proper heat mitigation, and understanding which crops need a head start in the still-warm soil.
Planting Cool-Season Crops for a Fall Harvest
The backbone of a New Jersey fall garden consists of brassicas and long-season root vegetables that require 60 to over 90 days to reach maturity. These plants thrive in the cooler temperatures of September and October, but must be started in early to mid-August to develop fully. To calculate the correct planting date, gardeners must add a “short day factor” of approximately 10 to 14 days to the variety’s listed “days to maturity.” This accounts for the slower growth rate caused by decreasing daylight hours in the fall.
Brassicas, such as broccoli, cabbage, and Brussels sprouts, should be transplanted as young seedlings in the first half of August. For example, an 85-day Brussels sprout variety needs to be set out around August 1st to ensure harvest before a hard freeze. Starting these in trays allows for protected growth during the hottest weeks, preventing heat-induced stress that can cause premature bolting. Once transplanted, the warm soil encourages strong root development before the cooling trend begins.
Root vegetables like carrots, beets, and parsnips must be direct-sown now, as they do not transplant well due to their deep taproots. Carrots require about 70 days to reach a harvestable size, necessitating planting no later than mid-August to mature before a killing frost. The soil should be kept consistently moist to ensure good germination, which is challenging in the August heat. Utilizing a thin layer of shade cloth or a board placed over the row until the seedlings emerge helps keep the soil surface cool and moist, improving the germination rate.
Hardy greens, including kale, collards, and Swiss chard, are planted now for a prolonged fall harvest. These crops are cold-tolerant and often continue producing past the first light frosts, which sweetens their flavor. Unlike delicate greens, kale and chard can withstand the August heat. They should be direct-sown or transplanted early in the month to establish robust plants that provide continuous harvests into winter.
Succession Planting for Quick Final Yields
Succession planting in August focuses on crops with short maturity windows, providing a final flush of fresh produce before the end of the season. These crops mature in 30 to 45 days, making them perfect for filling spaces left vacant by harvested summer plants. The goal is to time their growth so they benefit from the warm August soil while maturing during the cooler days of September.
Fast-maturing greens like leaf lettuce and butterhead varieties are excellent candidates for August planting. These delicate leaves need protection from the intense sun to prevent bolting, which causes the plant to send up a flower stalk and turn bitter. Planting them in a location that receives afternoon shade or utilizing a 30% shade cloth draped over the bed will mitigate high temperatures.
Quick-Maturing Vegetables
Radishes are the fastest crop available, often ready for harvest in just three to four weeks. Their rapid growth cycle allows for multiple small sowings throughout August, providing a continuous supply. Bush beans, which mature faster than pole varieties, can also be planted in early August, but this is the final opportunity. Look for varieties with a short 50-to-60-day window to ensure the pods have time to set and ripen.
Herbs and Moisture
Certain herbs, such as cilantro and dill, are quick to mature and can be sown now for a late-season yield. These herbs are prone to bolting in the summer heat, but they perform better when planted in late August as the nights begin to cool. Consistent moisture is paramount for all these quick-yield crops, as high August temperatures and fast growth deplete soil water reserves rapidly.
Preparing the Garden with Non-Edible Plantings and Soil Amendments
Beyond the immediate goal of a fall vegetable harvest, August is a strategic month for long-term garden health. This is the ideal time to incorporate structural improvements and sow non-edible plants that benefit the soil and provide early spring color. Focusing on soil health now ensures the garden is ready for a strong start next spring.
In beds that have finished producing summer crops, sowing a cover crop is the most beneficial action for soil health. Planting buckwheat, clover, or winter rye will prevent soil erosion and suppress weeds over the dormant season. As the cover crop grows, its roots break up compacted soil and scavenge residual nutrients, preventing them from leaching away. These plants are then cut down and incorporated into the soil in spring, adding organic matter and improving soil structure.
The warm soil in August provides an excellent environment for the root establishment of perennial plants. Many perennials, such as iris and peonies, can be successfully divided and transplanted this month. Dividing the root ball and replanting segments allows the roots to anchor themselves and recover before the ground freezes, which increases their bloom potential for the following year.
August is the time to finalize plans and orders for spring-blooming bulbs like tulips and daffodils. While these bulbs are typically planted in September or October after the soil has cooled, ordering them now ensures the availability of desired varieties. This planning step completes the cycle of the gardening year by setting the stage for color in the earliest days of the following spring.