Planting tomatoes in August is entirely possible, but success depends on strategic planning and choosing the right varieties for a late-season harvest. This late start is often called a fall crop, and it allows gardeners in many regions to extend their fresh tomato season well into autumn. Achieving a harvest requires selecting varieties that mature quickly and providing the focused care necessary for plants establishing themselves during intense summer heat.
Determining Your Local Growing Window
The most important factor in planting tomatoes in August is the number of days remaining until your area’s average first hard frost. You must first find this date for your specific location, which is when the air temperature typically drops below 32°F and will certainly kill tender plants like tomatoes. The key calculation involves comparing this date to the tomato plant’s Days to Maturity (DTM), which is the time it takes from transplanting the seedling into the ground until the first fruit is ready to pick. To ensure a successful harvest, the variety’s DTM must be significantly less than the number of days between your August planting date and the average first frost date. For instance, if your frost date is 90 days away, select varieties with a DTM of 60 days or less to allow time for fruit set and ripening. This late-season planting is typically most feasible for gardeners in southern and western states with long, mild autumns, while northern gardeners must be much more precise with their timing and variety selection.
Choosing the Right Tomato Varieties and Starts
For an August planting, it is necessary to use established transplants, or “starts,” rather than sowing seeds directly into the ground. Starting from seed in August will not allow enough time for the plant to mature and produce fruit before the season ends. When selecting these starts, prioritize varieties with the shortest DTM, ideally those listed at 50 to 60 days. Focusing on fast-maturing types ensures the plant puts its energy into producing fruit quickly rather than prolonged vegetative growth.
Excellent choices include:
- ‘Subarctic’ (around 50-55 days)
- ‘Early Girl’ (50-60 days)
- ‘Sungold’ (57 days)
- ‘Juliet’ (60 days)
You should also look for determinate tomato varieties, which grow to a predetermined size and set most of their fruit at once, making them ideal for a short growing window. Indeterminate, or vining, types continue to grow and produce until frost, but they may dedicate too much time to vine development before setting fruit this late in the season. Cherry and grape tomatoes are often the most reliable choices for a fall crop because their smaller size naturally correlates with a faster DTM. These smaller fruits require less time and energy to reach maturity than large slicing or beefsteak varieties.
Essential Care for August Plantings
August-planted tomatoes require a distinct care regimen that addresses the contrasting conditions of late summer heat and the need for rapid growth. Due to the intense August sun and heat, deep, consistent watering is important to prevent heat stress and blossom end rot. Water deeply a few times a week, ensuring the soil remains moist but not waterlogged. Apply a layer of mulch to help keep the root zone cool and conserve moisture.
The late-planted crop needs a steady supply of nutrients to accelerate fruit production. Apply a balanced fertilizer at the time of transplanting, then follow up with additional feeding during the flowering and early fruit-set stages. Providing consistent nutrition encourages the plant to set fruit quickly, rather than expending energy on vegetative growth. Ensure good airflow by pruning any lower leaves that touch the soil to minimize the risk of fungal diseases like blight, which thrive in humid late-summer conditions.
Expected Harvest Timeline
With a successful August planting of 50-60 DTM varieties, expect your first ripe fruit harvest in late September or early October. This crop will not produce the same volume as a full spring-to-fall planting, but it will extend your season with a rewarding flush of autumn tomatoes. Once the daytime temperatures begin to cool, the plant’s energy shifts toward ripening the existing fruit.
As the days shorten and the average first frost date approaches, you may still have many green tomatoes on the vine. To salvage this remaining crop, harvest all mature green fruit before the first hard frost kills the plant. These mature green tomatoes can be brought indoors and stored in a cool, dark place to ripen off the vine, providing fresh tomatoes for several weeks beyond the end of the outdoor growing season.