Planting tomatoes in July is common for gardeners seeking to extend their harvest or who have experienced a late start. Although the peak planting window has passed, warm soil and long summer days still offer an opportunity. Success relies on understanding the interplay between the local climate and the tomato plant’s biological needs. This requires a practical approach to variety selection, planting method, and ongoing care to ensure the plants mature before the autumn frost.
The Short Answer: Why July Planting is Possible
Planting tomatoes in July is possible, but success hinges on calculating the difference between the expected first fall frost date and the plant’s “days to maturity.” Tomatoes are sensitive to cold and require sufficient frost-free days to set fruit and ripen. This period is determined by counting backward from the average date of the region’s first autumn frost.
The “days to maturity” listed on a plant tag indicates the number of days from transplanting a seedling until the first ripe fruit. For a July planting, this number is the limiting factor, requiring selection of a variety that can complete its reproductive cycle within the remaining growing season. Warmer climates, such as USDA Zones 7 and above, offer a greater chance of success and a wider selection of varieties. Even in cooler zones, choosing a fast-maturing variety can still provide a harvest before the season ends.
Choosing the Right Tomato Varieties for Late Planting
Success with late planting depends on selecting varieties with a short maturity window. Look for varieties with a “days to maturity” of 70 days or less, with the most reliable options falling closer to the 50 to 60-day range. This short window is needed to guarantee a harvest before the season ends.
The distinction between determinate and indeterminate varieties is important for July planting. Determinate varieties, often called “bush” types, grow to a specific size and set most of their fruit within a short period. They are preferred for a shortened season because they channel energy into a single, concentrated harvest, which is ideal when racing against the calendar. Fast-maturing examples include ‘Subarctic Plenty’ (around 45 days), ‘Early Girl’ (bush version, around 55 days), and cherry or grape tomatoes like ‘Gold Nugget’ (around 60 days), which naturally mature quickly.
Essential Planting Techniques for Mid-Summer Success
Given the late date, plant established seedlings, or transplants, rather than starting from seed. Starting with a plant six to eight weeks old saves time on the overall maturity calculation.
These transplants must be planted using deep planting: remove the lower leaves and bury the stem deep in the soil. This allows the buried stem to develop an extensive secondary root system. Deep planting encourages robust root growth, which helps the mid-summer plant handle peak heat stress.
To mitigate heat shock immediately after transplanting, amend the soil with organic matter like compost to improve water retention. An immediate, deep watering is also necessary to settle the soil around the roots and help the plant adjust to its new environment.
Mid-Season Care and Maximizing the Late Harvest
Late-planted tomatoes face intense summer conditions, making attentive mid-season care necessary. Consistent and deep watering is important during the heat of July and August, as inconsistent moisture can lead to physiological disorders like blossom end rot or flower drop. Keep the soil consistently moist but not saturated, often requiring one to one and a half inches of water per week.
Apply a thick layer of organic mulch, such as straw or shredded leaves, around the base of the plant, keeping it a few inches away from the stem. Mulch serves the dual purpose of keeping soil temperatures lower and reducing water evaporation. If daytime temperatures consistently exceed 90°F, temporary shading with a 30% to 50% shade cloth during the hottest afternoon hours can prevent flower drop, which occurs when high heat interferes with pollen viability.
To further encourage a timely harvest, late-season plants benefit from selective pruning to focus the plant’s energy on ripening existing fruit. Removing the growing tip of the main stem, a practice known as “topping,” slows vegetative growth and redirects carbohydrates toward fruit development. Any new flowers that appear late in the season, approximately 30 days before the expected first frost, should also be removed, as these fruits will not have enough time to reach maturity.