Selecting Varieties for Growing in the Southeast US

Variety selection is paramount to success in any growing region, and the Southeast US presents unique growing challenges such as heat, humidity, and many pests and diseases. Through our regional trialing program, plus feedback from breeders, growers, and customers, we trial and select varieties that perform well under these conditions.

map of US southeast
For the purposes of this article, we define the Southeast US as the following states: Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, and Virginia.

Pest & Disease Pressure

Hot, humid conditions promote disease and pest development, and can pose a significant barrier to successful production. We recommend contacting your local cooperative extension service for help with identification and management strategies for pests and diseases in your area.

Variety selection is very important for mitigating risk of crop loss to common diseases. We select and trial varieties for strong disease packages and indicate disease resistances in our product descriptions.

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Heat Tolerance

heat tolerance symbol
Filter your web searches by "heat tolerant" and look for the heat tolerant symbol on products in the Johnny's catalog.

Our Heat Tolerant symbol indicates a variety that will perform relatively well (compared to other varieties within its crop group) when exposed to especially hot weather. Johnny’s Research Team assigns the Heat Tolerant symbol to individual varieties within crop groups that traditionally do not perform well in the heat (as opposed to warm season crops that thrive in the heat); we do this to guide growers to more suitable options. In addition to trialing heat-tolerant varieties of cool-weather crops such as broccoli, cauliflower, and lettuce, we also seek out highly heat-tolerant versions of warm weather crops; for example, tomatoes that demonstrate the ability to set fruit even under heat stress.

Learn more about what makes a variety heat-tolerant—including examples from cool-loving and heat-loving crops—in our article, Selecting Varieties for Heat Tolerance.

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Day Length

Day length can affect maturation in some crops, such as bulbing in onions, garlic and flowering among some cut-flower crops like sunflowers. This phenomenon is called photoperiodism and describes how plants respond to the relative lengths of lightness and darkness plants experience each day. Look for information in product descriptions that indicate a variety’s suitability for short days.

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Suggestions for Common Crops in the Southeast

Beans

We look for bean varieties with strong heat tolerance and disease resistance. Common disease pressures in the Southeast include rust, angular leaf spot, Anthracnose, bacterial blights, and root rots (Rhizoctonia and Pythium). Plants with an upright plant habit reduce soil contact that can lead to disease. Time plantings to avoid peak heat and choose varieties adapted to short production windows to enable harvest before late-season stress peaks.

Broccoli

Mini broccoli (a.k.a. sprouting broccoli) is more tolerant to heat and fluctuating temperatures than standard heading broccoli. Mini broccoli is less prone to maladies associated with heat such as brown bead and head rot. If there is a really hot stretch of weather, a harvest may be lost. But, because the plants keep producing more shoots, subsequent harvests will be fine once the weather cools.

Sweet Corn

For sweet corn in the Southeast, prioritize strong seedling vigor, reliable tip fill, and resistance to common regional disease pressures such as common rust, northern corn leaf blight, maize dwarf mosaic virus, and Stewart’s wilt. Among Johnny’s current sweet corn lineup, 'Inspiration' is the clearest fit for the region: it is well adapted to the South, with tall plants, excellent seedling vigor, big ears, and a broad disease-resistance package. 'Natural Sweet' is a good main-season organic option where common rust pressure is a concern. Also worth considering is our exclusive Organic 1r treated seed. 1r is a humic acid-based treatment that promotes overall nutrient uptake, strong root growth, and reduced stress leasing to accelerated vigor. 1r treated varieties have exhibited stunning results in our trials over untreated versions of like varieties under the same conditions. 'Quick Start', 'Temptress', 'Essence', 'Montauk', 'Superb MXR', 'Eden RMN', and 'Vision MXR' are also worth considering where their maturity window and disease package match local pressure.

Cover Crops

Cover crops well suited for growers in the Southeast have good heat and humidity tolerance, demonstrate rapid establishment in warm soils, can outcompete intense weed pressure, perform well under high rainfall conditions, and are well-adapted to mild winters. Weather variability can be common in the Southeast; therefore we also select cover crop varieties for drought and flood tolerance. Disease and pest pressures are not generally a major issue, but we look for reduced susceptibility to foliar diseases under high humidity, resistance to common soilborne pathogens, and low attractiveness to pests that overwinter on cover crops. Additional factors to consider are suitability for spring and fall plantings and ease of termination in a climate where winter kill is not a good termination option.

Cucumbers

Many field growers in the Southeast have issues with downy mildew, a common and often devastating disease, especially for those growing organically. Look for cucumber varieties with downy mildew resistance to help improve the longevity of your crop if the disease arrives.

Lettuce

Lettuce varieties well-suited to the Southeast will have good heat tolerance and a strong disease package. We look for slow-bolting varieties that demonstrate rapid growth, tipburn resistance, and a heavy leaf texture. Batavia types can be a reliable summer option in many Southeast locations. Mini lettuce can be a good choice because the shorter growing cycle creates a better chance of a successful harvest, and many of the mini varieties that we carry have strong bolt and tipburn tolerance. For a romaine, we have found that ‘Blue Rock’ and ‘Sunland’ are good summer romaine options.

For Southeast growers producing lettuce over the winter growing cycle, high vigor is critical. ‘Coastal Star’ has consistently proven itself as a standout variety for winter cycle romaine production in the Southeast.

Leafy Greens

Because heat stress can trigger premature bolting, slowness to bolt is a key trait to consider. Additionally, a heavier leaf texture can be desirable, as it means better product quality in heat. Consider the following types of leafy greens for production during high heat:

Onions

Onions form bulbs in response to daylength. Although temperature and soil fertility also influence onion growth, it is light that acts as the primary driver of bulb initiation. Southeast growers should choose short-day or intermediate-day onions, depending upon their location. Learn more about selecting onion varieties in our article Onion Bulb Formation, Daylength & Latitude.

Peas

In peas, we look for heat tolerance during flowering and pod set, and we screen for varieties that are tolerant to blanking (failure of a seed to set, leaving a blank space in the pod) in hot weather. We also look for early maturity that enables the plant to produce a harvestable crop even with short spring and fall windows. Additionally, it is important that the variety can produce full, quality pods under rapid growth conditions and fluctuating temperatures. Determinate or semi-determinate habits are helpful for a uniform harvest. Varieties that can be trellised are preferable for reducing disease pressure. Disease resistances to look for include powdery mildew, downy mildew, Fusarium, and root rots.

Peppers

Disease resistance is an important consideration when selecting pepper varieties for the Southeast. We consider bacterial leaf spot (BLS 1-10) resistance essential. Additionally, tomato spotted wilt virus (TSWV) resistance is important in some areas.

Plant habit is another consideration. We select for good leaf cover to prevent sunscald on fruit. We also look for a sturdy, upright plant habit to avoid lodging in un-trellised plants.

Summer Squash and Zucchini

Many growers in the Southeast have issues with powdery mildew and a number of different common mosaic and ringspot viruses. Look for varieties with resistance to help improve the longevity of your crop if these diseases arrive.

Tomatoes

Much of our tomato assortment will work well for growers in the Southeast generally, but for those finding themselves dealing with some of the unique challenges of southern growing, consider varieties with exceptional heat tolerance and a broad disease resistance package to help protect the plants against the various wilts, blights, nematodes, and viruses that are all common in the Southeast.

Winter Squash

Winter squash is another crop that suffers from many pests and diseases in the Southeast, such as powdery and downy mildew, squash vine borer, and squash bug, among others. While there is only so much that can be done to control damage by insects, the solid vines of squash in the Moschata species are resistant to vine borer compared to the hollow stems of those in the Pepo or Maxima species, and tend to offer some natural resistance to powdery mildew as well. Interspecific crosses like 'Tetsukabuto' (which is a hybrid of Maxima and Moschata) also have solid vines and more resilient plants generally.

Cabbage

Cabbage tends to perform much better than standard broccoli and cauliflower in warm weather, and is thus well-suited for the SE. These varieties are good choices:

  • 'Tendersweet': excellent heat tolerance as it was bred under hot and humid conditions. Outstanding for fresh and cooked dishes.
  • 'Caraflex': Excellent heat tolerance and excellent flavor and is particularly nice for slaws.
  • 'Tiara' & 'Fiaro': Excellent, crisp and sweet leaves that are particularly well-suited for summer salads as a lettuce replacement. Also good for slaws.

Chinese cabbage is mostly bred in Asia, under hot and humid condition, making it an excellent choice for hot, humid weather.

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