Lettuce

Lettuce for Every Grower • How to Choose and Grow the Best

How to Choose & Grow the Best Lettuce

Lettuce for Every Grower

Lettuce is a crop that offers something for every grower. Versatile, universally popular, and always in demand, it's a high-value crop at market and a staple in the home garden. Relatively easy and fast-growing, lettuce is also adaptable to a range of conditions, seasons, and growing methods.

With its great diversity — over a thousand different varieties of lettuce exist nowadays — choosing which ones to grow can be a job in itself if you're not sure what you're looking for.

Johnny's runs an extensive lettuce trialing program to be sure the varieties we offer each year are the best available. Here is our guide to the basic types of lettuces, so you can decide which varieties are right for you, plus some of the fundamentals of lettuce growing success.

Basics for Every Lettuce Grower • Turnaround Time, Temperature, End-Product

Fishbowl Farm, Bowdoinham, Maine
3 Lettuce Basics: 1) Quick turnaround time. 2) Moderate temperatures. 3) Diverse cultural methods & end-products.
Above: Red and green lollo head lettuces and baby leaf mixes grown at Fishbowl Farm, in Bowdoinham, Maine.

Whether you are choosing varieties for the home garden or developing a full lettuce planting program for market sales, there are a few general considerations to take into account.

  • Turnaround time. Lettuce (especially baby leaf) has a relatively short time to maturity. This means that succession planting — sowing at intervals — is a necessity if you want to have a continuous supply throughout the growing season. For more specifics, see our Succession Planting Interval Chart for Vegetables.
  • Temperature. Lettuce prefers moderate temperatures and is best suited as a spring or fall crop; it tends to become bitter and bolt (flower and go to seed) in the heat. Some varieties are more tolerant of temperature extremes than others, so it is fundamental to choose the right varieties for each season — heat-tolerant varieties for summer and cold-tolerant varieties for fall.
  • End-product. Lettuce production can focus on one or more end-products, from full-head and mini-head to baby leaf assortments, and some varieties are better for one or another end-use. It's important to understand your market demand as you choose varieties and develop your planting program.

Choosing Lettuce Types • Baby Leaf, Mini Head, Full Head, One-Cut, Cut-&-Come-Again

The many different categories of lettuces are roughly classified by their leaf shape, configuration, and how much of a head they form. But even though there are lots of types and varieties, they are all the same species and open-pollinated. That means they can all be crossed, which results in blending between types, and you will sometimes find varieties don't fit perfectly into only one category. The aptly named 'Fusion' is a classic example in our assortment.

Lettuces are roughly classified by leaf shape, configuration, and how much of a head they form.
Lettuces are roughly classified by leaf shape, configuration, and how much of a head they form.
Lettuces readily cross with one another, however, and the result is that some lettuces possess features of two or more distinct categories!

HEAD LETTUCE: FULL-SIZE HEADS & MINI HEADS

Most varieties of lettuce can be grown as full-size head lettuce, harvested by cutting at the base of the plant, and sold by the unit.

Mini-head lettuces are either standard head lettuce varieties that are planted at close spacing and harvested early, before they are fully mature, or, they are varieties that mature at a naturally small, compact size. In either case, the result is a single-serving sized head lettuce.

For market growers, mini-head lettuce can be more profitable than full-size heads; to learn more about the cost/benefit ratio of the two, read Growing Mini versus Full-Size Head Lettuce: A Look at Differences & the ROI.

Primary head lettuce types include:

  • Butterhead. Generally grown to full-size heads, butterhead lettuce has a beautiful ruffled appearance, with a blanched heart and a delicate, sweet, and buttery flavor. "Boston" lettuce is a subtype of butterhead, with varieties that have a lighter green color, softer and smooth textured leaves, and nice big heads. Other butterheads can be darker shades of green, a little more compact, and have blistered/savoy leaves, or can be red butterheads.
  • Bibb. Similar in appearance, texture, and flavor to butterhead, but smaller, bibb lettuces are generally grown for mini-heads.
  • Crunchleaf. A range of newer lettuces with unique leaf and head forms, combining or demonstrating overlapping traits of icebergs, romaines, and other traditional lettuces — all with that popular high-crunch "tooth feel."
  • Iceberg. Iceberg, also known as crisphead, forms a dense head resembling a cabbage. It offers a fresh, crunchy texture and sweet, mild flavor.
  • Lollo. Lollo lettuces form loose heads with very frilly leaves that are often used for garnish. Lollo can also be used for baby-leaf production. The leaves are characteristically wide, and can be used for wraps in addition to garnishes.
  • Oakleaf. These varieties form attractive, relatively dense, rosette-like heads of curly, crisp leaves that are characteristically deeply lobed and similar in shape to those of oak trees. Primarily grown for baby-leaf production; some varieties perform well when grown to full-head size.
 'Auvona' is an open-heart romaine that differs from traditional romaines in leaf shape, dimension, and ease of preparation.
Lettuce is an open-pollinated crop with many forms which by nature readily combine and overlap.
Above is an "open-heart" romaine that differs from traditional romaines in leaf shape, dimension, and form.
  • Romaine (Cos). Romaine is best known for its compact hearts of long, broad leaves. The outer leaves can also be used as wraps. The flavor is sweet, and the texture is crisp. Some romaines have a more open plant habit than those that form the classic tall, blanched hearts. The open forms do eventually blanch but not as much, and cannot be harvested strictly as hearts. Romaine lettuce does best when provided higher fertility than loose-leaf types require.
  • Summer Crisp / Batavia. As the name suggests, summer crisp is the ideal choice for summer lettuce. It is relatively tolerant of hot weather and can be grown to either baby-leaf or full-head size. The full heads are heavy and compact. Similarly to romaine, summer crisp grows best with slightly more fertility than loose-leaf types. Summer crisp is also sometimes called French crisp or Batavia.

BABY LEAF LETTUCE & CUT-&-COME AGAIN (CCA)

Varieties best for baby-leaf production have vigorous, uniform growth, thick leaf textures, and upright growth habit.
Varieties that are best for baby-leaf production have: 1) vigorous, uniform growth; 2) thick leaf textures; 3) upright growth habit.

Essentially any lettuce variety can be grown as a "baby leaf" by planting the seed at high density and harvesting the leaves very young. The varieties we identify for baby-leaf production, however, are particularly well-suited because of their vigorous, uniform growth and thick leaf textures, as well as for their upright growth habit, making them easier to harvest and cleaner to harvest in the field. These varieties do not produce particularly good full heads if grown to maturity; the heads tend to be loose and lightweight.

Baby leaf lettuce is usually harvested at about 3–4 weeks from seeding. Some baby leaf varieties take up to 5–6 weeks to mature, though, even when spring-planted, and definitely when fall-planted. To harvest, cut baby leaf lettuce 1–2" above the ground, using a knife, shears, or a mechanical harvester.

All the varieties identified as suitable for baby leaf production can be used for cut-and-come-again (CCA) growing systems, meaning they will regrow after the first harvest, provided the basal growing point of the plant is not damaged when the leaf stems are cut. Some varieties are a little better than others for CCA harvesting, because they regrow faster and more uniformly, hold their flavor, and hold their size. The quality and quantity of the second cut are typically lower than the first.

You will want to seed weekly to ensure a steady supply of baby leaf lettuce throughout the season.

Baby leaf varieties primarily include romaine, summer crisp, and oakleaf types. Johnny's also carries several lettuce mixes, comprised of multiple varieties that mature at similar rates. These mixes create an appealing assortment of color, texture, and loft. Some growers add herbs, edible flowers, baby brassica greens, baby specialty greens, sprouts or shoots to baby-leaf lettuces to create signature salad mixes; for more information, view our Baby Leaf Greens & Lettuce Production Guide.

Salanova, the industry standard one-cut type, excels under a wide range of conditions and cultural settings.
Salanova, the industry standard one-cut type, excels under a wide range of conditions and cultural settings.

ONE-CUT LETTUCE

One-cut is an industry term for a type of full-size head lettuce, some of which are best grown for a single harvest and others in a cut-and-come-again fashion. These are recently developed lettuces that go by several trade names, including Eazyleaf, Multileaf, Multi-Cut, and our hands-down favorite, Salanova®. In our yearly trials, however, we have identified several additional, recently developed one-cut types for production on their own or to pair with Salanova.

  • Salanova is the industry standard one-cut type for baby-leaf production, and it excels in a variety of cultural settings, from the field to winter tunnels or as a hydroponic lettuce. It is grown to full-head size, but when cut at the plant base, the individual leaves separate, creating a final product similar to baby leaf lettuce. It is more than 40% higher yielding, has better flavor and texture, and double the shelf life, compared to traditional baby leaf lettuce. For more information on the different core structures, colors, and leaf types, see our Salanova brochure. For cultural specifics, refer to our Salanova Lettuce Production Guide.
  • 'Rubygo' and 'Verigo' are square-leaf types that produce a high count of uniform, attractively-edged, strong but flexible leaves at maturity. With a thick, juicy texture and great flavor, these make excellent sandwich or burger leaves. Or, they can be simply cut up for a salad mix addition. They are great for pairing with one another, or with any of the cored-type Salanova series for mixed whole-head sales. Rubygo has a true mini size frame, whereas Verigo will reach a slightly larger size at maturity.
  • 'Frisygo' is an endive-leaf type lettuce — "frisée without the bitterness" — unique and delicious. Its deeply incised, uniform baby leaflets combine an appealing iceberg texture with complex flavor. The heads' compact, upright growth habit allows for equal benefit as whole-head or saladmix end uses. And they are just as easy to multiharvest in the field as Salanova incised types, but also retain their whole-head shape through the wash/pack line.

To learn more about these options and how we select from our one-cut variety trials, see our One-Cut Lettuce Varieties Insert.

Selecting Lettuce Varieties by Seasonal Slot & Cultural Method

Summer lettuce trials at our research farm in Albion, Maine
Summer lettuce trials at our research farm in Albion, Maine

Once you have narrowed down the types of lettuce you want to grow, you can select specific varieties. You will most likely want to select several varieties for each of your intended production seasons — spring, summer, fall, and winter — depending on your latitude, microclimate, and cultural methods.

Summer lettuces are varieties that have been bred and selected for resistance to bolting and tip burn. Compared to other varieties, they are less likely to become bitter and go to seed during the heat of summer. Even heat-tolerant varieties have upper limits of temperatures they can withstand. At lower latitudes and in geographic pockets of intense summer heat such as the South and Southwest US, most growers avoid outdoor lettuce production during the warmest part of the season.

Winter lettuce trials at our research farm in Albion, Maine
Winter lettuce trials at our research farm in Albion, Maine

Conversely, some varieties are particularly frost-tolerant and good choices for a fall harvest or tunnel production. Fall/winter/cold-tolerant varieties are also selected for bottom rot resistance (soils stay wetter in cooler seasons) and ability to hold their shape and color in lower-light conditions.

You can use the filters on our lettuce product pages on our website to select for heat tolerance and cold tolerance, winter harvesting, overwintering, greenhouse production, and hydroponic production.

For an example head lettuce succession plan, see our full-size head lettuce planting program. This planting program is designed to guide you in selecting and timing the sowing of early, mid, and late-season varieties for a continuous harvest of full-size head lettuce.

LETTUCE FOR HYDROPONICS

Lettuce varieties that excel in hydroponic growing environments typically have a compact and upright growth habit to maximize greenhouse space; resistance to tip burn, which can be a problem for rapidly growing greens; resistance to bolting; and resistance to diseases, such as downy mildew, that are common in indoor growing environments.

Johnny's has lettuce varieties recommended specifically for hydroponics, selected on the basis of results of trials with independent hydroponic growers, in combination with our own variety knowledge and the information we receive from our suppliers.

See our Digital Hydroponic Lettuce Catalog for more about how we choose these varieties and an overview of our types.

Types of Lettuce Seed • Organic, Conventional, Pelleted

Johnny's offers different types of lettuce seed to accommodate the year-round needs and preferences of our customers. For lettuce, we offer over a hundred different variants, in the following seed types. All our seed is non-GMO.

Pelleting lettuce seeds makes them easier to handle and sow, and in some cases, assists germination.
Because lettuce seed is very small, fusiform (spindle-shaped), and ribbed, it is not easily handled in its raw form. Handling and sowing accuracy — whether by hand or by mechanical planter — are greatly facilitated by the use of pelleted seed.
  • Certified-Organic Lettuce Seed. Seed that has been harvested from plants grown strictly without the use of inputs disallowed by the USDA National Organic Program (NOP), and packed in a certified-organic product handling facility.
  • Certified-Organic Lettuce Seeds with NOP-Compliant Pelleting. Pelleted seeds are coated with an inert substance to improve visibility, handling, and suitability for use in precision seeders. In this case, the substance is composed of materials approved for use in certified-organic production by the USDA NOP.
  • Conventional Lettuce Seed. Produced under conventional growing and handling conditions.
  • Conventional Lettuce Seed with NOP-Compliant Pelleting.
  • Conventional Lettuce Seed with Conventional Pelleting.

See our Quick Lettuce Reference Chart for a comprehensive list of all the lettuce varieties we carry, broken out by type; color; availability in organic, conventional seed, or pelleted seed type; and each variety's suitability for baby leaf, mini, or full-size head production. Use the filters on our lettuce product pages to return lettuce varieties that have the particular features you seek.

PELLETED LETTUCE SEED

Because lettuce seed is small, we offer many of our varieties in pelleted versions. Pelleting can help make it easier to handle the seeds and sow the seeds accurately, either by hand or with a mechanical planter. Note, however, that the pelleting process reduces the shelf life of the seed; pelleted seed should be kept cool and dry and used within one year of purchase.

An additional benefit of using pelleted lettuce seeds is that the pelleting process can help improve germination. Lettuce seed can enter thermal dormancy when exposed to high temperatures, meaning it will not germinate at high temperatures. Many pelleted seeds undergo a priming process that broadens the temperature range within which the seeds will germinate, overcoming some of this thermal dormancy.

Lettuce Growing Tips

Start lettuce seedlings in flats 3–4 weeks before transplanting.
For an early harvest or to make the most of bed space, start lettuce seedlings in flats 3–4 weeks before transplanting.
  • Lettuce can be direct-seeded, but for an early harvest, or to make the most use of bed space, start seedlings in flats 3–4 weeks before transplanting.
  • Seeds will germinate poorly if temperatures are too high; when starting seeds, choose a cool location and/or shade the flats during warm, sunny weather.
  • Irrigate well — lettuce prefers consistent moisture, and drought-stressed plants will be bitter. If using pelleted seed, note that adequate and consistent moisture is required to dissolve the pelleted coating and enable the seed to germinate.

For more detailed and specific instructions, refer to the Growing Information accordion on the lettuce variety's product description page.

Lettuce Harvesting & Storage Tips

Non-profit organization DC Urban Greens brings low-cost, fresh to the city's food deserts.
Baby leaf mixes are usually washed and dried thoroughly before being packaged and stored.
Non-profit organization DC Urban Greens brings low-cost, fresh produce such as this baby leaf lettuce, to the city's food deserts.
  • Harvest lettuce by hand, or with a knife or a mechanical harvester, before the plant becomes bitter and bolts.
  • Once harvested, lettuce should be cooled as soon as possible to remove field heat. Head lettuces can be hydrocooled and, except for romaine, iced, either by package icing or by bulk application to the top of a load.
  • Baby leaf mixes are usually washed and dried before being packaged into bags or clamshells. Their shelf life will be extended by drying the leaves thoroughly before packaging and storing. Store refrigerated in plastic bags or tubs.
  • Shelf life varies, but under optimal storage conditions, in the vicinity of 32°F (0°C) at 95–100% humidity, lettuce will keep for 7–21 days.