Lettuce for Every Grower - How to Choose & Grow
Lettuce is a crop that offers something for every grower: versatile, universally popular, and in steady demand, it is a high-value crop at market and a staple in the home garden. Relatively easy and fast-growing, lettuce is 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. We run an extensive lettuce trialing program to be sure the varieties we offer each year are the best available. Here are basics of the lettuce varieties that are right for you, along with some of the fundamentals of growing lettuce successfully.
Lettuce Basics • Turnaround Time, Temperature, End-Product
Whether 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.
3 Lettuce Basics: 1) Quick turnaround time. 2) Moderate temperatures. 3) Diverse cultural methods & end-products.
•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
Lettuces are roughly classified by leaf shape, configuration, and how much of a head they form. But while there are all these different categories of lettuce, it's helpful to remember that they are all the same species, which means they can be crossed, so you often find some varieties that don't fit perfectly into only one category. The aptly named 'Fusion' is a classic example in our assortment.
HEAD LETTUCE: FULL-SIZE & 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.
Mini-head lettuce can be more profitable for the grower 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: Bibb lettuce has a similar appearance, texture, and flavor to butterhead, but it is smaller, and is generally grown for mini-heads.
•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 forms 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.
•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 implies, summer crisp is the ideal choice for summer lettuce. It is relatively tolerant of hot weather and can be grown for either baby leaf or full-size heads. 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.
•Green Leaf/Red Leaf: These include varieties such as 'New Red Fire' and 'Tropicana'. They are commonly found in grocery stores, banded with the foil ties around them. Used for salad, sandwiches, or wraps.
BABY LEAF LETTUCE
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 vigorous, uniform growth, thick leaf textures, and 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, however, 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 baby leaf varieties can be used for cut-and-come-again growing systems, meaning they will regrow after the first harvest, but some are a little better than others 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 Salad Mix Production Guide.
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®.
•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 the different core structures, colors, and leaf types, see our Salanova brochure. For cultural specifics, refer to our Salanova Lettuce Production Guide.
Selecting Varieties by Seasonal Slot & Cultural Method
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.
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 recommended varieties 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.
Types of Lettuce Seed • Organic, Conventional, Pelleted
Pelleting lettuce seeds makes them easier to handle and sow, and in some cases, assists germination.
Lettuce seed is very small; pelleting helps with handling and accurate sowing, either by hand or with a mechanical planter.
PELLETED LETTUCE SEED
Because lettuce seed is small, 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 produce, including this baby leaf lettuce, 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.
taken from http://www.johnnyseeds.com/growers-library/vegetables/lettuce-how-to-choose-grow-
till next time this is Becky Litterer, Becky's Greenhouse, Dougherty Iowa