Summertime Lettuce Info: Growing Summertime Lettuce Plants


By: Mary Ellen Ellis

Iceberg lettuce may be considered passé by many, but thosepeople have probably never enjoyed this crisp, juicy lettuce fresh from thegarden. For a tasty iceberg with great texture that resists bolting in the summer and thatprovides consistent, quality heads, you need to try growing Summertime lettuce.

Summertime Lettuce Information

Iceberg lettuce is most often associated with sorry-lookingheads in the grocery store, boring salads, and bland flavor. In reality, whenyou grow your own iceberg in the garden what you get is crisp, fresh, mild butdelicious heads of lettuce. For salads, wraps, and sandwiches, it’s hard tobeat a quality head of iceberg lettuce.

In the iceberg family, there are many varieties from whichto choose. One of the best is Summertime. This variety was developed at OregonState University and has several good qualities:

  • It resists bolting in the summer heat and can be grown in warmer climates than other lettuces.
  • Summertime lettuce plants resist discoloration on the ribs and tipburn.
  • The heads are of very high quality.
  • The flavor is mild and sweet, superior to other varieties, and the texture is pleasantly crisp.

How to Grow Summertime Lettuce

Even though Summertime lettuce is better in heat than othervarieties, lettuce always prefers the cooler parts of the growing season. Growthis variety in spring and fall, starting seeds indoors or directly in thegarden depending on temperatures. The time from seed to maturity is 60 to 70days.

If you sow directly in the garden, thin the seedlings to 8 to 12inches (20 to 30 cm.) apart. Transplants begun indoors should be placed at thissame spacing outdoors. The soil in your vegetable garden should be rich, so addcompost if needed. It should also drain well. For best results, make sure thelettuce gets ample sun and water.

Summertime lettuce care is simple,and with the right conditions you’ll end up with tasty, pretty heads of iceberglettuce. You can harvest the leaves as they grow, one or two at a time. You canalso harvest the entire head once itis mature and ready to be picked.

Use your lettuce immediately for the best taste and texturebut at least within a few days.

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Planting Guide - Lettuce Seeds

Buttery soft or crisp with a crunch, homegrown lettuce is one of our garden’s delicacies. From early spring straight into summertime, lettuce grows fast and flavorful. This is a fun crop to grow as you can harvest the lettuce leaves at really any stage from small, tender greens to larger more mature leaves.

Planting Lettuce in Your Garden

Plant out lettuce throughout the spring and summer to ensure a continuous supply of salad. You can grow your own young plants from seed, taking advantage of all the wonderful varieties we have to offer. Lettuce makes an ideal quick crop to grow between other vegetables before they mature, or even at the front of flowerbeds and in pots.

When & How to Grow Lettuce

Lettuce seeds are small, and can be a challenge to sow individually. If you would like the “Mr. Macgregor’s Garden” look of perfectly spaced lettuce heads dotting each row, then consider starting your lettuce seeds in starter pots where you can easily thin out extra seedlings by snipping them off with scissors. Later, you can plant these starts at their correct spacing. If you would like to directly sow into your garden, keep in mind that lettuce doesn’t mind being overcrowded! Sprinkle in your seeds, and do your best to space them out. Mixing you seeds with a bit of sand will help you distribute them thinly rather than in clumps.

Lettuce is a cool-season crop that does best in a sunny location in cooler temperatures, roughly 60-65F. Wait until your ground thaws and is workable before sowing lettuce seeds, but you can begin 2 to 4 weeks before the last expected frost. Unlike other veggies, lettuce seedlings can tolerate a light frost.

Growing Guide for Lettuce Seeds

Lettuce grows in average soil. Dig about 4” deep, work in some compost and organic matter and plant your lettuce by sprinkling it in and covering with a layer of soil. Rule of thumb is that seeds should be planted to a depth of three times their diameter. For lettuce, that means approximately 1/8” deep. Expect to see sprouts in a week to 10 days.

Because the seeds are so small, the best you can do is sprinkle the seeds onto the soil, and then as the seedlings emerge, you can then begin to thin them out. Lettuce roots are small and shallow, so take care as you pull out the seedlings, or better yet, use a pair of scissors or clippers to cut at soil level. The advantage of cutting the seedlings at soil level diminishes the amount of dirt and grit you’ll have to wash off the young seedlings once you bring them inside to add to that night’s dinner salad.

We recommend 4-6 inches between butter head varieties, 10-14 inches between loose-leaf cultivars and 12-16 inches between romaine and crisp head varieties.

Keep your lettuce well watered by not soggy. If your planting area gets full sun all day long, you may want to protect this crop with some afternoon shade.

Home-grown lettuce is so wonderful, you will want to plant in succession to ensure that you have a constant harvest, so be sure to seed every 2-3 weeks. This way you won’t be without fresh lettuce during the springtime.

A small root structure and few pests makes lettuce a great companion plant in the garden. Mints, including hyssop, sage, and various balms repel slugs, a bane of lettuce. Broccoli when intercropped with lettuce was shown to be more profitable than either crop alone. Where carrots need room to grow their long roots, lettuce needs very little, and so are good companions to plant together. Growing radishes with lettuce in the summer helps to make the red vegetable tenderer. A bed containing radishes, different varieties of leaf lettuce and carrots would do well.

When and How To Harvest Lettuce

Loose head varieties called butter head or Boston include Buttercrunch, Bibb, Tom Thumb, White Boston, and Little Gem these will mature in 60-75 days. Crisp head varieties which form cabbage-like heads include Iceberg and will mature in about 75 days. Loose-leaf varieties which are suited for cut-and-come again harvests include Oakleaf, Salad Bowl Red, Salad Bowl Green, Prizehead, and Cimarron which mature in 40 to 60 days. Romaine or COS varieties with long, narrow leaves and heads include Parris Island COS, Tricolor Romaine Mix which mature in 75 or more days.

Harvest your lettuce in the morning when it is the crispest. Loose-leaf varieties can be harvested by trimming outside leaves, moving from outside in. Heading types should be just firm at harvest you can use a knife to cut heads below the lowest leaves, leaving the roots covered in soil behind.

Preparing for Next Season

Lettuce is not a heavy feeder and therefore leaves the spring soil ready for you to plant your summer veggies.


Summer Lettuce…. To grow or not to grow?

Lettuce (Lactuca sativa) is not usually a vegetable we think of growing in the middle of summer in central Virginia. It is typically thought of as a cool season crop, sensitive to high temperatures and dry soils. Lettuce tends to bolt in response to the stress of high temperatures and the leaves become bitter and tough as the plant puts its growth into flowering. However, you too can grow fresh lettuce during the summer by choosing the correct varieties, paying attention to the planting location, using shade or seasonal covering, and watering sufficiently. The following techniques will hopefully convince you to meet the heat challenge.

Soil Requirements

Lettuce will grow in a wide range of soils, but prefers a slightly acidic, loamy soil, pH of 6.0-6.5, that has been amended with organic matter. Lettuce is an excellent choice for growing in raised beds or in containers.

Seed Facts and Planting

The optimum soil temperature for germination is 60-80 degrees F. According to Clemson University research, lettuce seeds will not germinate if the soil temperature is above 95 degrees F. Lettuce is easily grown by direct seeding but if your soil temperature is over 90 degrees F, you may want to consider one of two methods: 1) precool the soil by watering and then cover the area with a board for a few days, or 2) germinate seeds indoors in a flat away from the heat and then transplant the seedlings outdoors. Either way, be sure to plant seeds no deeper that 1/8-1/4″ since many types of lettuce need light to germinate. Or, just “dust” the seeds with fine soil or compost, and then tamp down with a rake end so that the seeds make good soil contact. Keep the seedbed moist and thin the seedlings as necessary.

Choose a planting site that provides shade because too much sun is a problem during the heat of summer. Here are some techniques to try:

  • Plant in a shady area of your garden, or on the north or east side of tall plantings such as corn or caged tomatoes.
  • Take a low, hooped structure made of wire or PVC plastic hoops and place over rebar that you’ve driven into the ground. Top with a shade cloth. Cloths can be ordered from landscape suppliers who can provide different-sized cloths to fit your area. The cloths come with grommets and so can be tied down. These cloths should last for years.
  • Repurpose lightweight bed sheets as shade cloth
  • Use lightweight row covers to provide some shade I personally think you need more shade than this alone.
  • Plant lettuce in containers that you can easily move into the shade.

Selecting Varieties

Lettuce is a fast-growing crop with varieties typically maturing within 30-60 days. Sowing small amounts every 7-14 days is the recommended summer planting schedule that will provide a continuous harvest. This is also called succession planting. Selecting varieties with heat-tolerance and slow-bolting is one of the keys to success.

In general, there are four major categories of lettuce:

  • Heading or Crisphead,
  • Cos or Romaine,
  • Butterhead,
  • Loose-leaf,

Heading or crisphead types are in general adapted to northern conditions and require the most care. They are very heat-sensitive and would not be my choice for summer plantings. If you insist, VA Tech lists (VCE Publication 426-480) ‘Summer-Time’ as a heat-tolerant, heading lettuce.

Cos or Romaine lettuce has long, narrow leaves with an upright growth habit forming loose, elongated heads, firmer than loose-leaf lettuces, with a crispy, center rib. Parris Island cos (29-days), and Jericho (60-days) are considered two good heat-tolerant choices in this category.

Butterhead lettuce is a soft, tender, and loose-heading type that is divided into two subgroups: Boston and bibb. Bibb lettuces are smaller and darker green than the Boston type. All have a delicate, sweet, buttery flavor. Bibb lettuce will develop bitterness if temperatures are above 95 degrees F. Three good choices are: Buttercrunch (55-days), a small, fast-maturing, dark green bibb lettuce Tom Thumb, (35-50-days) an easy, fast-growing miniature variety of butterhead and Red Cross (48d), a heat- tolerant, red butterhead.

Loose-leaf lettuce, with either green or reddish leaves, is the most commonly grown lettuce. Leaves may be smooth, round, wrinkled, serrated or curled. The Summercrisp/Batavia lettuces are heat-tolerant plants that initially are open like loose-leaf, but then mature to a more compact bunch or head. Good choices in this category: Muir (50-days) is extremely heat-tolerant Nevada (48-days) has great flavor and stays mild Sierra (45-days) is a cut-and-come-again type with tall, open heads, thick, bright green-with-red-tinged leaves, and a sweet and nutty flavor Simpson Elite (48 days) is a loose-leaf type that is also a great summer choice similar to Black Seeded Simpson but is slower-bolting and more heat-tolerant.

Butterhead Lettuce Loose-leaf Lettuce

Care/Cultural Practices

Fertilizing: Incorporate compost and lots of organic matter into the soil prior to planting. In general, the recommendation is to use 5-10-10 at 3 pounds per 100 square feet before planting. Although lettuce has low fertility needs, it does need some nitrogen for good green leaf growth. Use a balanced starter fertilizer or compost initially, and then side-dress with compost tea or fertilizer at least once during the growing season. Of course, the amount of fertilizer depends on your soil type, with sandy soils needing the most.

Watering: The most critical period for moisture is during germination and plant establishment. Water frequently during the first 2 weeks to keep the seedbed moist but not waterlogged. A light sprinkling of leaf compost, mulch, or straw will help to conserve moisture. Continue to water lettuce once established every 4-5 days to keep the plants healthy and producing. Clemson Extension recommends watering sufficiently enough to moisten the soil to a depth of 4-6 inches. Lettuce grown in containers or raised beds will need to be watered more frequently. Over-watering in clay soils can lead to disease issues, so be careful. Water early in the day so that foliage has time to dry before dark.

Weeding: Keep your bed weed-free, which will avoid water competition and help manage insects. Lettuce is shallow-rooted so be careful to prevent root injury. Tight plant spacing will help plants to quickly shade the soil and help suppress weeds.

Insects and Diseases: The most common pests are aphids, flea beetles, slugs, cutworms and leafhoppers.

The most common diseases include dampening-off, Bottom rot disease, and aster-yellows, which is spread by leafhoppers. Both insects and diseases tend to be controlled by using cultural garden practices. You may consider using insecticidal soaps or horticultural oils, but be sure to read the labels.

In summary, you can grow lettuce in the summertime heat by:

  • Choosing varieties that are heat-tolerant and slow-bolting. My 3 favorites are easy to remember: Muir, Sierra, and Nevada.

  • Choose a planting site that provides shade.
  • Don’t skimp on water.
  • Make successive plantings to replace spent plants.
  • Use sound cultural practices: inspect plants for insects and diseases, hand pick and destroy destructive insects, and remove diseased leaves or plants.
  • Harvest regularly and enjoy!

Thanks for stopping by The Garden Shed. We hope you visit us again next month.

“Home Garden Lettuce”, University of Georgia Extension, Publication C1018, http://extension.uga.edu/publications/detail.cfm?number=C1018

“Vegetables Recommended for Virginia”, Virginia Cooperative Extension, Publication 426-480, https://www.pubs.ext.vt.edu/426/426-480/426-480.html

The Timber Press Guide to Vegetable Gardening in the Southeast (Regional Vegetable Gardening Series) by Ira Wallace, 2013

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