ABOUT THE PLANT
Description: Lettuces can generally be placed in one of four categories: looseleaf, butterhead, crisphead, and romaine. Iceberg is a crisphead type having large uniform crisp leaves that grow in a spherical head resembling cabbage. A mature iceberg lettuce head can grow up to one foot in diameter. Iceberg has a mellow and mild taste and a firm, crunchy texture.
Origin: Lettuces originate in the eastern Mediterranean and western Asia. Iceberg lettuce was developed from the French Crisphead lettuce, Batavia, by W. Atlee Burpee & Co. in 1894.
Usage: Iceberg lettuce is great for crunchy salads, shredded on tacos, on sandwiches, and it makes nice big wraps.
Interesting facts: Iceberg lettuce holds up well in storage. It was named Iceberg because, before refrigerated train cars, the lettuce was packed in ice. Iceberg lettuce is still the most popular but is giving way to Romaine and loose leafs.
HOW TO GROW
General requirements: Iceberg lettuce is a cool-season crop that grows well in the spring. It’s important to time the crop to mature before hot, dry weather sets in. Depending on your location, it might be best to start the plants indoors about a month before the last frost. It can also be planted as a fall crop if started indoors, but you need to time your fall crop to mature before the first fall frost date for your area. It takes about 70 days for Iceberg lettuce to reach full size. Plant indoor succession crops every week or two. Lettuce prefers loose soil rich in organic compost that is kept moist and well-drained. The plants have shallow roots and respond best to consistent, shallow watering. It grows best in full sun, though high temperatures will cause it to bolt and go to seed. It can be seeded directly into the garden, in containers, or started indoors and transplanted later. Remember, it takes about 70 days to reach full size. Because lettuce seeds need light to germinate, place seeds directly on top of the soil and cover lightly by "sprinkling" fine soil over them. Expect germination in 7-10 days.
In the garden: Sow seeds directly onto cultivated soil, at a soil temperature of at least 35 degrees F. Seeds will not germinate in soil temperatures above 75 degrees F. Seeds should germinate in 7-10 days. When 2 or 3 true leaves have appeared, thin to 12 inches apart. Or, plant 1 inch apart in rows 12 inches apart. Thin to 12 inches apart. Use the thinnings in salads. A layer of mulch will help keep plants clean and retain moisture.
In containers: Use professional potting soil for planting in containers. Iceberg lettuce needs to be about 12 inches apart whether seeding directly or transplanting. Do not allow the soil to become soggy. Use containers with drainage holes.
Transplanting: For a spring crop start indoors in trays or cells about 1 month before the last frost date. It’s important to time the crop to mature before hot, dry weather sets in. It takes about 70 days to reach full size. Before transplanting, the seedlings should be 2-3 inches tall and must be hardened off, or acclimated, to the outside environment. To harden off, place the plants outside in the sun for 2-3 hours the first day. After the first day, increase the amount of time outdoors by a couple of hours each day until your lettuce plants can finally be left out for 24 hours. The hardening-off process can take 7-10 days. Once your lettuce plants are hardened off they will be ready to transplant into your garden or outdoor container. For a fall crop, you need to time your crop to mature before the first fall frost date for your area. It is best to transplant on an overcast day or later in the day when the sun is less intense. Remember, the root system is shallow and you want to prevent transplant shock. Set plants 12 inches apart and to the same depth as they are in the tray or cell that they are coming from. Water thoroughly.
The head: Harvest the entire head of lettuce by using a sharp knife or scissors. Cut the entire head at the base of the plant. In temperate regions leave about an inch or so of the plant above the soil surface so it can regrow.
Seeds: When a head of lettuce bolts, the stem within the head elongates and branches. This flowering stem reaches 2 to 4 feet in height. Wait until the flower heads are fluffy and dry before harvesting. Hold a bag under the flowers and shake them into the bag. Do this daily until most of the mature seeds are collected. Or, cut off a stem of flower heads and shake them inside a bag. Seeds can be separated from the chaff and other debris by sifting through a metal mesh strainer. Seeds are better if collected from plants that are slower to bolt. Store them in a cool, dry place for next season's planting.
Common Names: Iceberg, head lettuce, crisphead lettuce.
Latin Name: Lactuca sativa
Growth habit: Upright, herbaceous, forming a dense head of leaves.
Life Cycle: Annual
USDА Zones: 3-12
Seeds per Ounce: 20,000