The time it takes to grow lettuce varies significantly based on its specific variety and environmental conditions. Lettuce is a fast-growing, cool-season crop, but the total duration from planting to a full harvest can range from just over a month to nearly three months.
Average Time to Harvest by Lettuce Type
The genetic makeup of the lettuce variety is the primary factor determining its growth speed and maturity time. These timelines are generally measured from the point of planting a small seedling, or transplant, into the garden.
Looseleaf lettuce, which includes varieties like Black Seeded Simpson and Salad Bowl, has the shortest maturity period, often ready for a full harvest in about 30 to 45 days. These varieties are favored because their leaves can also be picked individually in a “cut-and-come-again” method, allowing for continuous, earlier harvests of baby leaves.
Butterhead or Bibb varieties, such as Buttercrunch, take a moderate length of time to develop their characteristic loose, soft heads. These types typically reach full maturity and are ready to be harvested as a whole head between 50 and 60 days after planting. Romaine, also known as Cos lettuce, and Crisphead varieties, such as Iceberg, require the longest growth period to form a dense, upright structure. A full head of Romaine or Iceberg is usually ready for harvest after 65 to 80 days.
Starting from Seed Versus Using Transplants
The method of planting directly affects the total time until a harvestable plant is ready. Starting with a transplant, an established seedling, immediately shortens the overall waiting period. Transplants bypass the initial germination and fragile seedling stage, cutting approximately 15 to 20 days off the total time to harvest.
If a grower chooses to start with seeds, the germination period must be added to the overall timeline. Lettuce seeds typically sprout within 4 to 10 days under optimal conditions. After germination, seedlings require a few weeks to grow large enough and strong enough to be safely transplanted outdoors, a process that takes about three to four weeks total before they are ready for the garden bed.
Environmental Conditions That Change Growth Speed
Lettuce is a cool-weather crop, and its growth rate is highly dependent on maintaining a specific temperature range. The ideal temperature for rapid, healthy growth is between 60 and 70 degrees Fahrenheit. Within this range, the plant focuses its energy on producing the large, tender leaves that are desired for consumption.
When temperatures consistently rise above 75 degrees Fahrenheit, the plant’s growth pattern changes dramatically, a process known as bolting. Bolting is the plant’s natural response to stress, where it prematurely shifts from growing leaves to producing an elongated flower stalk and seeds. This transition effectively ends the harvest period because the leaves become tough and accumulate a bitter, unpalatable latex substance.
To avoid this premature end to the harvest, growers must ensure consistent access to water and sufficient light. Lettuce requires about five to six hours of sunlight per day, but providing afternoon shade in warmer weather can help keep the soil and plant cool, delaying bolting. Maintaining consistently moist soil prevents the plant from becoming water-stressed, another factor that can trigger the bolting response and slow down overall growth.