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How to Grow Lettuce from Seed
Growing lettuce from seed in your garden is rewarding and super easy! With our pro tips and tricks, you will understand how to grow lettuce from seed, when to harvest lettuce at the correct stage, and how to get the most out of your lettuce patch!
When to Plant Lettuce Seed
Lettuce is a cool-season crop which means it likes to grow in cooler weather with ample moisture. Lettuce seed can go into thermal dormancy when the temperatures are too warm — seeds will be slow to sprout or will not sprout at all if the temperatures are too high. The ideal temperature range for germinating lettuce seed is 60–70 degrees. Luckily for many in Southern California, these are common temperatures year-round! In coastal zones, lettuce can be grown year-round because of the mild weather. In other areas of the United States, you can grow lettuce during the cool months of the fall, spring, and even into early summer if you give it a bit of shade or protect it with shade cloth. That’s one advantage of growing lettuce in a pot; you can move it!
Lettuce Seed Varieties
There are hundreds, if not thousands of lettuce varieties that you can find when shopping for lettuce seeds. That is one of the best advantages of growing lettuce from seed. You have many more lettuce varieties available to you than if you buy transplants. It is also more cost-effective to plant lettuce from seed.
Lettuce can be of varying colors, textures, and flavors. When shopping for lettuce seeds, remember that lettuce is generally organized in several categories. Crisphead or iceberg lettuces are mild in taste and have a great crunch! Here in Zones 9 and 10, you can grow crisphead or iceberg lettuces well into the warmer months since they can handle more heat than delicate lettuce varieties.
Our Great Lakes lettuce variety is super resilient to pests and grows great even in our warm winter and spring weather. Romaine lettuces are common in the grocery store, but nothing beats a fresh romaine head straight from the garden! Our Jericho variety of romaine lettuce was bred in Israel and can withstand high spring temperatures. Great for southern growers!
Unlike iceberg or romaine, loose-leaf lettuce varieties are grown specifically to harvest individual leaves instead of a whole head. Typically, loose-leaf lettuce is grown to make fresh lettuce mixes. Varieties like our Mesclun mix are pre-mixed seed ready for you to plant and grow your own salad mix. More incredibly tasty varieties are Bibb or butter lettuces. They are mild, buttery, and super succulent. Our Buttercrunch and Marvel of Four Seasons are two very buttery varieties! These lettuce categories can be broken down further into subclasses. But for the beginning gardener, the most important thing to understand is whether the variety you are growing is meant to be a head lettuce or leaf lettuce. That will determine how you harvest it!
Growing Lettuce from Seed
Growing lettuce from seed is easy, quick, and economical. Seeds can be started indoors in late spring if you get frost in your area. You can start them outside if you do not get frost and the temperatures are between 60–80 degrees. We recommend that you start seeds in a good seed starting mix soil. Seed starting mix is formulated to help seeds easily sprout through the soil and stay moist during germination. Lettuce seeds should sprout in 3–10+ days.
Keys to helping your seeds sprout quickly are to make sure you do not plant them too deeply and that you cover them about ¼” with finely sifted soil. By sifting your soil, you can guarantee that no large pieces of soil, mulch, or other particles are covering your seeds, making it hard for them to sprout. When you are planting your seeds in the ground or in trays or pots, the soil should remain moist continuously until the seedlings have sprouted, which should be between 3–10 days. If your seedlings have not sprouted, consult our troubleshooting guide to determine what you may have done wrong.
Growing Lettuce Plants
Once your lettuce seed has sprouted, you need to get it growing! The first leaves you see on your sprouts are called cotyledons. These are the leaves stored inside the seeds and are part of the plant’s embryo. The leaves that follow are called first true leaves. They are the signal to you that you need to fertilize. The best fertilizer for your baby plants is a liquid fertilizer with an even number of nitrogen, phosphorus, and potassium. For example, a good product is a liquid fish emulsion with 2–2–2. Harsh chemical fertilizers can burn your plants, so use a natural or organic fertilizer if possible.
Lettuce Companion Plants
Lettuce is a leafy green that can be susceptible to insects who love their tasty leaves. You can plant companion flowers to bring beneficial insects to the garden to help with the issue. Flowers like marigolds, nasturtiums, gaillardia, borage, alyssum, and scabiosa all do particularly well around lettuce plants. They also look beautiful! You can even add the blooms of nasturtiums and borage to your salad!
Pro Tips for Southern California Growers
For those in Zones 9 and 10, starting lettuce seed in warmer months can be challenging. If you are trying to start lettuce during the warmest months of August through October, use shade cloth to protect your baby seedlings until they are well adjusted to the heat or until the days cool off. Layers of mulch and compost will help keep the soil cooler while also keeping moisture in. If you are a new gardener, it may be best to stick to starting your lettuce from seed in the cooler months of late fall and winter.
Planting Lettuce Seed in Containers or In-ground
Lettuce is an easy plant for growing both in the ground and in containers. Lettuce generally stays tidy and will not sprawl like other plants, making it great for planting in containers or raised beds. One advantage of growing lettuce in a container, such as a transportable pot, is moving it to shadier areas during hot months. If your growing area is really small, you may want to grow loose leaf lettuce because you can get several harvests from one container or growing site. Growing lettuce in the ground is very easy too! You can plant them in raised beds or directly in the ground. Make sure you amend with compost to help the soil stay cool and moist, particularly in warm climates.
Depending on the variety of lettuce you are growing, you will use the cut and come again method for loose-leaf lettuces or harvest the whole head. If you are using the cut and come again method, you will simply give your lettuce a short haircut! Take the lettuce in one hand, hold it together, and trim it with scissors. The plant will regrow happily, and you will be slowing down its desire to go to flower; going to flower makes the plant taste bitter.
If you are growing iceberg or head lettuce, you will want to cut the whole head. Take a sharp knife and cut at the base of the plant at the soil level to harvest your head. The best indicator of a lettuce head being ready is to mark your calendar with the date of maturity given on the seed pack. That way, you know for sure it’s ready to harvest. If you do not know the days to maturity for your variety, you can simply ask yourself if the lettuce looks big enough to harvest. If so, go for it! Do not let lettuce get too big as it will get bitter. The best-tasting lettuce is harvested at its peak freshness.