Lettuce is a cool weather crop, so it will bolt (grow tall, then produce flowers and seeds) in high temperatures. Choose a spot that receives a minimum of four to six hours of direct, full sunlight each day. What Are Pelleted Seeds? If the soil is any warmer than this, germination rates will decrease. Water temperature and effects on hydroponics What is the best water temperature for plants? This makes the leaves inedible to anyone with taste buds. Don’t Ever Plant Anything But Heirloom Seeds If you cover the plants with multiple layers, lettuce can survive down to 0 degrees Fahrenheit or -18 degrees Celsius. The ideal soil temperature for germination though, is 70 to 75 F. In cooler temperatures, germination takes longer. As with many crops, there are differences between varieties within the same species. The table below summarizes the temperature ranges for lettuce growth. A cloche is a clear plastic or glass cover used to protect plants from cold, pests, and wind. The apical meristem of young lettuce plants is near the soil surface, so plant growth is often more closely matched to soil temperature than air temperature. For example, if a hard frost comes suddenly after warm weather, then lettuce may not survive. In this article, we’ll talk about the ideal temperatures for lettuce germination and growth. If so, please share it with someone who can use the information. © Copyright 2020 Hearst Communications, Inc. Lettuce can tolerate a few days of temperatures from 80 to 85°F, provided that nights are cool. If the temperature becomes too warm or too cool for lettuce plants to grow well outside, they can be moved indoors permanently as long as they have enough light. However, lettuce loves the cool weather (80 degrees F or less) and is challenging to grow … Seed will germinate at temperatures between the minimum soil temperature and the optimum soil temperatures, but the number of days to germination will be greater. When the weather gets warmer, lettuce will start to “bolt” or go to seed. When temperatures dip below 2 degrees celsius, consider covering plants with a row cover, cloche or other apparatus. We’ll also get into ways you can protect lettuce from cold weather and how to prevent bolting in warm weather. (Plus 7 Heat Tolerant Varieties). At night, on the other hand, you need to keep the temperature at about 50 to 60 degrees Celsius. This vegetable gives higher yield when the temperature is maintained no higher than fifteen to twenty degrees Celsius. You also know how to protect lettuce from temperature extremes to extend your harvest. Growing Lettuce in Extreme Summer Heat – In a Vegepod! The ideal temperature for growth of lettuce plants is 55 to 65 degrees Fahrenheit (13 to 18 degrees Celsius). University of Illinois Extension: Lettuce, North Carolina State University: Lettuce Production, University of Arizona: Seed to Seed -- Fresh Produce Safety, How to Sprout Lettuce Seeds in Hot Weather. As an added bonus, shade cloth can protect lettuce from birds. If direct seeding, scatter the lettuce seeds lightly and evenly over a moist, but not soaking wet, soil surface. The right temperature is anywhere from 60 to 70 degrees Fahrenheit. learn more about Jericho lettuce from Johnny’s Selected Seeds. When a sudden hard frost threatens, your lettuce might be able to survive. Grow above 70 F during the day and above 60 F at night. This shade cloth from Gardener’s Supply Company can be used with hoops for support. Does your lettuce need to be protected from frost? That said, when growing lettuce hydroponically you should ensure that the day temperatures range between 20 and 23 degrees Celsius and never at any point exceeding 25 degrees Celsius. Depending on the grade of the shade cloth, it can provide up to 10 degrees of heat protection for your lettuce! Most lettuce varieties germinate well in the range of 10 to 15 degrees Celsius making them an excellent winter crop for gardeners in temperate areas. If you want the lettuce to develop fully grown heads, then leave 10 to 12 inches between the seedlings. Growing Lettuce in an AeroGarden is a fantastic way to get your children involved and use the leaves to make their salad sandwiches. Best Germination Temp: Best Night Growing Temp: Best Day Growing Temp: Geraniums: 75°F: 50-60°F: 65-75°F: Hydrangeas: Best from cuttings: 60°F: 70°F: Beets: 50-85°F: NA: 60-65°F: Carrots: 50-85°F: NA: 40-85°F: Lettuce: 65-75°F: 60-70°F: 60-70°F Enjoy! Plant when soil temperatures warm up to 35 to 40 degrees F. In general, cool season crops can be planted two weeks before the last frost date. Use a handful of pine needles around tender seedlings to help prevent wind damage and also provide support. The lettuce will still grow after it has started to bolt. There’s no ideal climate for all lettuce types, but most grow best in cool weather. (3 Things To Know), link to Are Onions Heat Tolerant? Lettuce is adapted to cool growing conditions with the optimum temperatures for growth of 60 to 65°F. The ideal temperature for growth of lettuce plants is 55 to 65 degrees Fahrenheit (13 to 18 degrees Celsius). based on information from the University of California Extension. Lettuce is a crop that grows better in a cooler environment. a hydroponic lettuce is still a growing plant with roots and leaves, an onion or potato can re-sprout and grow into a new plant under the right conditions). The ideal temperature range for lettuce seed germination is 60 to 86 degrees Fahrenheit (16 to 30 degrees Celsius). Enjoy! As the tomato plants grow, they will provide some shade for the lettuce. Tip: Harvest sooner rather than later to avoid a bitter lettuce flavor. learn more about cloches in my article here. Depending on its variety, lettuce seed can germinate when the soil temperature is 35 to 80 degrees Fahrenheit. I don't know of any plants that die just because it's 40° C. (104° F.) 10. For extra early crops, start plants inside 3 to 4 weeks before transplanting. For the best results, keep the temperature around 55° Fahrenheit (12.7° Celsius) at night and around 75° Fahrenheit (23.8° Celsius) during the day. You can learn more about lean-to trellises and other designs in my article here. Another option is to plant vining crops, such as cucumbers, at the bottom of a lean-to trellis. Celery is a Mediterranean plant that grows best in temperate climates with temperatures between 59 and 70° Fahrenheit (15-21° Celsius). Advisers at the University of Illinois Extension say the best planting temperature is fifteen degrees Celsius. Lettuce germination and early growth rates are largely determined by temperature. Lettuce. If you see an elongated crown on the lettuce plant, pull it up and compost. Lettuce seeds can germinate just fine at higher temperatures that would cause established lettuce plants to bolt (produce seeds and become bitter). This shade cloth from Gardener’s Supply Company can be used with hoops for support. The following methods will all help with this to some degree (no pun intended!). Lettuce is a cool-weather crop and a garden favorite, since it is the basis of many delicious salads. Temperature and light to grow lettuce Average room temperature of 16 to 21 degree Celsius is best for growing lettuce. Use this chart to determine if the soil temperature in the garden is right for seed starting the crop you want to plant. learn more about Cherokee lettuce from Johnny’s Selected Seeds. Depending on its variety, lettuce seed can germinate when the soil temperature is 35 to 80 degrees Fahrenheit. Leafy Lettuces. Sow 3 seeds per pot in 2-inch pots. Lettuce seed often refuses to germinate if the temperature is above 80 F. During hot weather, you can start lettuce seed indoors under lights, if your home has air conditioning. Just click the "Read More" button to the right. If direct seeding your lettuce seeds, thin the plants after they reach the seedling stage by pulling out some of the seedlings to leave enough space between the remaining plants. Frost damage on leafy vegetables doesn't render the plant inedible like a disease. Lettuce seeds are another leafy vegetable that is easy and quick to grow. Plants with one or two true leaves transplant best. Most cool season crops germinate at maximum soil temperatures of 90 degrees, except for lettuce and spinach, which require temperatures … Then, plant lettuce below the trellis. To grow onions, you will need the right conditions, including light and temperature. ... (e.g. All lettuce varieties are considered cool-season vegetables. For example, you can bend a flexible plastic rod into a half-circle and drive the two ends into the ground. This is a normal part of a lettuce plant’s life cycle. It’s past its prime. The best temperature for growing lettuce is from 55 up to 70 degrees Fahrenheit (12.8 to 21.1 degrees Celsius). First, you can plant your lettuce next to taller plants. Let's solve your gardening problems, spend more time growing, and get the best harvest every year! The soil should be kept moist at all times during the germination period. For example, lettuce seeds can still germinate in soil close that is close to freezing, but it will take several weeks to do so. Lettuce seeds typically sprout in two to eight days when soil temperatures range between 12 to 17 degrees Celcius. There is nothing I love more than heading out to my garden to pick fresh, crisp greens and bringing it indoors to make a salad. According the North Carolina State University Extension, lettuce will start to bolt (flower and make seeds) at daytime temperatures of 70 to 80 degrees Fahrenheit (21 to 27 degrees Celsius). Since a cloche is clear, it still allows sunlight in so that plants can continue to grow. Benjamin Shorter has been a writer for publications such as the "New Brunswick Telegraph-Journal," "National Post" and the "Edmonton Journal" since 2001. Growing your own lettuce is a beautiful thing. They can grow in … According to the Michigan State University Extension, lettuce is a plant that is hardy to hard frost. You would need to drape a frost blanket or piece of row cover over the cloche to insulate the plant. Just remember that lettuce do need some sunlight, so don’t leave your plants covered all day in heavy shade. Lettuce seeds are small, so … Day length affects onion growth and bulb development, but onion temperature tolerance depends on the... link to What Are Pelleted Seeds? If, however, you plan to harvest only small, tender leaves, then you can have more plants with less space between them. Shade cloth still allows some light to get through, which means that your lettuce will still be able to grow. One way to use row covers is to first install supports along a row and then drape the row cover over the supports. Now you know the ideal temperature ranges for lettuce germination and growth. After germination, the ideal temperature for growing lettuce is 55 to 65 degrees Fahrenheit (13 to 18 degrees Celsius). ~Jonathon. If you want to read some of my most popular posts, check out the “Best of GreenUpSide” page here. Most will check both the maximum temperature (usually during the day) and the minimum temperature (at night), so leave them in place for 24 hours for a complete picture. Lettuce seedlings are available at farmer's markets, nurseries and home garden centers, and lettuce also can be grown through direct seeding in the soil of a garden bed or growing container. If the lettuce gets too hot it will bolt, or flower, which isn’t good because this will create a bitter taste in the lettuce leaves. Here are some types of heat-tolerant lettuce from Johnny’s Selected Seeds: Any lettuce that gets partial shade during the hottest part of the day will take longer to bolt. According to the Michigan State University Extension, lettuce is a plant that is hardy to hard frost. You can protect an entire row of lettuce plants from cold by using a row cover. For example, you can leave extra space between your tomato plants and put a head of lettuce between every pair of tomato plants. Lettuce can survive in temperatures down to 10 degrees Fahrenheit or -12 degrees Celsius. Not only is it rewarding to pick your own fresh produce, but once picked, lettuce will continue to grow, giving you successive harvests of fresh greens. In other areas, it's considered the peak of the growing season when it's temperature x, and the same kinds of plants seem to thrive. Ideal Temperature for Lettuce to Grow. (The upper temperature limit to grow heading lettuces is 28°C/83F) So plant more seeds than the number of lettuce plants you need. So, what is the best temperature for growing lettuce? A cloche acts as a mini greenhouse, trapping heat from sunlight in the air and soil underneath it. Lettuce is a cool weather crop, so it prefers cooler temperatures for its growth. Lettuce thrives in the cool spring season so it requires planting in early spring once soil temperatures are above 60 degrees Fahrenheit. Take care that the temperature is not too high as lettuce starts to seed quickly under the influence of very hot temperature. This can make the difference for their survival when extreme cold is on the horizon. On the other hand, if the weather gets progressively cooler over a long time period, lettuce will be able to survive cold down into the 20’s Fahrenheit (-6 to -2 Celsius). learn more about lean-to trellises and other designs in my article here. Temperatures above that point quickly facilitate bolting. If you harvest your lettuce as it matures, you can extend your growing season by at least a few days. Are there varieties of iceberg lettuce and cabbages that can grow on low altitudes of less than 1000 feet and temperatures ranging 28 to 33 degrees Celsius along the equator (tropical climate) Ali April 26, 2018 For example, there are many heat-tolerant lettuce varieties that can withstand warmer temperatures than their cousins before they begin to bolt (more on these varieties later). Once a lettuce plant starts to produce seeds, the leaves will become bitter. During germination, the first root and shoot of lettuce emerge from the seed and move downward and upward, respectively. Thin to one or two plants per pot. Lettuce is a cool-season crop that prefers temperatures of 55 to 65 °F for optimum growth. learn more about Coastal Star lettuce from Johnny’s Selected Seeds. As the cucumbers grow, they will provide shade for the lettuce. Pelleted seeds make it much easier to sow the smallest seeds.So, what are pelleted seeds? Scratch the surface, or lightly cover the seeds with a sprinkling of soil. You can learn more about cloches in my article here. There is an ideal temperature range for growing lettuce, and extreme cold or heat will lead to poor growth or bitter leaves. We used the following techniques to successfully grow lettuce … Not all seeds germinate and lead to plants. (Plus 7 Heat Tolerant Varieties). If the lettuce leaves get large enough, the plant will think it is “done” growing, and will enter the next phase of its life: producing seeds. Keep lettuce plants protected, either by cold frames, hoops or tunnels. Lettuce may grow on different kinds of soil. Temperatures inside a covered seed tray will be closer to the maximum temperature reading and, unless the spot cools off considerably at night, will remain quite stable, a further factor to consider. Shade cloth is another method you can use to keep lettuce cooler. Lettuce seed will germinate at 35°F, but optimum germination is 70 to 75°F. In a natural environment cannabis does not thrive submerged in water: it prefers alternate wet/dry climate (which we replicate with the wet dry cycle when growing in soil or coco-perlite) in order to drag oxygen into its root system and thereby into the plant. It grows in any location with the sun and you can start indoors. Intense sunlight for 12 to … The best time to plant the seeds is during cool weather. You can make a cloche out of a clear plastic bottle by cutting out the bottom and using the cap on top as a vent. Space these half-circles a couple of feet apart in a row and you can cover them with a row cover, giving you a miniature “hoop house”. Germinating lettuce seeds is not difficult, but the task has some environmental requirements. You can combine two or more of these methods to keep your lettuce even cooler and extend the season to enjoy a longer harvest. A row cover is a piece of fabric material that protects plants against cold and pests. Experts say lettuce is one of the easiest vegetables to grow in your garden. learn more about Adriana lettuce from Johnny’s Selected Seeds. Storage temperatures for fruits and vegetables. Although lettuce can survive a hard frost, this assumes that the plant has proper conditioning. Regulating the temperature is another good way to improve the health of the plant. In this temperature range, lettuce seed takes only 2 to 4 days to germinate. A hard frost is defined as a temperature less than 28 degrees Fahrenheit (-2 degrees Celsius). As there are many varieties of lettuce, make sure you choose the ones that tolerate heat and grows well in tropical conditions. Lettuce may bolt in response to the stress of high temperatures, and the leaves may become bitter as the plant puts its growth into flowering (see photo at right). In fact, according to the Texas A&M University Extension, lettuce can even survive a frost or hard freeze, as long as the cold does not come suddenly after warm weather. The best temperature for growing lettuce will depend on the growth stage. A cool-weather vegetable, lettuce (Lactuca sativa) has many varieties, and they all germinate and grow best in cool temperatures, such as those in U.S. Department of Agriculture plant hardiness zones 4 through 9. ... Are Onions Heat Tolerant? One of the best ways to grow lettuce for a longer time period in a hot climate is too choose a heat-tolerant lettuce variety. learn more about Magenta lettuce from Johnny’s Selected Seeds. (3 Things To Know). You can harvest non-damage parts by cutting away brown areas and edges that are frost damaged and save just the leaf parts that are uninjured and your plant will continue to grow. At 70 to 80°F, the plants flower and produce seed. I hope you found this article helpful. However, this isn’t the only way to do it. Be careful when hardening-off plants not to expose them to cold temperatures. The first step is to choose lettuce that will work with you to resist bolting in the heat, so we’ll start with heat-tolerant lettuce varieties. The optimum soil temperature for seed germination is 60 to 8… To grow lettuce in hot climates, you will need a way to keep the lettuce a bit cooler. Harvested fruit and vegetables are living organisms. to read some of my most popular posts, check out the “Best of GreenUpSide” page here. You can also make a cloche out of wire (such as chicken or rabbit wire), although this will not provide cold protection by itself. Hi, I'm Jon. Finally, keep harvesting your lettuce as soon as the leaves are ready (or even when they are still a bit small!) But what happens when temperatures dip toward the freezing mark? Suitable air temperatures range from 12 – 21C, with 18C the optimum. Of course, if the temperature is too high or too low, lettuce seeds will fail to germinate. That is, the plant will start to grow tall and produce flowers, which will eventually produce seeds. Leaves wilt, toughen, and get bitter if the plant becomes water stressed in heat. Conditioning means that the plant has had time to grow accustomed to cooler temperatures, instead of being subjected to extreme cold all at once. That would be 77 degrees Fahrenheit.