If you are planning on growing leeks in your garden this year, you might be\nwondering how big they will get. That way, you can plan the number of\nplants and the amount of space you will need for your crop of leeks.\n\n\n\nSo, how big do leeks get? The\nstems of leeks are 6 to 12 inches\n(15 to 30 centimeters) long and 1 to 2 inches (2.5 to 5 centimeters) in\ndiameter. The leaves of leaks can grow\n12 to 24 inches (30 to 61 centimeters) tall with a spread of up to 12 inches\n(30 centimeters). Overwintering leeks are generally larger than summer\nleeks, and have a stronger flavor.\n\n\n\nOf course, the quality of your leeks (if you get any at all!) depends on the\ncare that you give your plants. Let\u2019s take a closer look at leeks,\nincluding size, growing conditions, and time to maturity.\n\n\n\nHow Big Do Leeks Get?\n\n\n\nLeek stems (the part grown underground that is normally\neaten) grow 6 to 12 inches (15 to 30 centimeters) long, with a diameter of 1 to\n2 inches (2.5 to 5 centimeters) at harvest.\n\n\n\nLeek stems can grow 6 to 12 inches (15 to 30 centimeters) long. Although related to onions, leeks are much longer and thinner.\n\n\n\nThe leaves of a leek plant grow up from the stem and can\nreach a height of 12 to 24 inches (30 to 61 centimeters) above the soil, with a\nspread of up to 12 inches (30 centimeters).\n\n\n\nLeeks are a member of leek family (allium), but they are\ngenerally smaller than leeks. Leeks are\noften classified into summer leeks and overwintering leeks.\n\n\n\nSummer leeks are smaller, and overwintering leeks have a\nstronger flavor. They can be harvested\nearly and used similarly to shallots.\n\n\n\nHow Long Does It Take Leeks To Grow?\n\n\n\nLeeks can take 130 to 160 days to go from planting a seed to\nharvesting a mature leek stem.\n\n\n\nLeeks usually take 14 to 21 days to germinate, assuming ideal conditions (consistently moist soil and the right temperature \u2013 more on this later).\n\n\n\nLeeks are often sown directly into the ground. If you start them indoors, they should be\nstarted 8 weeks (56 days) before transplanting them outdoors.\n\n\n\nHow Do You Know When To Harvest Leeks?\n\n\n\nYou should harvest a leek when the stem (at the base of the leaves)\nreaches 1 to 2 inches (2.5 to 5 centimeters) in diameter. This will be 130 to 160 days after direct\nplanting, or 75 to 100 days after transplanting outdoors.\n\n\n\nLeeks should be harvested when they are 1 to 2 inches (2.5 to 5 centimeters) in diameter.\n\n\n\nTo harvest leeks, cut the roots below the stalks (leaves). Then, twist the stalks back and forth until they are loose and pull them up out of the ground. Cut off remaining roots and all but 2 inches of the leaves.\n\n\n\nFor more information, check out this article on leeks from Burpee.\n\n\n\nWhy Are My Leeks So Small?\n\n\n\nOne reason that your leeks are growing thin is due to overcrowding. If you plant them too close together and fail to thin young plants, they will compete for water and nutrients in the soil.\n\n\n\nIf you plant your leeks too close together, overcrowding may result in smaller stems.\n\n\n\nLeeks may also grow small due to water stress (dry soil due\nto drought) or lack of nutrients (especially nitrogen).\n\n\n\nAssuming that the plant spacing, watering, and nutrition are\nall in order, there is one way to get larger leek stems. Plant the leeks in a trench 8 to 12 inches\n(18 to 30 inches) deep and cover the stem with soil as the leek grows.\n\n\n\nWhat Do Leeks Look Like?\n\n\n\nThe University of Minnesota describes leeks as overgrown green leeks, with a long white shaft (shaped like a cylinder).\n\n\n\nThe leaves of leek plants are thick, flat, and blue-green in\ncolor.\n\n\n\nAre Leeks Hard To Grow?\n\n\n\nLeeks like full sun, so be sure to plant them in an area where they get 8 or\nmore hours of sunlight per day. Avoid planting leeks in a place where\nthey will be completely shaded by a tree or tall neighboring plants (such as\ntomatoes).\n\n\n\nLeeks grow best in well-drained soil with a pH of 6.0 to 7.0 (slightly\nacidic). However, there are many other factors that affect leek growth,\nincluding temperature, watering, fertilizing, and spacing. Let\u2019s start\nwith temperature.\n\n\n\nTemperature for Leeks\n\n\n\nThe minimum temperature for leek seed germination is 32 degrees Fahrenheit\n(0 degrees Celsius). If the soil is any colder than this, you will see\nlow germination rates \u2013 that is, if you can get any seeds at all to germinate!\n\n\n\nThis is nature\u2019s way of protecting leek seeds from sprouting at a time when\nthey will be unable to survive. This is why it is suggested that you\nstart leek seeds indoors to avoid cold soil temperatures in early spring.\n\n\n\nThe maximum temperature for leek seed germination is 95 degrees Fahrenheit\n(35 degrees Celsius). If the soil is any warmer than this, germination\nrates will decrease.\n\n\n\nCombined with high humidity, high temperatures can encourage the growth of\nmold, which is another threat to your plants. So, don\u2019t wait too long to\nplant your leek seeds and transplant your established plants outside!\n\n\n\nLeek seeds are often sown directly into the soil outdoors, 2 to 4 weeks before the last frost. You can find frost dates for your area on the Old Farmer\u2019s Almanac website.\n\n\n\nHowever, this may not be an option in a climate with a short growing\nseason. In that case, you should start your\nleek seeds indoors 8 weeks before transplanting them into the garden.\n\n\n\nLeeks should be transplanted when they are 6 to 8 inches (15 to 20 centimeters) tall. For more information, check out this article on leeks from the Old Farmer\u2019s Almanac.\n\n\n\nThe ideal (optimal) temperature for leek seed germination is between 65\ndegrees Fahrenheit (18.3 degrees Celsius) and 85 degrees Fahrenheit (29.4\ndegrees Celsius).\n\n\n\nKeep in mind that these temperatures refer to soil temperature, not air\ntemperature. If you want to find out the soil temperature, use a\nprobe-type thermometer to check.\n\n\n\nIf the thermometer reads a temperature that is too low, then you have some\noptions. One option is to wait until the sun warms up the soil.\n\n\n\nTo speed up this process, clear away any debris, such as leaves or grass\nclippings, from the soil surface. Also make sure to choose a location for\nplanting that gets plenty of sun, so that it can warm up the soil faster.\n\n\n\nIf you are worried about a short growing season, you can also use a cloche\n(a plastic or glass cover) to trap some heat and warm up the air and soil near\nyour leek seeds.\n\n\n\nA cloche can be made from a plastic water bottle to retain warmth and\nhumidity in the soil for seeds or seedlings as they grow. \n\n\n\nFor more information, check out the table below, and check out this\narticle from the University of California on ideal seed germination\ntemperatures.\n\n\n\n\n Seed \n Germination \n Temperature \n \n Temperature \n (degrees \n Fahrenheit) \n \n Temperature \n (degrees \n Celsius) \n \n Minimum \n \n 32 \n \n 0 \n \n Ideal \n \n 65 to 85 \n \n 18.3 to 29.4 \n \n Maximum \n \n 95 \n \n 35 \n \n\n\n\nLeeks mature best at temperatures below 75 degrees Fahrenheit (23 degrees Celsius). For more information, check out this article on leeks from Clemson University.\n\n\n\nWatering for Leeks\n\n\n\nLeeks need regular watering to maintain moist soil. You may need to water more often if your soil\nis sandy (which means that it will drain quickly).\n\n\n\nYou may need to water frequently to keep the soil moist for optimal leek growth.\n\n\n\nPutting mulch on top of your soil will help to retain moisture, especially\nduring periods of hot, dry weather. If you find that you have a problem\nwith dry soil, check out my article on how to treat dry soil.\n\n\n\nOn the other hand, over watering your leek plants (or any plants for that\nmatter) can lead to root rot and eventual death. The best way to decide\nwhen to water is to feel the soil with your fingers.\n\n\n\nIf the soil feels dry 2 or 3 inches below the surface, then go ahead and\nwater. For more information, check out my article on over watering your plants.\n\n\n\nTry to water early in the morning, rather than at night, to allow water to\nsoak into the soil before evaporating.\n\n\n\nFor more information, check out this article on growing leeks from the University of Minnesota Extension.\n\n\n\nFertilizing for Leeks\n\n\n\nAdding compost to your soil before planting leeks is a good way to improve\ndrainage for clay soil, improve water retention for sandy soil, and add\nnutrients to your garden.\n\n\n\nCompost adds nutrients and organic material to your soil, and can be made from recycled kitchen scraps and yard waste.\n\n\n\nFor more information, check out my article on making compost.\n\n\n\nAccording to Utah State University, leeks require plenty of nitrogen, so consider using a fertilizer such as 16-16-8 at a rate of 1 to 2 pounds per 100 square feet.\n\n\n\nYou can also side dress with nitrogen-rich fertilizer, but\nbe careful not to burn your plants, especially if using manure in your garden.\n\n\n\nFor more information, check out my article on over-fertilizing your plants.\n\n\n\nSpacing for Leeks\n\n\n\nLeeks should be planted 0.5 inches (1.25 centimeters) deep\nif direct seeding. Leeks should later be\nthinned to leave 4 to 6 inches between plants.\n\n\n\nLeave 24 inches between rows, to allow space for watering, fertilizing, weeding, and harvesting. For more information, check out this article on leeks from the University of Maryland Extension.\n\n\n\nConclusion\n\n\n\nBy now, you have a much better idea of how big leeks get. You also\nknow a bit more about the care that is necessary to ensure a healthy crop of leeks\nin this year\u2019s garden.\n\n\n\nI hope you found this article helpful \u2013 if so, please share it with someone\nelse who can use the information. If you have any questions or advice\nabout leeks, please leave a comment below.