If you are planning on growing radishes in your garden this year, you might\nbe wondering 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 radishes.\n\n\n\nSo, how big do radishes get? Radish\nplants grow 4 to 14 inches (10.2 to 35.6 centimeters) tall, 3 to 14 inches (7.6\nto 35.6 centimeters) wide, and produce roots that are 1 to 4 inches (2.5 to\n10.2 centimeters) in diameter. Some tall\nradish varieties, such as Daikon, can have roots as long as 8 to 14 inches (20.3\nto 35.6 centimeters)!\n\n\n\nOf course, the quality of your radishes (if you get any at all!) depends on\nthe care that you give your plants. Let\u2019s take a closer look at radishes,\nincluding size, growing conditions, and time to maturity.\n\n\n\nHow Big Do Radishes Get?\n\n\n\nRadish greens (the stalks and leaves) can grow to a height\nof 4 to 14 inches (10.2 to 35.6 centimeters) above the soil, with a width of 3\nto 14 inches (7.6 to 35.6 centimeters).\n\n\n\nThe greens of radish plants can grow much taller than the roots themselves.\n\n\n\nThe roots of many small, round radish varieties may only be\n1 to 2 inches (2.5 to 5.1 centimeters) in diameter. Some larger round radishes can grow to 3 or 4\ninches (7.6 to 10.2 centimeters) in diameter.\n\n\n\nHowever, you will want to harvest your radishes before they\ngrow too large. Otherwise, you will get\nradishes with a bitter flavor.\n\n\n\nThe tallest radish varieties, such as Daikon, are longer and\nthinner, and can get into the range of 8 to 14 inches (20.3 to 35.6\ncentimeters).\n\n\n\nHow Long Does It Take Radishes to Grow?\n\n\n\nSome radishes can grow to maturity in as little as 20\ndays! However, most radishes will take\n20 to 40 days to mature.\n\n\n\nSome radishes can mature in as little as 20 days, while some can take up to 70 days.\n\n\n\nHowever, there are certain varieties, such as Daikon\nradishes, that can take up to 60 or 70 days to mature.\n\n\n\nAccording to Michigan State University, radish seeds will germinate in 3 to 10 days, assuming proper moisture and ideal soil temperature of 65 to 85 degrees Fahrenheit (18.3 to 29.4 degrees Celsius).\n\n\n\nHow Do You Know When to Pick Radishes?\n\n\n\nFor most radish varieties, you can harvest them when the roots are 1 inch (2.5 centimeters) in diameter at the surface of the soil.\n\n\n\nFor more information, check out this article on radishes from the Old Farmer's Almanac.\n\n\n\nMost radishes are ready to harvest when the roots are 1 inch or so in diameter at the surface of the soil.\n\n\n\nKeep an eye on your radishes, since they mature and grow\nvery quickly! Check on them daily when\nthey get close to maturity (look at the seed packet to get an idea of the days\nto maturity).\n\n\n\nWhy Are My Radishes So Small?\n\n\n\nRadishes will grow small if you provide too much nitrogen in\nthe soil or give the plant too much shade.\n\n\n\nIn both cases, the radish plant will grow large leaves at\nthe expense of the root. Avoid adding\ntoo much nitrogen or planting radishes in the shade of trees and other tall\ncrops in your garden.\n\n\n\nWhat Do Radishes Look Like?\n\n\n\nRadishes are roots that grow in the ground. Some are small and round, while others are\nlonger and more similar in shape to carrots.\n\n\n\nRadishes can be red, purple, white, or black on the\noutside. Radishes are usually white on\nthe inside, although some have purple or red color inside.\n\n\n\nRadishes can be red, purple, white, or black on the outside, and are usually white on the inside.\n\n\n\nRadishes send up stalks with leaves on them (greens). These greens can be used in salads, but you\nwill want to harvest when they are young and tender for this purpose.\n\n\n\nOtherwise, you can boil or steam radish greens, similar to\nhow you would use spinach or beet greens.\n\n\n\nAre Radishes Hard to Grow?\n\n\n\nRadishes like full sun, so make sure you do not plant them\nin the shade of trees or other crops in your garden. Otherwise, you will get radish plants with\nlarge leaves and small roots.\n\n\n\nLike carrots, radishes are grown mainly for the roots, which\nneed loose, sandy soil to grow without obstruction.\n\n\n\nThere are many other factors that affect radish growth, including\ntemperature, watering, fertilizing, and spacing. Let\u2019s start with\ntemperature.\n\n\n\nTemperature for Radishes\n\n\n\nThe minimum temperature for radish seed germination is 40 degrees Fahrenheit\n(4.4 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 radish seeds from sprouting at a time\nwhen they will be unable to survive. This is why it is suggested that you\nstart radish seeds indoors to avoid cold soil temperatures in early spring.\n\n\n\nThe maximum temperature for radish 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 radish seeds and transplant your established plants outside!\n\n\n\nThe Old Farmer\u2019s Almanac suggests sowing radish seeds directly into the soil\noutdoors, 4 to 6 weeks before the last spring frost date.\n\n\n\nYou can find the frost dates for your area on the Old Farmer\u2019s Almanac\nwebsite.\n\n\n\nYou can start seeds indoors if the growing season is short where you\nlive. However, remember that it is easy\nto disturb the roots of radishes when transplanting them outside.\n\n\n\nThe ideal (optimal) temperature for radish seed germination is between 65\ndegrees Fahrenheit (18.3 degrees Celsius) and 85 degrees Fahrenheit (29.4 degrees\nCelsius).\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 radish 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\nSeed Germination TemperatureTemperature (degrees Fahrenheit)Temperature (degrees Celsius)Minimum404.4Ideal65 to 8518.3 to 29.4Maximum9535\n\n\n\nWatering for Radishes\n\n\n\nRadishes need plenty of water, and they need even moisture\nlevels to develop properly. Periods of\ndry soil followed by too much water will cause radishes to split or develop a\nbitter flavor.\n\n\n\nMake sure to water radishes evenly to avoid splitting and a bitter flavor.\n\n\n\nPutting mulch on top of your soil will help to retain moisture, especially\nduring periods of hot, dry weather. If\nyou find that you have a problem with dry soil, check out my article on how to treat dry soil.\n\n\n\nOn the other hand, over watering your radish 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. Avoid getting the leaves wet to prevent rot, mold,\nand diseases.\n\n\n\nFertilizing for Radishes\n\n\n\nAccording to Burpee, you should avoid adding too much nitrogen to your soil when growing radishes. Otherwise, you will get lots of green growth (stalks and leaves) but small roots.\n\n\n\nFor more information, check out my article on over fertilizing your plants.\n\n\n\nAdding compost to your soil before planting is a good way to improve drainage for clay soil, improve water retention for sandy soil, and add nutrients to your garden.\n\n\n\nFor more information, check out my article on making compost.\n\n\n\nCompost adds organic material and nutrients to your soil, and can be made by recycling kitchen scraps and yard waste.\n\n\n\nSpacing for Radishes\n\n\n\nSow radish seeds directly into the garden, at a depth of 0.25\nto 0.5 inches (0.6 to 1.3 centimeters).\n\n\n\nFor more information, check out this article on radishes from the University of Illinois Extension.\n\n\n\nThin the radish plants to 1 inch (2.5 centimeters) apart for\nspring varieties, and 2 to 4 inches (5.1 to 10.2 centimeters) apart for winter\nvarieties. Do your thinning when the\nradishes are a week old (or when they have two sets of true leaves).\n\n\n\nBe sure to thin your radish seedlings to prevent overcrowding and competition between plants.\n\n\n\nFor more information, check out my article on thinning seedlings.\n\n\n\nYou can plant radishes in the spring (May) to get a first\ncrop, and also get a fall crop by planting in late summer (August).\n\n\n\nConclusion\n\n\n\nNow you have a much better idea of how big radishes get, in terms of both the root below ground and the stalks above ground.\u00a0 You also know a bit more about the care that is necessary to ensure a healthy crop of radishes in this year\u2019s garden.\n\n\n\nYou might also want to read my article on fall planting for cool weather crops.\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 radishes, please leave a comment below.