Radishes are a relatively low maintenance crop, usually harvested in five to ten weeks, and you can harvest both the roots and leaves at the same time. Start with planting and plan to grow radishes in spring or fall! You can grow seeds in seed trays in greenhouse, plant earlier, harvest more.
Water as needed. Radishes need 1 inch (2.5cm) of water per week. A little less water can make the roots hard and bitter, but too much water can cause radishes to rot. At the mean time, you need to monitor local precipitation. During seasons with average rainfall, you don’t need to water. If it is dry season, you should water the radishes yourself.
Add a layer of plant cover. When the plants grow to 5 inches tall, place a 2-inch layer of mulch around the leaves. Place cover retains moisture, which can promote plant grow better and healthy. What’s more, mulch help control and limit the growth of vegetable garden weeds.
Consider fertilizing radishes. While fertilizing is not necessary, a monthly application of a mild organic fertilizer can make radish roots stronger. Choose fertilizers rich in potassium and phosphorus, not nitrogen-rich. Nitrogen fertilizer will encourage radish leaves to grow especially lush, but the roots will be bad. Look for fertilizers that also contain boron, or apply a boron spray alone four to six weeks after planting. Make sure any fertilizer you apply will keep four food safe. Instead of fertilizer, you can also use a dose of compost tea a month or so.
Weeding. Any weeds that poke through the mulch should be pulled with bare hands. Do not use herbicides, as chemicals can get into the radish and damage it, and make it inedible.
Watch out for pests and fungi. Root maggots and flea beetles are both the most common pests you need to be aware of, while powdery mildew and downy mildew are the most common fungi. Root maggot problems often arise when radishes are replanted in soil that has been planted with radishes, turnips, or rutabagas the previous year. To prevent root maggot infestations, use a crop rotation system and treat the soil with pesticides designed to fight root maggots and not harmful to food.Keeping your soil pH above 3.0 inhibits most problems caused by mold and other fungi, such as clubroot. Regularly test soil pH with a pH soil tester or sample at your local university extension office. Generally speaking, once a radish root is infected by a pest or fungus, there is little chance of it being salvaged. Your best bet is to remove the infected radishes and treat the soil as needed to annihilate as many pests or fungi as possible.