How to Grow Radishes
Planning the Site
Choose a site that gets at least 6 hours of sun a day and has light, rich, well-drained soil with a pH of 5.8 to 6.8. For best growth use fertile, well-drained, and deep sandy soils rich in organic matter.
Preparing the Site
Till the soil to a depth of at least 6 inches. Remove any debris that could obstruct the growing tubers, and work in organic matter to ensure the right soil conditions. Before planting, incorporate up to 2 to 4 inches of well-composted organic matter and apply two to four cups of all-purpose fertilizer (16-16-8 or 10-10-10) per 100 square feet. Work this into the top 6 inches of soil.
Required Materials
Required materials include radish root crops, fertilizers, calcium sulfate, and calcium carbonate.
Watering Requirements
Water radishes regularly. Water requirements depend on soil type. Mulching around the plants helps to conserve soil moisture. Use drip irrigation if possible. Moisture fluctuations cause root cracking, slow leaf development, and contribute to “hot,” bitter roots. Stress during the first 6 weeks of growth often leads to premature flowering and low yields.
Nutrients Required
Liberal applications of animal manure are normally used for growing radishes. Apply good-quality fowl manure at the rate of 15 t/ha (1.5 kg/m2) 2 to 3 weeks before planting. Before sowing, broadcast 100 g/m2 of 5:5:5 N: P:K fertilizer. This ensures that the young seedlings have a ready supply of major elements immediately after germination. This is important for radishes as they have a short growing period.
Seasons
Spring radishes should be planted as early as the soil can be worked, which is usually until midspring. Make successive plantings in short rows every 10 to 14 days. Plant in spaces between slow-maturing vegetables (such as broccoli and brussels sprouts) or in areas that will be used later for warm-season crops (pepper, tomato, and squash). Spring radishes also can be planted in late winter in a protected cold frame, window box, or container in the house or on the patio. Winter radishes require a much longer time to mature than spring radishes and are planted at the same time as late turnips (usually midsummer to late summer).
Expectations/Results
Radishes can be harvested when the roots reach full size. Generally, roots mature 25 to 45 days after seeding, depending on the variety. Pull up plants by the tops and trim off leaves. Wash and store in plastic bags in a refrigerator for 2 to 4 weeks. Radishes should be harvested before heavy frost or freezes.