Why do radishes grow tops but no roots?

What's with radishes that have beautiful tops and scrawny little roots below? Arghhh! It's an annoying problem caused by three things: They were over-seeded, you've got too much nitrogen in your soil, or they're only getting watered "some of the time." I've seen whole crops become rootless due to this imbalance. Knowing why this happens is the first step in getting radishes with their heads on straight!

Overcrowding robs developing roots of needed nutrients and space in their effort to get bigger leaves, while their anchoring roots stay dwarfed. Summer varieties, where the plants grow close together, should always be thinned out to stand 2 inches apart. Apart, the winter kinds need a 4-6 ins. spacing. I use a measuring tape for accuracy. The weakest seedling, if there is one, is cut off with scissors to allow the others to develop at the expense of its strength.

NIOTROGEN IMBALANCE gives priority to the leaves at the expense of the roots. This condition is caused by the use of high-nitrogen fertilizers of any kind and the application of fresh manure. When growing radishes, it is essential to provide balanced nutrients and an adequate amount of phosphorus to promote root development. Use of composted manure only, certainly never fresh. In my soil, there is more nitrogen than is beneficial for the depth concerned. Root formation was delayed just 2 weeks. The use of bone meal eliminated the difficulty.

Soil consistency can have a great influence on radish. Compacted, or rocky, dirt literally prevents the radish from pushing through. Prepare the beds to a depth of 12 inches (30 centimeters) for winter varieties. Six inches (15 cm.) is sufficient for the summer types. I incorporate coarse sand for heavy clays. What this means is that you will have that loose, crumbly material radishes must have.

Watering methods avert failings due to stress. Roots split or pause when moisture levels vary, typically due to water from below, not on the leaves. Mornings are best for reducing evaporation. My moisture meter ensures an even supply at one inch (2.5 cm) per week. Containerized plants must be checked daily in heatwaves.

Preventive Measures: Test your soil before planting. Go for quicker maturing summer varieties until you know what you're doing. Rotate your planting location every year. I keep a garden journal where I note spacing and feeding schedules. Since we instituted these measures, I haven't had one radish that was devoid of roots.

Read the full article: How to Grow Radishes: Foolproof Guide