If you garden in a dry area you'll love this idea. Make your own olla. What's an olla? "An Olla is an ancient watering pot, that is buried in the ground in the area that you put your plants, when the plants need water the roots suck the water from the Olla."
How to Grow Radishes: Easy Growing Guide: Organic Gardening. Make weekly spring sowings as soon as you can work the soil (4 to 6 weeks before the last expected frost) until early summer; start again in late summer. Sow winter radishes in midsummer for a fall harvest.