Sparkler Organic Radish Seeds 4162 Heirloom Vegetable. There is no doubt about it, Sparkler is a beautiful round summer radish. The top half is a fine scarlet colour with a rosy â€˜sparklingâ€™ edge bordering a pure white bottom half. Tender yet crisp flesh on what is possibly the finest market radish offered. Irrigation is essential for best flavour and root development.