Scientific Name: Raphanus raphanistrum subsp. sativus
Common Names: Radish 'Hailstone', Radish 'White Globe'
The exact origin of this heirloom hailstone radish variety is unknown, but it has been offered by seed merchants since at least 1908.
Hailstone is one of the mildest and sweetest heirloom radish varieties available so is a good choice for people who don't normally enjoy the spicy pungency of other radishes. Hailstone radishes have crisp white flesh and a smooth white skin. This variety forms attractive, globe-shaped roots about 5cm in diameter. Hailstone radishes are delicious when sliced thin and added raw to salads or sandwich, or when preserved in a seasoned pickling liquid. Radishes can be cut into wedges and cooked by briefly steaming or stir-frying although they'll loose a lot of their flavour. Radish leaves are also edible as a green vegetable but are best picked small as they become spiny when left to grow to full size.
Hailstone radishes will grow and produce best planted in a full sun location, however gardeners in warmer climates may prefer to grow them in a lightly shaded position to reduce heat stress during the hottest part the day. Hailstone radishes bolt quickly in exceptionally hot weather. The roots of radishes that have bolted to seed will stop growing and become bitter and woody, therefore this variety is best grown in temperate or cold climates, or during the Winter in warmer climates. Hailstone radishes grow best in free-draining, fertile soil rich in organic matter. If you soil is sandy, heavy with clay or pale and lacking in organic matter you can improve it by placing down a layer of compost or well-rotted manure prior to planting radishes. Worms and soil micro-organisms will incorporate the organic matter through your garden soil improving its structure and fertility. Radishes are not heavy feeders and too much nitrogen will result in a heavy leaf production with very little root growth so don't apply any supplementary fertiliser, the organic matter placed down at the start of the growing season should be sufficient. Radishes grow quickly and require consistent watering. Radishes that are left to dry out for too long will have cracked and split roots that are woody. Mulch around radish plants to help retain soil moisture and keep their roots cool. Radishes are frost hardy but should be sheltered from cold winds with a windbreak if growing in cooler climates.
When to Sow
In cold, temperate and subtropical areas of Australia you can sow hailstone radish seeds any time of year, although their flavour will be milder and sweeter if grown during cooler weather. In tropical areas of Australia hailstone radish seeds should be sown during the dry season from mid Autumn through to mid Winter.
How to Sow
Sown hailstone radish seeds 1cm deep. Radishes produce best if sown directly where they are to grow, transplanting seedlings will often damage the roots causing stunted growth. Space hailstone radish plants about 10cm apart to give their roots room to expand and facilitate airflow between plants. Radishes planted too closely together will grow oddly-shaped roots if they are in contact with each other.
Hailstone radish seeds will germinate quickly and consistently with most seedlings emerging 3 to 12 days after sowing. Radishes typically germinate much quicker than other vegetables so are sometimes sown as rows markers at the ends of other crops.
Time to Harvest
Hailstone radishes take from 6 to 8 weeks to produce full-sized roots that are ready to harvest. Pick radish roots as soon as they are large enough as they'll become woody if left in the ground for too long.