Radish Seeds,
Purple Plum

Purple Plum radishes are cool-season crops that perform best when grown in early spring. They can be sown 4 weeks before the last expected spring frost. Ideal growing temperatures are between 50-75 F, with temperatures in the low 60s being optimal. Higher temperatures can cause radishes to bolt, reducing the quality of the roots​. If you’re not sure how to find your first and last frost dates, consult our blog post 'Our Experts Answer Questions, Share Resources.'

Plant the seeds directly in the garden about 1/4 inch deep and 1 inch apart in rows spaced 3 inches apart. Once seedlings emerge, thin them to 2 inches apart to prevent overcrowding, which can hinder root development. You can also sow spring radishes in several small successions for a continuous harvest.

Water the radishes consistently, aiming for about 1 inch of water per week to maintain soil moisture and promote bulb development. Using mulch around the plants can help retain moisture and reduce weed growth, creating a more stable environment for the radishes to grow. Fertilization isn't generally required if the soil is already fertile, but a balanced, low-nitrogen fertilizer can be used sparingly to support growth​.

• Radishes are insect-pollinated, so you'll need to isolate varieties by up to 1⁄2 mile or stagger plantings to avoid flowering at the same time.
• Staggering can be easy because of the radish's quick maturity.
• Allow flower stalks to shoot up and seed pods to dry on the plant before picking pods and opening by hand to remove the seeds.
• Seeds will remain viable for up to 5 years when stored in an airtight container.