Colorful Radish Seeds – Purple Plum & Watermelon Radish

Purple Plum & Watermelon Radish Seeds for Planting – Non-GMO Heirloom Seeds (Raphanus sativus) offer a colorful combination of two distinctive radish varieties with contrasting appearances, flavors, and maturity periods. Purple Plum produces smooth, round roots with vibrant purple skin and crisp, snow-white flesh. Its approximately 1½-inch roots have a pleasantly mild, sweet flavor and maintain a firm texture without becoming pithy as quickly as many traditional spring radishes. Watermelon Radish develops larger, round roots with creamy-white skin, pale green shoulders, and brilliant rose-pink interiors resembling miniature watermelons when sliced. Its crisp flesh offers a mildly sweet flavor with a refreshing peppery finish.

This attractive pairing provides both a quick spring radish and a larger specialty storage radish. Purple Plum is ideal for fast harvests, while Watermelon Radish requires a longer growing period and develops its best color and flavor during cool fall weather. Both varieties are excellent for fresh snacking, salads, sandwiches, vegetable trays, garnishes, pickling, roasting, sautéing, and decorative culinary presentations. Their striking purple, white, green, and pink colors make them especially appealing for farmers’ markets, home gardens, edible landscapes, and gourmet dishes.

Planting Season

Best planted in: Early Spring & Late Summer to Early Fall (Cool-Season Crops)

Sow Purple Plum Radish seeds outdoors as soon as the soil can be worked in early spring. Additional small plantings can be made every 7–14 days during cool weather to provide a continuous harvest. Purple Plum is frost hardy and grows best when temperatures remain between approximately 50–75°F (10–24°C).

Watermelon Radish may be planted in spring, but it generally performs best when sown in late summer for a fall harvest. Shortening days and cooler autumn temperatures encourage proper root development, mild flavor, and vivid pink interior color. Sow approximately 8–10 weeks before the expected first hard frost so the roots have sufficient time to mature.

Radish seeds can begin germinating when soil temperatures reach approximately 40°F (4°C), but faster and more consistent germination generally occurs between 55–75°F (13–24°C). Soil temperatures near 65–85°F (18–29°C) can produce rapid seedling emergence when adequate moisture is available. Avoid growing radishes through prolonged hot weather because excessive heat and drought may cause premature flowering, tough roots, pithy interiors, and an overly strong flavor.

How to Grow Purple Plum & Watermelon Radish Seeds

Direct sowing is strongly recommended because radishes form sensitive taproots and generally do not transplant well. Plant the seeds directly in their permanent garden bed, raised bed, or container.

Choose a planting location that receives full sun, ideally at least 6 hours of direct sunlight daily. In warm climates, light afternoon shade may help keep the soil cooler and extend the growing season, but excessive shade may encourage leafy growth without producing properly developed roots.

Plant in loose, fertile, well-drained soil with a pH between approximately 5.8 and 6.8. Remove rocks, roots, compacted clumps, and other debris that could restrict root development. Radishes grow best when their roots can expand easily through friable soil and receive consistent moisture.

Loosen the soil to a depth of approximately 6–8 inches for Purple Plum Radishes and at least 8–10 inches for Watermelon Radishes. Although both varieties produce round roots, the larger Watermelon Radish benefits from deeper soil preparation and additional space.

Sow seeds approximately ¼–½ inch deep. Planting near ¼ inch deep is suitable for heavier soil, while seeds may be planted slightly deeper in loose or rapidly drying soil.

Plant Purple Plum seeds approximately 1 inch apart and thin the seedlings to a final spacing of about 2 inches. Purple Plum develops compact, approximately 1½-inch globe-shaped roots and does not require extensive growing space.

Plant Watermelon Radish seeds approximately 1–2 inches apart and thin the seedlings to a final spacing of about 3–4 inches. The larger roots need more room to develop their characteristic rounded shape. Space rows approximately 12–18 inches apart to allow sufficient room for cultivation, watering, and harvesting.

Keep the soil surface consistently moist during germination, but do not allow it to become saturated or waterlogged. Seeds may germinate within approximately 3–10 days under favorable conditions. Purple Plum commonly sprouts within 3–6 days when grown at suitable temperatures.

Thin the seedlings promptly once they have developed their first true leaves. Crowded radishes often produce large leafy tops with undersized, misshapen, or undeveloped roots. Cut unwanted seedlings at soil level when necessary to avoid disturbing the roots of nearby plants.

Purple Plum and Watermelon Radishes grow as compact, upright plants and do not require stakes, trellises, or other support structures.

Both varieties can be grown successfully in containers. Choose a container at least 8 inches deep for Purple Plum and approximately 10–12 inches deep for Watermelon Radish. The container should have adequate drainage holes and be filled with loose, high-quality potting soil. Maintain the recommended spacing and check moisture frequently because containers may dry more quickly than garden beds.

Mix finished compost or well-aged organic matter into the upper soil before planting. Compost improves soil structure, drainage, and moisture retention. Avoid fresh manure and excessive nitrogen fertilizer because overly rich soil may produce vigorous leaves at the expense of properly formed roots.

For an extended harvest, sow small quantities of Purple Plum seeds every 7–14 days during cool weather. Watermelon Radishes mature more slowly and are usually planted as one or two late-summer sowings timed for an autumn harvest.

How to Care for Purple Plum & Watermelon Radish Plants

Water regularly throughout the growing period so the soil remains evenly moist. Radishes need rapid, uninterrupted growth to develop tender flesh and a mild, balanced flavor. Dry soil can slow root development and produce tough or excessively spicy radishes, while irregular watering may cause mature roots to split.

Avoid allowing the soil to remain soggy. Poor drainage and continuously wet soil can encourage root diseases, seedling loss, and decay. Raised beds are helpful in gardens with heavy clay soil or frequent rainfall.

Apply a thin layer of clean straw, shredded leaves, or finished compost around established seedlings. Mulch helps conserve soil moisture, suppress weeds, and maintain cooler, more consistent soil temperatures. Keep heavy mulch away from very young seedlings until they are firmly established.

Radishes generally require only moderate fertility. When planted in soil amended with compost, additional fertilizer may not be necessary. If growth appears weak, apply a light amount of balanced vegetable fertilizer. Avoid high-nitrogen products, which can encourage excessive foliage and poor root formation.

Keep the planting area free from weeds, especially while the seedlings are young. Pull weeds carefully by hand or cultivate only the upper surface of the soil. Deep hoeing can damage the developing roots and reduce harvest quality.

Monitor plants for flea beetles, aphids, slugs, snails, and root maggots. Flea beetles create numerous small holes in young leaves, while root maggots tunnel into the developing radishes. Lightweight floating row covers installed immediately after sowing can help prevent flying pests from reaching the plants.

Reduce disease problems by providing well-drained soil, adequate spacing, good airflow, and crop rotation. Avoid repeatedly planting radishes or other cabbage-family vegetables in the same location. Territorial Seed recommends a five- to seven-year rotation as a preventive measure for persistent Brassica diseases.

Purple Plum Radishes are typically ready for harvest approximately 26–30 days after sowing. Begin checking the roots when their purple shoulders become visible above the soil. Harvest when the roots are firm, smooth, and approximately 1–1½ inches in diameter.

Watermelon Radishes generally mature approximately 50–60 days after sowing. Harvest when the roots are firm, rounded, and approximately 2½–4 inches in diameter, depending on the strain and growing conditions. The exterior should be creamy white with pale green shoulders, while the interior should display vivid pink or rose-red coloring.

Do not leave mature radishes in warm soil for too long. Overmature roots may become fibrous, hollow, cracked, or excessively pungent. Watermelon Radishes can remain in cool fall soil longer than tender spring radishes, but they should be harvested before the ground freezes solid.

Loosen the surrounding soil before gently pulling large Watermelon Radishes. Purple Plum roots can usually be harvested by holding the leaves near the soil surface and pulling upward.

After harvesting, remove the leafy tops because they continue drawing moisture from the roots. Brush away excess soil and keep unwashed radishes in perforated or semi-permeable bags under cool, humid refrigerated conditions. Purple Plum is best enjoyed soon after harvest, while the denser Watermelon Radish has better storage potential. Properly topped radishes may retain good quality for approximately 3–4 weeks when stored near 32°F (0°C) with high humidity.

Shipping cost will be calculated based on your product and location. You can view the details during checkout.