When you think of a radish (Raphanus sativus), you most likely imagine the root vegetable that's small, round, red, and tangy. The most popular radishes fit this description, though there are several varieties that differ in appearance. They can be round or oblong; hot or mild; red, pink, purple, white or bicolor.
Radishes are annual vegetables that are members of the Brassicaceae family, along with broccoli, cabbage, cauliflower, kale, and collards. They are planted in the spring (for a spring harvest) or late summer (for a fall harvest). And they have a quick growth rate. Some of the smaller varieties mature in as few as 30 days. The larger varieties can keep you waiting for up to 60 days.
|Common Name||Radish, common radish, garden radish, rabone|
|Botanical Name||Raphanus sativus|
|Plant Type||Annual, vegetable|
|Size||6 - 8 inches tall|
|Sun Exposure||Fun sun|
|Soil Type||Loamy, sandy, moist, well-drained|
|Soil pH||Acidic, neutral (6 to 7)|
|Hardiness Zones||2–11 (USDA)|
How to Plant Radishes
When to Plant
Direct seed radishes in the garden in the early spring as soon as the ground is workable. Because they mature so quickly, plant them weekly (succession sow) to ensure you have an ongoing supply of radishes. You also can plant them again toward the end of summer and early fall at least four to six weeks prior to your first fall frost. When spring temperatures reach 65 degrees, stop planting, as they will bolt in the heat.
Selecting a Planting Site
Pick a sunny spot with rich, loose, well-draining soil. Container growing is also an option. Because radishes grow quickly, they can be squeezed in between slower-to-sprout plants, such as carrots, in the vegetable garden. The radishes will be harvested before the other plants need the space. Plus, radishes are good for loosening and cultivating the soil. Just make sure no nearby plants will shade out your radishes.
Spacing, Depth, and Support
Sow seeds around 1/2 inch deep and 1 to 2 inches apart. Thin seedlings to 3 inches apart. Rows should be spaced three inches apart. A support structure won't be necessary.
Radish Plant Care
Radish plants need full sun, meaning at least six hours of direct sunlight on most days. Radishes grown in too much shade will put energy into leaf growth rather than root growth.
Radishes do best in rich, loamy or sandy, well-draining soil with a slightly acidic to neutral soil pH. The soil must not be heavy or compacted, as the roots won't grow well in those conditions.
Radish plants typically need 1 inch of water per week. Soil that's too dry can cause the plant to bolt (go to seed) and ruin the taste of the radishes, making it pithy, and soil that's too wet can cause the roots to split and rot. A layer of mulch around the plants can help to maintain soil moisture.
Temperature and Humidity
Radishes like temperatures between 40 and 70 degrees Fahrenheit, with temperatures in the low 60s being best. Hot weather can cause the plants to bolt and decline in quality. They can get tough and woody or spongy with hollow centers. Also, once a radish bolts, the bulb stops forming. Humidity typically isn't an issue as long as adequate soil moisture is maintained and there's good air flow around the plants.
If you’re already starting with rich soil, you typically won’t need to fertilize radishes. If you need to improve your soil, work in a few inches of compost prior to planting.
Bees and other pollinators will pollinate radish plants. And radish varieties will cross-pollinate with one another.
Types of Radishes
There are many radish varieties that differ based on their appearance and when they can be grown. They include:
- 'Cherry Belle': This is an early spring variety that's red and round. It matures in around 22 days.
- 'French Breakfast': This is a heat-tolerant variety that's oblong with a red and white color. It matures in around 23 days.
- 'Daikon': This variety grows well in cool climates, maturing in around 60 days. It's long and white and has a mild flavor.
Radishes vs. Turnips
As root vegetables, radishes and turnips have a similar look to them. But there are some notable differences. For one, radishes are generally smaller than turnips.
Take note of when your radish variety should be ready for harvesting. In general, harvest when the roots are around 1 inch in diameter. You can often see the shoulders of the radish rising slightly above the soil line. You might have to pull one out to see whether it’s ready. Don’t wait too long to harvest to ensure a pleasant flavor and tender texture.
To harvest, pull up the plants, and cut off both the tops and the thin roots. Leaving the leaves on will draw moisture and nutrients from the radish bulb. The greens can be stored in the refrigerator for a few days and can be eaten fresh or cooked. The bulbs can be stored in the refrigerator's vegetable crisper for one to two weeks. They also are good fresh or cooked in salads, soups, and more.
How to Grow Radishes in Pots
Container growing is a good option if you don’t have garden space or the loose soil that radishes need. Common radish roots are shallow, so they don’t require that deep of a pot. But it’s best to grow a round variety, rather than a long one, to make sure it has enough room to develop. A container that’s around 8 to 12 inches wide and deep should be fine. It also should have ample drainage holes. Unglazed clay containers are beneficial because they’ll allow excess soil moisture to evaporate through their walls, helping to prevent root rot. Use any high quality potting soil. Containers dry out more quickly and need more watering than in-ground gardens. Monitor moisture closely.
You won’t have to do any pruning on your radish plants beyond thinning seedlings. If the radishes remain crowded, they won’t develop properly. Fortunately, you can eat the seedlings you thin. Snip them off at ground level rather than pulling up their roots to avoid disturbing the roots of neighboring plants.
Radishes are typically grown from seed. And it’s possible to collect seeds from mature plants for future growth. You just have to make sure the plants haven’t cross-pollinated with any nearby relatives. Here’s how to save the seeds:
- Rather than pulling the radishes as they mature, allow the plant to remain in the ground. Eventually it will send up a flower stalk and produce seed pods.
- Remove mature seed pods once they’ve turned brown and dried out. Crush the pods to release the seeds. Separate the seeds from the rest of the pods.
- Place the seeds in a paper envelope, and store them in a cool, dry spot. They should remain viable for five years.
How to Grow Larger Radish Varieties From Seed
Sow seeds of large radish varieties slightly deeper than the small varieties. Gently firm the soil around the seeds, and keep it evenly moist but not soggy. Germination should occur in around three to 10 days. Make sure to remove any weeds around your seedlings to prevent competition for moisture and nutrients.
Radishes are annuals, meaning they complete their life cycle in one growing season. So no overwintering will be necessary.
Common Pests and Plant Diseases
Cabbage maggots are common pests for radish plants, as they will tunnel into the radishes. Cutworms also feed on radishes. And flea beetles will feed on radish leaves, but they won't injure the bulbs. Monitor to catch these insects before they destroy the whole crop. Growing your radishes under floating row covers can help to prevent pest issues. Wood ash mixed into soil can help deter root maggot. Some diseases that can affect radish plants include downy mildew, black root, and scab. But maintaining proper growing conditions can prevent many problems with diseases.
Are radishes easy to grow?
Radishes are easy vegetables to grow as long as they have well-draining soil and mild temperatures.
How long does it take to grow radishes?
Radish varieties take an average of 20 to 60 days to be ready for harvesting.
Do radishes come back every year?
Radishes are annuals, completing their life cycle in one growing season.