Radish Growth Stages

Radishes served with salt and butter are a summer delicacy. (Personal recommendation: try them with some fresh burrata cheese!) While you could source your radishes from the grocer or a local farmer’s market, they’re practically just as easy to grow at home.

Typically planted in the spring or fall, red summer radishes (Raphanus sativus) mature in as little as one month. Their close relative, the daikon radish (Raphanus sativus var. longipinnatus) takes a bit longer to grow under normal conditions and is frequently grown in winter.

In this article, I’ll walk you through the radish growth stages — from seed to harvest — and share some tips and tricks for your veggie garden.

Conditions for Growing Radish

Radishes come in numerous varieties, colors, and sizes. Though this article focuses on our classic red radish, you can generalize most of the following information to include all the radishes in your garden.

Radishes are annual vegetables that complete a full life cycle in just a single year (actually, it only takes a couple of months). They enjoy relatively cool weather that’s between 50 to 75°F. For this reason, radishes are most commonly planted in the spring, late summer, or fall.

Plant radishes in full sun for the best results. Like all root vegetables, radishes need loose, rich soil to develop. Soil that is extremely compacted or contains large pieces of debris can produce deformed radishes.

You can grow small radishes in containers or raised beds with little trouble. Standard red radishes need soil at least 6 inches deep to form properly. Remember that larger varieties, such as daikon radishes, may need up to 24 inches of loose soil.

Radish Growth Rate

Radish greens can grow 1 to 2 inches per week. The leaves of most varieties reach 6 to 8 inches tall by the time of harvest.

Red radish bulbs are usually harvested when they are 1 inch in diameter. Most of this size is put on in the final weeks of growth. 

Remember: Radishes are quite small vegetables, so even though they grow incredibly quickly, you might not see dramatic physical changes! 

Growth Stages of Radish

The radish is one of the fastest-maturing vegetables you can grow in your garden. Most radishes mature just 21 to 60 days after planting.

Larger radish varieties, such as the popular daikon radish, take longer to develop than traditional small, red radishes. Winter radishes, including daikon, often take about 50 to 8 days to fully mature.

1. Seed Germination

Radishes are grown from seeds. Some gardeners think that you need to plant a radish bulb to make a new plant, but this isn’t how the radish life cycle works.

Radish seeds will germinate in soil temperatures of 55 to 85°F. However, temperatures around 65 to 70°F are usually ideal for radish development.

On top of being extremely quick and easy to grow, radish seeds sprout at a very high rate. You can expect about 80% of your seeds to germinate and grow into sprouts or mature plants! Radish seeds remain viable in storage for about four years on average.

If you already understand the basics of plant germination, then there’s nothing really special about the radish that you need to learn. If not, here’s a quick breakdown of the germination process:

  1. The seed imbibes water from the soil through the seed coat.
  2. Cell division starts inside the seed embryo.
  3. The seed produces a primary root called a radicle.
  4. The seed produces a primary shoot and two embryonic leaves. These structures are called the hypocotyl and cotyledons.

Cornell University says that radish sprouts can emerge in the right growing conditions after 3 to 4 days. Next is the seedling or sprout stage!

2. Seedlings

Radish sprouts start with two unique leaves called cotyledons. These leaves are part of the seed embryo and act as a potent energy source for the seedling as it sprouts. All cabbage family members (including radishes) have cotyledons that look a lot like the capital letter ‘B’. 

Raddish Seedlings

Cotyledons differ from the rest of the foliage on any given plant. A radish sprout usually takes a few days to develop its first ‘true leaves’. These leaves will perform photosynthesis and be the same shape as mature radish foliage.

Though this is only the beginning of the radish life cycle, it’s common to harvest the sprouts after only 5 to 6 days of growth. You can use radish sprouts in the kitchen like any other young, tender vegetable sprout.

3. Vegetative Growth

Without first growing some leaves, you can’t grow a healthy, flavorful radish bulb. The radish top growth is responsible for creating the energy that gets stored in the plant’s bulb (which we later eat).

Most radishes eventually produce a dozen or more elongated, dark green leaves. Radish leaves vary in size but are usually between 6 and 8 inches long at maturity. The leaves are 100% edible and can be used alongside the rich bulbs in salads or other vegetable dishes.

4. Root Development

The radish root develops simultaneously with the leaves above the soil. Young radish sprouts have thick taproots about 3 to 6 inches long (according to the University of Illinois, daikon radishes can have roots up to 18 inches long!). Small, hair-like roots grow along the length of the taproot.

Throughout 3 to 6 weeks, the upper portion of the taproot will expand and (depending on the variety of radish) turn red. Some radishes have very round taproots, while others are much more elongated. Daikon radishes, for example, tend to expand down the entire length of the taproot.

5. Flowering

Radish flowers are small with white, pink, or purple petals. Like the leaves, the flowers are completely edible and can be used as an attractive garnish.

Raddish Flowering

Radishes are typically harvested before they have a chance to flower. However, a mistimed planting or unseasonably warm weather can trigger early flowering. This is called bolting.

Why are radish flowers generally seen as a bad thing? A radish that has begun to flower isn’t great for eating (at least if you want to harvest and eat the bulb). The plant uses the energy stored in the radish bulb to produce its flower stalk, so a flowering radish loses its flavor and has an unappetizing texture.

6. Seed Production

If you want your radish plants to produce seeds for a future crop, you first need the flowers to cross-pollinate. Most radishes have self-sterile flowers that won’t pollinate themselves, so more than one radish plant is needed to create seeds. Honey bees and other flying insects are the primary pollinators of radishes.

Different radish varieties readily cross-pollinate. Keep this in mind if you want to save seeds for future planting. I recommend one of two strategies: You can grow just one type of radish per season OR only let one variety in your garden go to flower. This will prevent accidental cross-pollination.

Radish seeds form in pods similar to beans or peas. It can take 14 to 28 days for tender green pods to develop after the radish bulbs are ready to harvest. (You can eat radish seed pods when they are still green!)

Raddish Seed Production

It may take a few more weeks for the radish seeds to fully mature and dry out. You want to wait for this stage if you plan to store the seeds to plant the following year. You can check whether or not the seeds are ready to collect by shaking the pods and listening for a rattling sound.

When to Harvest Radish

You can use many rules of thumb when harvesting radishes from your garden. For example, one common trick is to harvest the bulbs when the leaves are over 4 inches tall. My favorite method is to simply count the days since the radishes were planted and check the roots’ size after 21 to 30 days (or longer for some varieties).

The average red radish should be 1 inch in diameter at harvest time. Remember that different varieties may be smaller or larger, so I recommend referencing the original seed pack or nursery tag for the most accurate information.

Leaving radishes in the ground for too long can lead to cracked, dry, or tough bulbs. While you can still eat such radishes, properly developed radishes are far more enjoyable!

For more about growth cycles for members of the cabbage family, here’s a link to Cabbage Plant Growth Stages.

FAQs Radish Growth Stages

Can you eat radishes after they flower?

Radishes that have started to flower are still safe to eat but may not have the best taste or texture! Instead, try harvesting the seed pods. Pick pods when they are still green and the seeds inside have just begun to swell for the best flavor.

Citations

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Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.