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Radishes not Growing Bulbs and Other Problems Growing Radishes

Do you have a problem with radishes not growing bulbs? This is a common issue in a vegetable garden. What causes this to happen?

Radishes – raphanus sativus – have edible greens which can be used in salads, but the main reason they are grown is for their crunchy and spicy round root. Expecting to pull out these roots only to discover that you have just a handful of greens and long and thin radishes is a big disappointment.

The good news is that radishes grow very quickly, – often in just 20 days – so once you know the reason for radishes not bulbing, you have lots of time to try again with a new crop.

Keep reading to learn the reasons radishes don’t develop as well as how to fix other radish growing problems.

Plants with long and thin radishes

Why are my radishes not growing bulbs?

This can happen for several reasons and some of the causes are easily fixed. In fact, many of the reasons are self inflicted by not avoiding the common vegetable gardening mistake of not thinning seedlings!

Sowing radish seeds too thickly and soil problems

Radish seeds are tiny and it is easy to sow them much too closely together. This makes it hard for the radishes to form bulbs.

Radishes need plenty of room for their roots to develop into those desirable round shapes. Without this room, they either won’t develop or will form long and thin shapes.

To sow radish seeds properly, plant them 1/4 to 1/2 inches deep in very loose soil and take care not to crowd the seeds. If the soil is too compacted, the bulbs will have problems forming.

Crop of densely planted radishes.

If you grow radishes in areas with lots of rainfall in the spring, the soil may get heavy and waterlogged which can make the plant stop producing bulbs.

Also take care not to add too much nitrogen to the soil, since this will promote leafy tops instead of bulbs.

Soil pH can be another reason for a lack of bulbs. Radishes like a soil pH of 6.0 to 7.0. Too alkaline a soil may result in no bulbs forming.

Radishes not thinned properly

Even if you take care when planting the radishes, you may find that they are still growing very closely together once they start maturing. This is where thinning radishes comes into play.

Once the tops have started growing, thin the seedlings so that there is 1 inch between each plant (even more if your varietal has very large bulbs.)

Radishes that are not thinned properly will rub against each other in the soil as they try to grow. This causes the problem of bulbs not forming.

Woman thinning radish seedlings.

Thin out radish plants when their first true leaves form. To limit any damage to the roots, thin the plant by snipping off the top at soil level. Never try to thin them by pulling the plant out.

Seedlings planted close together can have roots growing together too. If you pull out a nearby plant, you may damage the taproot of the seedlings you want to keep.

H0t weather can cause radishes to bolt and not form bulbs

Radishes are a cool-weather crop that like full sun to just partial shade. This means growing them in early spring or later in the fall.

Radishes in the sun on a white plate.

They grow best when the temperatures are generally between the 50 and 65° F range. Check the directions on your package. Some types of radishes are more heat tolerant that others.

If you try to grow radishes in hot weather, the plant will bolt and try to set seed instead of forming bulbs.

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Other problems growing radishes

The lack of bulbs forming is not the only radish problems that you may encounter when growing this popular vegetable. Spit or cracked bulbs, extra spicy or woody radishes are also things that may happen.

What causes cracked radishes?

The perfect radish is round and plump. What causes radishes to split? The cause is usually a problem with watering. Radishes like consistent moisture – about an inch of water each week is ideal.

Cracked radishes.

Leaving them without water for a week and then adding a lot at one time can cause the root to grow too quickly and split open.

While cracked radishes may not look too appetizing, they are still fine to eat. Slice them and no one will even notice that they were once split!

Why are my radishes too spicy?

Those who love radishes appreciate their spicy root, but no one wants to bite into one that is overly-spicy.

Red globe radishes, those most frequently grown, should have a medium spice level. If yours is too spicy for your taste, it has likely been growing too long and is too old.

Some vegetables, such as beets and carrots get more sweet, the longer they grow in the ground. Radishes are the opposite. If you leave them growing too long, the radish will simply get more spicy. 

What makes radishes become too woody and hard?

The reason for woody radishes is the same as for extra hot radishes – time growing in the garden!

Radish bulbs will become too woody if they are left in the ground for more than 30 to 50 days after sowing the seeds. Many radishes form perfectly in just 20 days, so harvesting soon and often is the key to tender and crisp radishes.

Old woody radishes on a plate.

If the reason for leaving the radishes growing longer is that you have more than you need, try succession planting every few weeks. That way you will always have some ready.

Even though there are several problems that you may encounter when growing radishes, they are worth the effort. By following proper planting and taking care of thinning, watering and soil needs, you can expect to enjoy a salad with your favorite radishes in about three weeks!

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Would you like a reminder of this post for why radishes don’t bulb? Just pin this image to one of your gardening boards on Pinterest so that you can easily find it later.

Unformed radishes on a white counter with words Why are my radishes not forming bulbs?

You can also watch our video for vegetable garden problems and solutions on YouTube

Yield: Bulb forming

How to Thin Radishes

Woman thinning radish seedlings.

If you sow radish seeds too densely and don' thin the plants, they won't form bulbs. Follow these steps to thin radishes properly

Active Time 20 minutes
Total Time 20 minutes
Difficulty easy


  • Radish Seeds
  • Watering can or hose


  • Small scissors


  1. Plant radish seeds according to package directions. Normally 1/4 to 1/2 inch deep.
  2. Be sure the soil is tilled well and drains easily.
  3. Choose a spot with 6 hours of direct sun. Sow in spring or fall. Hot weather prevents radish bulbs from forming.
  4. Water well.
  5. When the first set of true leaves appear, thin the plants.
  6. Use the small scissors to trim the leaves at soil level. (You can also pinch them with your fingertips.) Don't pull seedling out, since this can damage the roots you wish to keep.
  7. Thin plants so there is one inch between them. (More for larger varietals.)
  8. Enjoy your perfectly formed radishes in about 20 days.

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