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Radishes are a fun addition to any garden. They’re quick and easy to grow, and their spicy bite adds a tasty crunch to many dishes.
They’re a root vegetable, meaning the root is the part usually eaten. So when you harvest your radish you’re looking for that yummy root.
But what happens when you pull your radishes, and instead of finding a little round globe, you find a misshapen lump or no radish at all?
Why didn’t your radishes form?
There are five main reasons a radish doesn’t form a proper bulb.
- Your radishes are growing too close together.
- The soil is too compacted.
- You’ve used a fertilizer with too much nitrogen.
- Incorrect amounts of water or sunlight.
- You’ve planted your radishes at the wrong time.
Let’s take a look at each of these in more detail, so you can learn how to prevent future problems with your radish bulbs.
Why Your Radishes Aren’t Round
Radish greens are delicious and good for you.
But those green tops are not why you planted your radishes. You want to see those red, plump globes at the end of those greens.
And when you don’t, it leaves you scratching your head, wondering what happened.
Now, not all radishes are meant to grow into that iconic radish image. Different radish varieties have differently shaped bulbs.
But, regardless of the radish type, you want the bulb to form properly.
So, let’s look at the reasons why it may not form, and how to fix it, so poorly formed bulbs aren’t a future problem.
To learn more about growing radishes, take a look here at my how-to guide. You’ll find it helpful.
1. Your Radishes Are Growing Too Close Together
Radish seeds aren’t huge, so it’s easy to plant too many too close together.
However, overplanting is not the main problem. In fact, you want to plant extra seeds in each group or row because not every seed will germinate.
But, when you plant radishes thickly and fail to thin them out, then you have a problem.
If you don’t thin your radishes, they’ll end up crowding each other out and they won’t have enough room to form a proper bulb.
Solution:
When I plant radishes, I always sow extra seeds. But, I’m careful to thin them out as soon as possible.
And that’s the key
Radishes are quick growers and will break through the soil in no time. So it’s important you keep an eye out for those seedlings.
Once they appear, start your thinning process.
Radishes should be thinned to a minimum of an inch apart. Two inches is better. But always follow the package instructions. Larger radishes may need more growing space.
Keep checking your radishes throughout the growing season and don’t be afraid to thin vigorously. With young seedlings, it’s easy to miss a few radishes that are planted close together.
Pick the weakest looking seedling to remove.
Lastly, when harvesting, harvest every second radish so that the remaining radishes have more space to grow.
2. The Soil Is Too Compacted
As a root veggie, your radish needs to break through the soil in order to grow.
Having too compacted a soil can interfere with your radishes root being able to expand. Which can stunt your radish’s growth.
This can be especially problematic if you have a lot of clay in your soil.
Solution:
Before planting your radishes work your soil with a hoe or trowel. Aim for loosening the soil 8 – 10 inches down.
This will give your radishes plenty of room to grow and expand both downwards and outwards.
If you’re wondering what other tools you need for gardening, take a look at my article on the subject. You’ll find it helpful.
According to the University of Minnesota Extension Office, when planting your seeds, plant smaller varieties ¼ to ½ inch deep. Plant larger varieties up to an inch deep.
3. You’ve Added Too Much Nitrogen
Nitrogen is a macronutrient plants need. In particular, it helps the green part of plants – the leaves and stems – grow.
Normally, that’s a good thing. And it is with radishes – to an extent.
But giving a radish too much nitrogen encourages the green stalks above ground to grow, but not so much the bulbs below ground.
The result is you end up with thick, leafy tops but poorly looking bulbs.
Solution:
Because radishes are such fast growers, fertilizing is not necessary. Especially when planting spring radishes.
If you’re a new gardener, you might consider skipping the fertilizer altogether. This way, you won’t chance giving your radishes too much fertilizer, or the wrong type of fertilizer.
But, if you want to fertilize, then use a fertilizer with a lower nitrogen(N) level and a higher phosphorus (P) level. On a fertilizer label, nitrogen is the first number and phosphorus is the second number.
For example, 15-30-15 means there’s 15% nitrogen, 30% phosphorous, and 15% potassium in the fertilizer.
Radishes like slightly acidic soil. Working some peat moss into the soil can also help feed your plants.
4. Water and Sunlight
Radishes like water, but they won’t like sitting in too much water for too long a period of time.
If the soil becomes too wet, the bulbs can become waterlogged, which can stunt their growth.
Not only do radishes need proper amounts of water, but they also need sunlight. Without enough sunlight, they’ll have difficulty growing to maturity.
In general, radishes need at least six hours of sunlight per day.
Solution:
When choosing your radish spot, make sure the location has plenty of sunlight. In other words, don’t plant beneath a large tree or next to a building that’s going to shade your radishes for most of the day.
Also, don’t pick a spot at the bottom of sloping ground, where runoff from rain will sit and pool.
If you live in a zone that has a rainy season, plant your radishes when the weather is drier.
And lastly, if planting radishes in a container, make sure your container has good drainage holes.
5. Planting Radishes at the Wrong Time
Radishes are a cool weather crop, meaning they don’t like mid-summer heat.
If you plant your radishes too late in the season, the weather may warm too quickly for them.
And when this happens, your radishes can bolt. In other words, they’ll go to seed before they’re ready to harvest.
Solution:
Because radishes are cool weather plants, if planted too late in the season they can go to seed, become woody and unpleasant tasting, or not grow at all.
In general, aim for a spring or fall planting, rather than planting in the middle of the summer.
How far into the season you can plant, will depend on your area. I’ve written an article on when it’s too late for radishes. You can check it out here.
But, it’s not only the timing of your planting that matters. You also need to keep an eye out for upcoming weather. Especially if you live in a hotter zone.
If it’s calling for a heat wave, then hold off on planting your radishes. Even if that means waiting until the fall.
Can My Current Radish Crop Be Saved?
Whether or not a current crop of radishes can be saved, is dependent on why your radishes failed in the first place.
If you’ve planted your radishes too closely together and haven’t been thinning them, they may still be salvageable. Your success depends on how close they are to their harvest time.
Radishes that have bolted, become waterlogged, or are not growing because of overfertilization or lack of sunlight, are likely not fixable.
In these cases, you are better off starting a new batch.
The good news is radishes grow quickly. Spring radishes need about 20 – 30 days.
So as long as there is still time before temperatures get too hot, you should be able to plant a second crop.
And, if follow the recommendations above, your new batch should do well.
If it’s too late for a spring planting, then think about planting in the fall.
Final Thoughts
- The main causes of radishes not bulbing properly are,
- They haven’t been thinned.
- The soil is too complicated.
- They’ve received too much nitrogen.
- They’re getting too much water or too little sunlight.
- They’ve been planted at the wrong time.
- There are solutions to these problems.
- If current crops cannot be saved, planting a second batch is a good option since radishes grow quickly.
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