How Can You Tell When Radishes Are Ready?

I like my radishes a little bit spicy and 100% crisp. The problem is, since they’re growing underground, how can you tell when they’ve grown to perfection? 

My first couple of seasons growing radishes, I was nervous if anything was happening under the surface at all. My plants produced lots of lush green leaves above ground, but when I harvested them, I was disappointed by the taproot size. Over the years, I’ve learned three signs to look for to harvest perfect, salad-ready radishes. 

You're within the window of the time guideline on your radish seed packet

I know, this one seems obvious, but how many of us have tried to assemble a piece of furniture without reading the directions?

I may ignore the spacing suggestions on the backs of those little seed packs, but I’ve found that their time-to-harvest estimates are usually pretty accurate, plus or minus 10 days or so, especially when the weather has been optimal.  

Let's say you're planting your first round of French breakfast radishes in early March. You'll come out about seven to ten days later to thin radish seedlings to give your top plants adequate space to grow their taproots. You'll return in early April, or after about 30 days from planting (as the packet most likely recommends), to check on their growth.

Different types of radishes have different grow times, so be sure to check your packet. 

The radish greens above the soil have grown to be 6 to 8 inches tall

It’s true for most plants that the root growth and the shoot growth imitate one another when it comes to pacing. As above, so below, so to speak.

If you don't see a lot of green growth above the soil line, then there’s probably not much happening to your little radish root below either. On the other hand, if one shoot has grown significantly taller than its neighbors, the radish attached to it will probably be just a little too big. 

For French breakfast radishes, look for greens that are about six to eight inches tall. 

The radish passes the shoulder test

The shoulder of a radish is the part that pushes up against the topsoil, the part that breaks through when you give the shoots overhead a good tug.

Use your finger to sweep around the base of the greens a bit to see if you can feel the shoulders. If you don’t feel anything, the radish probably needs more time to develop, so just push the soil back in place to give the teenage radish more privacy. 

Sometimes, the radishes show you they’re ready to harvest by popping their shoulders above ground to say hi. They’re not likely to continue growing much once they’re bursting out of the ground, so that makes the decision to pull or not to pull really easy! 

What happens if you leave a radish in the soil too long?

When radishes are near their time to harvest, it’s really important to watch them. If you harvest them too late, they can become starchy. I wanted to grow huge radishes for a photoshoot one year; they may have looked camera-ready, but they ended up tasting awful.

Here's how to salvage your radishes if you leave them in the soil too long. 

What can you plant after you've harvested your radishes?

Once you pull up your first batch of perfect radishes, you might be wondering what to do with that empty space in your garden. After all, the last thing you want to do is leave soil bare, right?

If you know that you're still going to have the right temperature for radishes (between 35 and 65 degrees Fahrenheit) for at least 30 more days, you can always plant a second round. Just add a handful of compost and sow more radish seeds in the areas you've just harvested your first round from. That way, you can keep enjoying radishes through the rest of your cool growing season! 

If, however, you expect the weather to change soon, you can plant something else in that spot to prepare for the upcoming warm growing season. I recommend going with something from a different family, so you could, for example, grow bush beans to hang over the side of your raised garden bed, or you could add some basil as soon as you're frost-free. 

To me, that’s the beauty of a kitchen garden: you can keep coming back and planting more, growing more, so that there's always something to harvest.

Enjoy your perfect homegrown radishes!

I hope this guide has you harvesting crisp radishes of all different shapes and sizes in no time! 

For more tips on growing perfect French breakfast radishes, read my full growing suggestions. If you'd like to save your own radish seeds for next season, here's how to harvest and store seeds. 

Don’t forget: you can also eat the radish greens. That means radishes are double your money!

Happy growing, my friends.