Radishes are one of the easiest, fastest-growing vegetables you can grow, with some varieties claiming maturity in less than a month. They also grow extremely well in containers. Because of this, they’re always the first root vegetable I recommend growing.
Although radishes are easy to grow, they are also quite sensitive to growing conditions, so a lot of people have issues when growing them. Getting too big isn’t the problem; the problem is letting your radishes start bolting (producing a flower stalk) which will make your radishes immediately start turning woody, regardless of size.
How Long Does It Take to Grow Radishes?
Radishes are one of the fastest-growing crops to maturity. Radishes typically mature in 30-45 days. Some larger varieties, like daikon radishes, can take up to 50-60 days. And there are some varieties, like the French Breakfast radish, Cherriette, Celesta, and Pink Beauty which all can mature in under 30 days.
But, what you will notice is that when you plant your radishes in the spring or late fall, they will typically take longer than the days-to-maturity to grow because there are fewer daylight hours and cooler temperatures in those seasons. But these are the best times to grow radishes in most climates, unless you have cool summers.
So, those French Breakfast radishes that take 25-30 days might actually take 35 or 40 days in the fall, for example. However, you can basically pick radishes at any time, so you can start picking baby radishes once they start putting on some size. Radishes often start poking through the soil as their tuber grows, so you can get an idea of how large they are before pulling them.
What Happens If I Don’t Pick My Radishes?
Let’s say you decide to plant radishes and not harvest them. When it starts to bolt, you’ll see a stalk forming with smaller leaves along it. At this point, your radishes will start getting more fibrous. Typically, the tough fibers start forming near the outside of the radish. They are still perfectly edible, but if you pop one of those radishes into your mouth, although it will taste and feel just like a radish as you’re chewing, eventually you will be left chewing a wad of indigestible fiber. If your radishes are like this, I suggest cutting them horizontally into thin slices, which cuts up those tough fibers.
If you keep letting your radishes bolt, they will produce buds and flowers. By now, your radishes will be getting tougher and woodier, but they will still keep growing. After those radish flowers are pollinated, they will form big seed pods (the seeds are tiny, but the pods are fat). Radish seed pods are actually edible when they’re young, and taste just like radishes.
All radishes will eventually bolt, but hot and dry conditions cause radishes to bolt very easily. Just this year, we had a mini heatwave near the end of May. It was like July weather for a few days. Within a week, almost all my radishes had started bolting. Some of them were tiny but they were bolting and already starting to get woody. Once they start bolting, I always pull them out unless I’m saving the seeds or don’t mind waiting to get some radish seed pods first.
Finally, one thing you will notice is that radishes left to mature under hot temperatures will also be noticeably spicier. If you don’t like spicy radishes, planting in the fall is the way to go.
When to Harvest Radishes
You can harvest radishes any time before bolting, but typically, they’re picked when around 1 inch (2.5 cm) across. It also depends on the variety and how long they typically take to grow. French Breakfast radishes, my favorite, can be picked at 1/2 inch to 3/4 inch across. I also pick a few baby ones early in the season.
By the way, the leaves are also edible. When they’re mature, the leaves do tend to be bitter and a bit hairy, but they’re deliciously mild when small. If you’re growing a lot of radishes, feel free to pick a leaf or two off some of them and throw those leaves into a salad or sauté them.
How Do I Grow Big Radishes?
The best way to grow big radishes that aren’t woody is to grow large varieties. Cherriettes and French Breakfast radishes will rarely grow more than an inch wide. Meanwhile, the Giant of Sicily radish and China Rose radish can easily grow to a whopping 2 inches across, sometimes more.
If you want to maximize the size of your radishes, the key is to delay bolting as long as possible. The best way to achieve this is by growing radishes in the fall and (if your winters are mild) winter. Fall radishes are growing and maturing in increasingly cooler temperatures, so there is less risk of them prematurely bolting. It also means they are growing more slowly, which gives the root enough time to fully grow and develop.
It might be a golden rule that cool weather crops grow larger in the fall. My fall radishes, kohlrabi, and beets are always larger than the ones I grow in the spring.
Preventing Bolting in Spring/Summer Radishes
Okay, so I’ve definitely waxed lyrical about growing radishes in the fall. But what if you’re growing them in the spring and it’s starting to warm up a bit too much? Or maybe you’ve already planted them in the summer and want to avoid all your radishes bolting?
You have a few options. One is to invest in a shade cloth. Shade cloth is a black mesh which is designed to block a certain percentage of sunlight, which will give your vegetables some relief from the heat. You can drape the shade cloth over your radishes or, even better, keep it up with some stakes or PVC hoops. If you’re growing radishes in containers, you can also move them out of the sun during periods of extreme heat, or you can plant your radishes in partial shade.