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Like tomatoes, radishes are a vegetable you have to grow yourself in order to enjoy their true flavor and knowing when to harvest radish is the key to that enjoyment. Grocery store radishes often taste quite spicy, but radishes grown in your garden and harvested at the correct time have a mild flavor and add a crisp crunch to salads and sandwiches. Members of the cabbage family (Brassicaceae), like broccoli and kale, these delicious globes of white flesh are also fun to grow. Here’s how to know when to pick radishes for peak flavor.
Why is knowing when to harvest radish important?
Unlike some other crops which can be harvested on a rolling basis as they ripen (green beans, peppers, and cucumbers, I’m talking about you!), radishes are a “once and done” crop. Each radish seed yields one radish root. If you miss the correct planting or harvesting time for radishes, your yield will be a whole lot of leaves and no delicious roots or over-ripe roots that are cracked, woody, and bitter. If you’ve tried growing radish before only for the plants to never develop their classic scarlet globe roots, you know the exact disappointment I’m talking about.
No matter which radish varieties you grow, success is all about the right timing. And I’m referring to both the timing of the planting and the timing of the harvest.
Radish is a cool weather-loving crop. If you wait too long to plant radish seeds, the weather and soil will be too warm, and no roots will form. The leaves may be large and robust, but the root will look more like a rat tail root than a radish. Peak planting times are very early spring for late spring harvests and late summer for fall harvests.
When the planting is properly timed, figuring out when to harvest radish isn’t difficult, and there are several methods you can use to determine when the roots are ready to be pulled.
When to harvest radish based on the planting date
Since radish seeds are most often planted in the very early spring, 4-6 weeks before your last spring frost, they are among the earliest spring harvests for most gardeners. In my Pennsylvania garden, our last expected spring frost date is May 15th, so I sow seeds into the garden straight out of the seed packet starting around the end of March. Then I continue to sow more radish seeds every week through April and until the end of May when the weather really starts to warm. Making multiple sowings like this keeps my family in radishes for weeks instead of days, and it keeps us from being overwhelmed with too many radishes all at once.
One of the easiest ways to know when to harvest radish is to keep track of your planting dates. Most radish varieties are ready to be pulled 30 to 45 days after sowing the seeds. If you remember when you planted the seeds, it’s easy to determine the best harvesting date. Ripe radishes will only hold in the soil for a week or two past their peak. If you keep them in the ground too long, the roots taste bitter and the texture is woody. Plus, the plants will go to flower (which is great for the pollinators but not so good for the salad plate).
As mentioned earlier, late summer plantings can also be made for fall harvest. I start sowing more radish seeds in late August through September. They’re ready to pick 30-45 days after sowing.
When to harvest radish by their size
Another great way to know when to harvest radish is by the diameter of their roots. Typically, the “shoulders” of the roots stick out above the surface of the soil. This is totally normal and even serves as a good indicator of the maturity of your radish plants.
When they are seedlings, the top of the root gradually starts to color up and thicken. For classic round radish varieties, like Cherry Belle and Easter Egg, when the root’s diameter reaches about 1-inch across, they are ready for harvest. For oblong varieties, like White Icicle and French Breakfast (my favorite!), their root girth at maturity isn’t as thick since the roots are longer than they are wide. For these varieties, I harvest when the shoulder of the root is the same diameter as my thumb. Here again, don’t wait too long to harvest or the roots will split or become woody.
When to harvest radish based on the variety
Using the root size as a harvest indicator goes hand in hand with using the variety type as a harvest indicator since the variety determines the eventual size of the root. Generally speaking, a spring variety has thinner skin and won’t hold in the ground as long, while fall-planted winter radishes have thicker skins and can stay in the garden until the ground freezes even if they are fully mature. Some varieties are even bred specifically for fall and winter growing. Most that are, have a slightly longer maturation period; more like 50 to 60 days. China Rose and Watermelon radish are two wonderful winter varieties that are great for fall planting and late-season harvests. Many Daikon radish types can even be planted throughout the summer for fall and winter harvest.
What to do if your radish roots don’t form
If your radish plants don’t form roots at all, there could be a few different factors at play.
- You may have planted them too late. Remember, earlier is better than later. Aim for cold weather and soil that is cold but no longer frozen.
- Even moisture is another key to success with radishes. If the soil dries out when the plants are just seedlings, the water stress will result in minimal “bulbing” of the roots.
- You planted too closely. Radish roots need room to grow and fully form. Sow the seeds ½ to 1 inch apart. Or thin them to that spacing when they are small seedlings.
- Do not feed radish fertilizers that are high in nitrogen. Nitrogen makes big leaves, not big roots. Use a balanced organic fertilizer or one that’s slightly higher in phosphorous (the middle number on the label) for the best results.
- Mulch your radish plants to help stabilize soil temperatures and cut down on competition from weeds. Use shredded leaves, straw, or finished compost.
- Test your soil pH every 3 to 4 years to be sure it falls in the optimum range for radish growth. 6.5 is an ideal target pH as that’s when the most nutrients are available to fuel plant growth. A pH that’s too high or too low can bind certain nutrients into the soil so plants can’t access them. (Learn more about managing soil pH here).
How to harvest radish roots
Aside from knowing when to harvest radish, it’s important to know how to harvest them. Round radishes are incredibly easy to harvest. They are shallow-rooted and a simple tug on the leaves is enough to uproot them. Oblong, oval, or deep-rooted radish types, like daikons, are a little more challenging. Use a trowel or garden fork to gently pry them out of the soil. Some of them can grow quite deep, so you’ll need to dig carefully.
More tips for growing radish
- After harvesting, cut off the leaves and wash the roots under cool running water. Pack the roots into plastic bags and put them in the crisper drawer of the refrigerator. I put a slightly moist paper towel in the bottom of each bag to keep the roots from drying out. When stored this way, they’ll keep for 4 to 6 weeks.
- The main insect pests of radishes are flea beetles, aphids, and cabbageworms. Flea beetles cause small irregular holes in the leaves which are more aesthetic than damaging. I ignore them. I also ignore aphids. Within a few days of them showing up, the ladybugs, lacewings, and other aphid predators arrive and take care of the problem for me. If cabbageworms become problematic, here are some tips for managing cabbageworms organically.
- If your radish go to flower because the weather grows too hot before you can harvest, all is not lost. The seed pods that follow the flowers are edible and taste just like the roots. Pick them when they begin to swell.
I hope you’ll enjoy cultivating your own homegrown roots with these tips on when to harvest radish and the accompanying info on how to time the plantings. They’ll become a fast favorite for both their flavor and their ease of growth.
Here are more articles on when to harvest various crops:
- When to harvest beets
- Tips for picking spinach
- The best time to harvest peas
- When to pick broccoli heads
- Making the rhubarb harvest
- The best time to pick tomatillos
- Carrot harvesting tips
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