Radishes don’t like the heat. The only heat-resistant radishes are summer radishes, such as Rover, French Breakfast, Icicle, and Sora. These radishes can all withstand warmer temperatures, but even they will be adversely affected by hot, dry summer weather.
Radishes should be planted in full sun only if you’re planting in the spring or fall. In the dead of summer, they will want partial shade.
As for soil, they aren’t particularly picky, but like all root vegetables, they will soak up nutrients in garden beds, which is why it’s best to spread them out amongst plants rather than deplete a whole bed with a crop too big to use.
Also, like root crops, rocky soil isn’t ideal for radishes. When you see carrots with legs and radishes with flat bottoms, it’s because they’re trying to navigate rocky soil.
Instead, radishes will grow best in loamy soil that’s slightly acidic (about 6.5 pH) and rich with compost and nutrients. Radishes don’t like soil that stays soaking wet because they’re prone to root rot. Given that almost their entire being is root, you can lose your whole crop in poorly drained soil. Radishes do however like to be kept moist and not dry. This is true for both growing and after they have been harvested.
If you need to improve drainage, you can add sand before planting radishes, however, you may need to water more frequently.
If you need to change the pH of your soil, use hydrated lime to raise soil pH or use sulfur to lower it.
If you have questionable rockiness in your soil, dig down to a depth of about a foot (most radishes don’t grow to that length, but you’re giving the roots lots of clear growing space). If you have heavy soil, you can mix in some vermiculite to lighten things up. If you have really heavy, clay soil, consider planting in raised beds or containers instead.
Then, before planting, amend your soil with an inch or two of compost, and test your soil to make sure it has that ideal pH of about 6.5.
How do you grow your radishes? Have you had your soil tested or do you do it yourself? Please tell us your tips and tricks for growing great radishes!