Radishes are the fast food of the gardening world. That's not because of poor quality or health code violations, rather due to the fact that many varieties are ready to harvest in less than a month from planting. This is a welcome deviation from the typically delayed gratification that vegetables provide.
The quick growth of radishes makes them an excellent beginner vegetable for new gardeners. The experience of eating something you planted from seed is important to establish the confidence that will motivate you through the rest of the growing season. If you follow the principles outlined below, you could grab a packet of radish seeds tomorrow and be eating homegrown veggies before you know it.
Radishes come in many different shapes, colors, and sizes, but they are generally categorized as either spring radishes or winter radishes. Spring radishes are smaller and very fast growing. The classic red radishes sold in most American grocery stores are spring radishes.
Winter radishes are a bit of a misnomer because they also grow in the spring and summer, but they are stockier and store for longer periods of time so they can be eaten over the winter. Some popular varieties of winter radishes include Daikon and Spanish black. Keep in mind that winter radishes are slower growing than spring radishes and most varieties take about two months to mature, compared to one month for spring radishes.
Radishes can be seeded directly in your garden beds very early in the spring. A good rule of thumb is that you can plant as soon as the soil is warm enough to be workable (read: not frozen). Radishes germinate extremely quickly if conditions are right, and you can sometimes see your seedlings emerging within three or four days of sowing.
Planting individual radish seeds can be tedious work, so on our homestead we prefer to drag a stick through our garden beds where we want to plant the radishes and then sprinkle the seeds into the furrow. If they are seeded a little bit too heavily in certain places, you can thin them out when the first leaves emerge. Repeat this process every two weeks in the spring for a continuous harvest of fresh radishes.
As mentioned above, radishes are incredibly fast-growing even in cool spring weather. Because of their quick growth, they are excellent companion plants for slower-growing spring vegetables. We like to interplant our carrot and beet rows with rows of radishes to maximize the harvest from our limited space and prevent weeds from growing between the carrots and beets. The radishes will be ready to harvest long before they begin to compete with the other plants.
Like most garden vegetables, radishes prefer to grow in full sun (at least six hours per day). You can grow them in partial sun (three to six hours per day), but the yields will be lower. A rich compost-filled soil with consistent moisture will produce the highest quality radishes. If their access to water is inconsistent it can lead to the radish bulbs splitting and becoming pithy and dry inside. Radishes are triggered into their seed production phase by the long warm days of summer, so when your radishes start to make flowers, it’s probably best to harvest them and then wait until fall to start planting more successions.
The primary pests that will attack your radishes are flea beetles and small mammals. Flea beetles chew tiny holes in the leaves, which can stunt the plant’s growth when they first emerge, but healthy adult plants are generally not severely harmed by this pest. The main impact of flea beetles is to change the radishes' flavor. The subtle spiciness you taste when biting a radish is actually a defense compound the plant uses to ward off insect pests. When radishes are under attack, they ramp up production of these compounds and become spicier. If you like extra spicy radishes, you should actually welcome a few flea beetles to your radish patch!
Mammals like rabbits and groundhogs can be a major problem for basically any small vegetable. If they are present in your garden, take measures to prevent them from accessing your radishes and everything else nearby.
In my experience, radishes are pretty resistant to disease, probably because they grow so quickly that a lot of fungal and bacterial diseases don’t have time to impact them before harvest. If you do notice any fungal diseases in your radish patch, you should avoid planting brassicas in that garden bed for the next few years. A regular crop rotation schedule should help prevent this as well.
When your radishes begin to bulb out and swell up, they are ready to harvest at any point. The most commonly eaten parts of radishes are the bulbs, but all parts of the plant are edible. The leaves make a nice braising green that can be used in the same way as their mustard and turnip green cousins. If you let your radishes flower and go to seed, they will produce edible green seed pods that add a spicy crunch to salads. Just make sure to harvest the seed pods before they mature and dry out.