My favorite thing about growing radishes is that they provide almost instant gratification. They are the fastest plant in my garden to go from seed to salad bowl. The time between when I put the seeds in, to the time I pluck the radishes out, is only about 3 or 4 weeks!
Because radishes grow so fast they should be planted every 10 days or so throughout the spring, and then again from mid-to-late summer through fall. Like other cabbage family crops, when it gets hot in the middle of the summer, radishes will bolt, or send up a flower stalk. So grow them at both ends of the season.
Plant them about a ½ deep and 3” apart for ordinary radishes. I always plant two seeds per hole at their final spacing, and then thin by pinching off the smaller of the two seedlings. For spacings on the huge or specialty varieties, you’ll have to read the seed packet.
I learned the hard way not to plant too many radishes at once. How many radishes do you think you’ll eat in about 10 days? Only plant that many in the first planting, then about 10 days later plant that many again (further down the bed). Then again in ten more days, do the same thing one more time. In about a month, you can begin three sequential harvests of radishes. Then...
From there on out for the remainder of the spring, take a few seeds and a little recycled yogurt carton full of compost out to the garden every time you go out to harvest. After you pull out a few radishes, shake off the dirt, put a teeny bit of compost in the holes, and plant replacement seeds. This will help prevent using a bunch of garden space for tough old radishes that are going to seed because you just couldn’t eat them as fast as they matured.
You’ll be able to see where you last harvested and planted by the size of the plants. Get a nice big garden photography calendar to hang up and remind yourself when your different garden tasks (like sowing radishes) are due. This technique, with different timing, works for other crops too. I use it for other fast growers like spinach and even lettuce.
Radishes come in huge variety of sizes, colors and shapes, and it is fun in the winter to browse through the seed catalogs to find odd-shaped or fancy colored ones to try. I like to grow an old standby variety as well as try a new one each year just for fun.
Radishes are also a good soil-healer. Radish roots go much deeper than the knob that you pull out to eat - they can reach down 5 feet! When you harvest the radish those roots remain, and as they are eaten and decayed by soil fauna and microbes they provide channels for air and water to enter the soil, improving soil structure.
Radishes are in the cabbage family, and they like some of the same things that cabbages do, which means growing radishes in loose, fertile soil (translate: lots of compost) with a slightly acidic pH.
Most people don’t want to have to mess with their garden’s pH, and if that is you just know that plenty of compost will do wonders for moderating it if it is a bit too high or too low.
If plants in general in your garden fail to thrive, grow with funny colored leaves or are just stunted, I would recommend a soil test at your local state university extension service. Once you know what is out of whack, you can correct it using the appropriate organic fertilizer if necessary. Normal limits for soil pH are about 6.0 to 7.5. Radishes like it best somewhere below 7.
Radishes need to be harvested on a regular basis, when they are about as big as a cherry (although this depends on your variety). If you don’t pull them just before or at maturity, they will get tough and pithy and they may crack down the side.
If you have a small garden and are short on growing space, growing radishes between slower-growing crops like lettuce works well because radishes are so fast they can be harvested before the lettuce even realizes it has competition.
Nitrogen fertilizer or high-nitrogen compost tends to encourage leaf growth, a good thing if you’re growing cabbage, but not so much if you’re growing radishes. Even though they’re in the cabbage family, they are a root crop, so don’t give radishes as much nitrogen as leaf crops.
When the weather gets hot, radishes do too, so if you like ‘em hot like horseradish, let them grow into summer. (Unfortunately, though, they will also get tougher.)
The same bugs that bother cabbages also bother radishes: flea
beetles (especially when they’re little), cabbage root maggots, and leaf miner.
You can avoid all of these by growing radishes under a floating row cover like
Reemay or Agribon, which physically prevents access to the plants by the bugs.
If your radishes look like they’ve been chewed on the surface, it’s probably cabbage root maggots. Once they are in the soil, there’s not much you can do about it. Mice will also chew radishes, and they cause more damage.
So, have fun growing radishes! Come back and visit me often, for tips and advice on all aspects of vegetable gardening, learning how to compost, the latest tool reviews and more.
Blessings on your garden!