Radishes are popular root vegetables belonging to the cabbage family. And you don’t need to love radishes to justify planting some in your veggie patch.
Radishes are incredibly easy to grow and reach maturity in a matter of weeks.
Most gardeners plant just 1 radish seed per hole. But how many radish seeds per hole you plant ultimately comes down to the seeds’ age and overall quality.
While radishes are typically grown for their flavorful roots, every part of the plant is edible. Another surprising benefit of planting radishes is that they can protect your other vegetables from nasty insects!
Tips For Starting Radishes From Seed
Radishes aren’t very picky about where they’re planted! However, you’ll need to make sure your chosen location receives at least 6 hours of sun per day.
Radishes grown in shade divert energy to produce bigger and taller leaves in an effort to get adequate sunlight. Unfortunately, bigger leaves equal a smaller root. That’s bad news for gardeners looking forward to a bountiful harvest!
And you can’t just look at the amount of sun your garden receives at the time of planting. Be sure to take into account the vegetables around your radishes and how they might block the sunlight as they grow!
You can plant radishes in spring and fall!
According to the Old Farmer’s Almanac, the best time to sow radishes is 4 to 6 weeks before either your area’s last frost date (in spring) or first frost date (in fall).
The general rule of thumb is that radishes can be grown as long as the temperature is below 70°F. Higher temperatures cause bolting or premature flowering.
Bolted radishes are extremely bitter and tough. While technically still edible, most people surrender radishes that have already flowered to the compost heap.
Radishes will grow in any loose, moderately rich soil.
Before sowing your radish seeds, it’s recommended to loosen the top few inches of soil by tilling. This will make it easier for your radishes to produce large, healthy roots.
Aged compost is a wonderful option for supplementing the soil prior to planting radishes. Add a small amount of compost to your vegetable garden to loosen heavy soil and replenish nutrients.
Radishes can be sown directly into the garden.
Plant seeds ½-inch deep, leaving about 1 inch between each hole. Space rows 12 inches apart.
Fresh radish seeds have a high germination rate, so many gardeners opt to plant just 1 seed per hole. If your seeds are a few years old or you want to guarantee a full garden bed, then you should place 2 radish seeds per hole.
Since radishes mature extremely fast, you might want to sow seeds several times to extend the harvest! You can plant new seeds every 10 days as long as the temperature stays in the correct range.
Many gardeners consider this step to be the most important in growing radishes from seed. Don’t skip it!
Failing to thin out radishes will result in overcrowded roots that may be extremely small or even inedible at maturity.
Once your radish seeds germinate and emerge as sprouts, you need to thin the seedlings to a spacing of 2 inches apart. This is best done when the seedlings are approximately 2 inches tall.
You don’t need to dig out the entire seedling — just pinch the stem at its base. Radish seedlings are 100% edible, and can be saved for use in salads and more!
Transplanting Radish Seedlings
Many vegetables can be started as seeds indoors before being transplanted into the garden. However, radishes don’t respond well to this practice.
Transplanting seedlings almost always lead to root damage. For radishes, that damage can affect the root tissue all the way up to harvest.
Some gardeners see good results by starting radish seeds in compostable pots made of peat. Peat pots can be buried directly into the ground, protecting the roots from transplant damage.
If you’re struggling to direct sow radishes in your climate, then these containers offer a way to transplant seedlings without needing to touch the roots.
How Long Do Radish Seeds Last?
Radish seeds can remain viable for 5 years or longer! The older the seeds get, however, the more you’ll want to plant to ensure a good germination rate.
Are Radish Seeds True To Type?
Seeds being “true to type” means that they will produce new plants that are of the same variety as the parent plants.
Radish seeds readily cross-pollinate. Unless you grow just one variety in your garden, you should expect some collected seeds to produce hybrids of the parent plants.
Cross-pollinated radishes may be more or less appetizing than their parent plants. But the only way to find out is to plant them in the garden next year!
Are Radish Seeds Edible?
Every part of a radish is edible, including the seeds!
If you find yourself with more seeds than you could possibly plant, consider using the excess to add texture to salads or as a quick snack.
How To Collect Your Own Radish Seeds
Once you’ve grown radishes in your garden for a single season, you can begin collecting seeds for future years! All you need to do is let some of your radishes flowers and then go to seed.
Radishes produce seed pods. The best strategy is to leave these pods on the plants to dry out.
Radish seed pods are prone to mold. Withhold water from that part of your garden and consider protecting your radish plants from the rain.
As the seed pods near maturity, you can cut the entire top of the radish and place it in a bag. Hang the covered foliage and seed pods upside down.
When the seeds are ready, the pods will naturally pop open! (The bag ensures none of your collected seeds fall to the ground when this happens.)
Alternatively, you can harvest the seed pods and let them mature somewhere cool and dry. When the pods start to break open, simply separate the seeds by hand.
Which Vegetables Can You Plant With Radish Seeds?
Radishes make wonderful companion plants. Their short season and ability to deter pests make them an awesome addition to any veggie patch.
The most important thing to consider when companion planting radishes is access to sunlight.
A great strategy is to plant radishes with slow-growing varieties of tomatoes or peppers. The radishes will be harvested before the other plants grow tall enough to block the sun!
Planting radishes near squash plants can protect the latter from cucumber beetles. The beetles are attracted to the radish foliage (the radish root is unaffected).
Meanwhile, growing radishes alongside other brassica plants — e.g., cabbage, broccoli, cauliflower, etc. — isn’t recommended. Radishes attract flea beetles which can spread to nearby brassicas.
How Many Radish Seeds Per Hole – Final Thoughts
Whether you’re an experienced gardener or are starting your very first veggie patch, radishes are practically a must-grow!
Sowing radish seeds directly into the soil is the best method. You only need 1 seed per hole in most cases to produce a bountiful crop.
Even if radishes aren’t your favorite thing to at, they’re still worth growing to keep harmful pests away from your other vegetables!