How Much Sun Do Radishes Need To Grow?

Radishes are a cool weather vegetable that is enjoyed around the world. The bracing, peppery taste of radish lends itself to all sorts of dishes, and there are further renowned for their detoxifying and cleansing properties.

planted white icicle radishes among carrots
planted white icicle radishes among carrots

Growing radishes is the perfect cool season addition to your garden, and are usually ready for harvest before the trees start showing leaves in the spring. But how much sun do our radishes need to grow?

Radishes do well with at least 6 hours of sunlight per day, but they are also quite tolerant of partial shade. So long as the weather and ground are cool, radishes will also thrive with extra sunlight.

Radishes are one vegetable where other requirements and soil conditions can easily take precedence over the amount of sunlight they are getting.

They don’t need a ton of it, and so long as you can keep the soil around them cool you could expect a good harvest with just 6 hours of sun a day.

Keep reading to learn everything else you need to know.

Do Radishes Need Full Sun?

Yes, but they are also tolerant of partial and even dappled shade.

How Many Hours of Sun Do Radishes Need?

Radishes will do great with about six hours of direct sunlight every day.

Can Radishes Grow in Shade?

Yes, and grow surprisingly well. Radishes love staying cool, and if the stay in the shade for much of the day they will often last a little longer into the season as it warms up since the soil stays cooler.

Don’t be afraid to plant radishes in areas that get some dappled shade throughout the day.

Can Radishes Get Too Much Sun?

Yes. If they are in direct sunlight for too long during the day, especially if it’s very hot out, the roots can get sunburned if exposed.

The tops of the radishes may also start to bolt (flower and go to seed) if they are getting too much sun.

Bolting is a process that occurs when a plant is stressed due to any number of reasons, and in the case of radishes usually excessive sun and warmth.

Concerned for its continued existence, the radish will put all of its energy into flowering and making seeds instead of growing a large root.

This is in an effort to reproduce as quickly as possible. Bolting often occurs prior to harvest when radishes are planted too late in the season.

Radishes that are bolting will not taste as good, and the roots will be smaller than if the plant had not bolted.

If you see your radishes bolting, you can try to shade them with a row cover or light cloth to diffuse the sun and help delay the process. However, you cannot stop it once it has begun.

Do Different Varieties of Radishes Need More or Less Sun?

Yes. When it comes to sun exposure, different varieties need more or less sun. 

While it’s true that many radishes can tolerate partial shade, some radishes actually prefer full sun.

This is because radishes are a root vegetable, and their roots need plenty of sunlight in order to grow large and succulent.

In addition, radishes that are grown in full sun tend to have a crispier texture and a milder flavor.

Raphanus sativus, the scientific name for the common radish, is classified as a cool-season crop.

This means that it grows best in temperatures between 60 and 70 degrees Fahrenheit. It does best with around the usual six hours of sun. 

However, some varieties of radishes can tolerate slightly higher temperatures.

For example, the black radish (Raphanus sativus var. niger) is more heat-tolerant than other types, and can even be grown as a summer crop in some regions with correspondingly higher sun exposure.

When choosing a radish variety for your garden, be sure to select one that is well-suited for your climate and soil type. With so many versatile cultivars available, there’s no need to settle for anything less than the perfect one.

What Happens if Radishes Donโ€™t Get Enough Sun?

Radishes that don’t get enough sun will grow many more leaves or “tops” than root. some might not grow a root at all!

The flavor of the radish may also be affected, usually becoming more bitter with a spongy texture.

Can Radishes Grow in Indirect Sun?

Yes, and some cultivars in particular do quite well with indirect light, indoors and out. These include the Cherry Belle, Scarlet Globe, and White Icicle radishes. Dappled shade is just fine for these varieties.

When grown indoors, radishes will need to be near a sunny windowsill or grow light in order to thrive, and preferably one that gets high-value sun for not quite half the day.

Radishes grow quickly and do quite well indoors, and if you want to you can eliminate the sun requirement entirely by utilizing a grow light.

Transitioning Radishes from Indoors to Sunlight

If you have been growing radishes indoors under grow lights, you will need to slowly acclimate them to outdoor conditions by gradually increasing the amount of sunlight they receive each day.

This process is called “hardening off” and it helps prevent shock to the plants.

Start by putting the plants outdoors in a shady spot for a few hours the first day, then increase the time each day until they are able to tolerate being in direct sunlight for several hours.

This process usually takes about a week for radishes. Once the plants have been hardened off, you can transplant them into your garden or full-time outdoor container.

If you fail to harden off your radishes before transplanting them, they may go into transplant shock and become stunted or even die off entirely.

It seems like a chore, and it is, but it is vital to the success of your plants, particularly ones like radishes that have a short growing season to begin with.

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