How to Grow Watermelon Radish

We just planted a new mini patch of watermelon radish in a small decorative wagon because are little garden thought it would look nice. It was a really cute idea and looks nice. What he doesn’t know is we have used the wagon to plant things in in the past. It’s prefect for fast growing vegetables like watermelon radish.


Watermelon radishes grow best in full sun. Wether you are growing them indoors or out they will need 6 to 8 hours of full sun light everyday to grow.


You can grow watermelon radish in a large verity of soils. Garden soil that you can get in the store will work as well as the soil in your back yard. It is recommended that you use a sandy soil with compost added in which would also work really well for container growing as it drains well. However watermelon radish will grow just fine if you don’t have a sandy soil.  


When sprouting radish seeds it is recommended by others that you sow them ½ inch apart and thin them to 3 inches apart. We don’t like wasting seeds our plants especially edible plants. For this reason we sprout our seeds in indoors or in a green house using paper towels are seed beds. This allows us to transplant the sprout into planters, pots, or the garden at 3 inches apart without thinning them.


Watermelon radishes like to be moist but not soaking wet. You should water them everyday making sure not to have them standing in puddles all day when you are done. If you live in a rainy environment and you have planted them outdoors it is important to use a well draining soil. When we live in Canada it rained most of the time and we had the radishes outdoors in raised garden beds. We made our own garden beds and left room on at the bottom for water to pour out and used a soil rich in compost that drains well. When it wasn’t raining we had to water them to make sure they didn’t dry out but they never puddled which is the most important part.


Rich soil with plenty of compose is prefect for radishes as they need a lot of nutrients to grow as most root vegetables do, because they live under ground.

Annual or Perennial

Watermelon Radish is annual because once they are grown if they aren’t harvested they will rot. You can let some of them grow until they go to seed but that is also risky as the could rot before they seed.

Climate/ Hardiness

Radishes have a very short growing season and can be grown and harvested many times during the year. They can tolerate soil temperatures of 40°F/4°C but germination at that temperature could take longer. At lower temperatures germination can take up to 10 days, in warmer temperatures like around 75°F germinate can take as little as 3 to 5 days.


Like germination harvest times will also depend on soil temperatures with days to harvest being anywhere for 50 to 70 days. We have seen them grow to harvest and short and longer timeframes around 40 to 90 days. It best to check them every 10 days after day 40 or 50 to make sure they don’t start to rotting in the soil.


It is commonly not recommended to transplant watermelon radish after they have started to root. However sometimes there may be an emergency and you may need to. If this happens keep in mind that radishes can root at a depth of 8 to 10 inches are sometimes more. They have a main root that is thicker than they others and if cut it will stop growing. If an emergency transplant becomes necessary turn to dig around them at a width of 4 to 5 inches and a depth of 11 to 12 inches as to try not to break the roots.    


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