Radish 
Radishes need to be grown steadily and harvested young to ensure they remain succulent, otherwise they can become woody and inedible.
Sow little and often and make sure they grow well without any checks to their growth.
Because radishes are quick to mature they can be used as a 'catch crop' being sown between rows of slower-growing vegetables such as peas and potatoes.
They can even be used as row markers of slow-germinating crops, such as parsnip and onion - the radishes germinate quickly, marking out the row where the other crops have been sown and can be pulled before interfering with the main crop
There are also winter cultivars (mooli) whose large roots can be used raw or cooked.
