Arugula is slightly sensitive to the cold and wind, it is best to plant them outdoors when the weather is fair.  Between May 8th – May 22nd  is the optimal time to prevent cold and wind damage.

Always go by the weather, if the weather is poor during this time postpone planting or if the weather is fair before these dates plant early.

Plants that have been properly hardened off are less susceptible to cold and wind damage.