Arugula & Watercress Seeds

Characteristics

• Both watercress and arugula have small, rounded seeds about 1/16th to 1/8th of an inch in diameter and are found in shades of tan and brown. They share many characteristics with radishes, mustards and other spicy members of the Brassicaceae, or cabbage, family, including high germination rates and the inability to sprout in hot weather. Both seeds can be used to make "sprouts," the practice of harvesting seedlings just after they germinate for use as a garnish on salads and sandwiches.

Germination

• Arugula germinates in five to seven days at temperatures between 40 and 55 degrees Fahrenheit. Sow it in the place where it is to be grown as soon as the ground can be worked in spring. Watercress needs a little more warmth to germinate and can be sown indoors three weeks before the average last frost date or outdoors once all danger of frost has passed. Both seeds should be planted 1/4 inch below the soil surface.

Seed Production

• Arugula sends up flower stalks and sets seed very quickly if it does not receive enough water or when temperatures rise above 85 degrees -- a phenomenon known as “bolting,” which causes the leaves to become tough and bitter. Planting in partial shade helps to delay bolting in arugula. Watercress flowers and sets seed in late summer. In cool, moist soil conditions, both plants will sprout from fallen seed in the areas where they are grown.

Saving Seed

• Watercress and arugula seed can be saved using the same process. Allow the seed to ripen fully on the plant. This is evident when the seeds appear plump and fully rounded in their seed pods. Don't let the seedpods dry on the plant until they are completely brown because they will open and spill the seeds on the ground. Instead, cut the stalk 6 inches below the seed pod and hang it upside down in a paper bag for two or three months in a dry place. Shake the stalks inside the bag to release the seeds and store them in a cool, dry environment for planting the following year.