For a bit of added pep in your salads, spicy arugula is a must-have plant for your garden. Sometimes known by its scientific name of Eruca sativa, arugula is easy to grow and is popular throughout the Mediterranean region and further north, where it thrives in cooler temperatures.

Arugula is related to cruciferous vegetables like kale, cabbage and cauliflower, giving it more nutritional impact than most lettuces. It contains several vitamins and minerals that can improve health and has a reputation as a detoxifier and aid to bone health.

Planting Arugula From Seed

Arugula is so fast-growing that it appeals to gardeners who have a need for instant -- as much as is possible in gardening -- gratification. From planting to harvesting takes about four weeks. This rapid growth has earned it the nickname "rocket," which the herb is commonly known by in some parts of Europe and the South Pacific.

Seed Sowing Depth

Keep arugula seeds close to the top of the earth so they can get plenty of sun. You won't need to plant them more than 1/16-inch to 1/8-inch deep in well-tilled soil. In fact, some arugula gardeners simply broadcast the seed to an area of the vegetable or herb plot and thin the seeds as they grow.

When and Where to Sow Arugula Seeds

Cool weather is just fine with arugula. It can grow in warmer climates but does best where it can get sun without the high temperatures. You don't even have to worry about planting after the first frost -- it can survive a cold night or two.

Because of how quickly arugula grows and its ability to withstand a little frost, it's best to plant the seeds directly outside as early as late March or April. Before you sow, work in plenty of high-quality compost to enrich the soil and make it better able to retain moisture. In general, arugula prefers to be slightly moist.

You'll need to sow a new crop of arugula every 2 to 3 weeks in the summer to ensure you have a plentiful crop available to harvest throughout the season. While it's possible to plant starts indoors, you're likely best served to have different rows of the garden devoted to arugula in its various stages.

The Basics of Arugula

Plant Height and Width

Arugula is a small plant that typically stays under 12 inches tall and can spread to about 12 inches. It should be spaced at least 6 inches apart and rows should be set 18 inches away from each other. When it bolts, the flowers can grow up to 24 inches tall.

Leaves and Flowers

The compound, or pinnate, leaves of the arugula plant and form four to 10 lobes around a center with a larger lobe at the end. Color varies from a very pale green -- almost white, especially if sunlight has been filtered -- to a more robust light green shade. Leaves are edible in their entirety and don't need to be removed from the center stem.

If allowed to bolt, or go to seed, arugula will form small white flowers with light purple veins. The flowers can be pinched off as buds to extend the plant's life or allowed to continue growing and be harvested for seed.

Growth Habits

Arugula forms a moderately mounding, close-to-the-ground plant until it's time to bolt, when it shoots up stems with flowers and becomes spindly.

Caring for Arugula

While arugula enjoys a cooler climate, it also needs plenty of water to keep it looking and tasting its best. Most leafy plants like arugula perform ideally when well watered; just take care to keep from saturating the ground and giving mold and fungus a good place to take hold.

Regular and plentiful watering also helps dilute the bitterness of arugula and helps you produce a less spicy and more tasty plant.

Pests and Diseases that Impact Arugula

Pests that Eat Arugula

• Flea beetles. Flea beetles will eat the newly sprouting arugula plants before they ever have a chance to grow. If these pests are a problem in your area, wait a few weeks to plant your seeds or cover the seedlings with plant fabric.
• Cabbage worms. These pests attack lettuces and cruciferous vegetables, but you can manually remove them when you see them.

Diseases that Harm Arugula

• Leaf spot. This bacterial infestation manifests itself as small brown spots on leaves and usually takes root when water is allowed to sit on leaves. Water close to the base of the plant and try not to let water sit on the leaves.
• Downy mildew. Spores travel through the air and alight on less healthy plants, forming brown spots on top and gray fuzzy areas under leaves. As with leaf spot, prevent problems by keeping leaves dry and watering from the base of the plant. Also avoid planting too close together and make sure to thin seedlings appropriately.
• White rust. This fungus impacts cruciferous vegetables including arugula; you'll see it show up as white spots underneath the leaves. You can apply a fungicide to the soil to eliminate the problem in future crops.

Harvesting and Storing Arugula

Once the arugula plant has several sets of leaves, you can start harvesting. Small leaves usually taste best and are not as bitter or spicy, so it's recommended that you harvest the outside baby leaves a few at a time while you leave the center to grow longer.

Leaves will keep well in the refrigerator for up to a week. As with lettuce, there's really no good way to preserve arugula. You can't freeze it or it will become mushy and it's challenging to successfully dry, though some people give it a go in an oven at a low temperature. Dried arugula can be used in soups and sauces. But for the most part, you'll be best served picking and eating it fresh.

Uses for Arugula

Arugula is commonly used in salads, but the Italians add it to pizza just before it's finished baking and to pasta sauces just before they're done simmering for the added taste. In Slovenia, it's often added to soup.

Residents of Ischia, a small island off the coast of Naples, incorporate arugula into a sweet digestive alcohol famous in the region. It's taken in small amounts just after a meal, much like a grappa in other parts of Italy.

In addition to being an ideal component of a mixed salad due to the added spice it lends, arugula is packed with vitamin C and potassium. The nutritional punch it packs and its long history of cultivation gave arugula a reputation as an aphrodisiac amongst ancient peoples; in fact, monks in the Middle Ages were prohibited from growing it. Today, scientists have found that the phytochemicals in arugula may be able to fight some forms of cancer and recommend incorporating it into the diet for these benefits.

Because all parts of the arugula plant are edible, some areas incorporate the flowers or seeds into dishes. The seed can be used for flavoring oils or can be made into a cake that is used primarily to feed animals.