By Dr. Mercola
While known as a salad green with a tangy, slightly peppery kick, arugula1,2 is actually a relative of the cruciferous family, which includes radishes, Brussels sprouts, kale, cauliflower and broccoli. Like other members of this family, arugula contains a number of medicinal nutrients, including cancer-fighting compounds and carotenoids known for their importance for good eyesight.
It’s an excellent source of fiber, vitamins A, C and K, folate, calcium, iron, magnesium, phosphorus, potassium and manganese. Arugula also provides high levels of protein, thiamin, riboflavin, vitamin B6, zinc, copper and pantothenic acid (vitamin B5).3
Its flavonoid content helps improve blood vessel function, increase blood flow, lower blood pressure and lower inflammation. Arugula even has cleansing properties to counteract the poisoning effects of heavy metals in the system, particularly in the liver,4 and helps eliminate pesticides and herbicides from your body.
Arugula has long been considered an aphrodisiac, and modern science supports this notion, showing trace minerals and antioxidants help block absorption of environmental contaminants suspected of impacting your libido.
Arugula Is a Heart-Healthy Food
Arugula also contains about 480 milligrams (mg) of nitrates per 100-gram serving, which your body uses as raw material to make nitric oxide (NO),5 an important biological signaling molecule that supports normal endothelial function and protects your mitochondria.
Acting as a potent vasodilator, NO helps relax and widen the diameter of your blood vessels, supporting healthy blood flow and oxygenation of your tissues. It also carries away waste material and carbon dioxide. A diet high in nitrate is a natural strategy recommended for the treatment of prehypertension and hypertension6,7 (high blood pressure), and helps protect against heart attacks.
Raw beets are perhaps the most well-known for their ability to lower blood pressure (thanks to their nitrate content), but arugula actually contains the highest levels of nitrates of any vegetable. For comparison, 100 grams of whole red beets provide a mere 110 mg of nitrates to arugula’s 480 mg.8
How to Grow Arugula
Arugula9 is a cool season crop, and can be added to your fall garden plantings. It’s forgiving in that it can tolerate low-fertility soils and frost, and is really easy to care for, although it does best in humus-rich soils with a pH between 6 and 6.8. Seeds germinate best at temperatures between 40 and 55 degrees F. Plant your seeds directly into your garden bed, but avoid planting them in a spot where you just harvested another cabbage family crop.
As noted in the video above, there are two main types of arugula.10 Common arugula (Eruca sativa) is best for eating and cooking, as it produces large, lush growth, while the wild Italian arugula (Eruca selvatica) — which does have a bolder flavor — tends to be more stemmy. The Italian variety will also bolt faster.
Plant your seeds about one-fourth inch deep, 1 inch apart. Rows should be about 3 inches apart. Seedlings will sprout in about 10 to 14 days. Arugula will do well planted next to lettuce and peas. For a continuous harvest through the fall, plant new seeds every two weeks up until about four weeks before your first frost date. Dry, hot weather will speed bolting. If temperatures are still on the high side, you can slow bolting by providing shade and making sure the soil doesn’t dry out.
A common cabbage family pest is the flea beetle. Row covers can be used to protect tender seedlings. Another protective measure is to sprinkle food grade diatomaceous earth around the seedlings. Diatomaceous earth is available at most garden centers. One drawback is that it will kill any soft-body insect, so in addition to fleas, it could also have a detrimental effect on worms and even bees. For this reason, it’s best to use it only when absolutely necessary.
Another alternative suggested in the video above is Reemay fabric. Used as a row cover, it allows about 75 percent of sunlight through, and is permeable enough to allow water through — but not the pests. Simply pin the fabric down so that it’s loosely covering the plants, allowing for growth.
Harvest — and Eat
Mature arugula is ready to harvest in about 40 days. “Graze” harvesting means selectively picking just a few leaves here and there to add to your cooking. The smaller the leaf, the milder its flavor will be. Alternatively, use a pair of garden shears to cut back about one-third of each plant, selecting the largest leaves in each bunch. The remainder will continue to regenerate and grow back.
Once the arugula starts to flower, it’ll start turning bitter. At this point, your best option is to pull the whole plant out by its roots. Salvage whatever leaves you still find edible and compost the rest. The arugula tends to bolt quickly, so keep an eye out for the telltale signs of flowers (shown in the video above), and harvest right away. Ideally, harvest at a time when it’s cooler and shadier, as the leaves will wilt quickly when cut in full sun.
Arugula is a popular salad green, but can be added to any number of dishes, such as sandwiches and hot or cold pesto, although it will lose some of its peppery punch when cooked. For a delicious side salad, try my grapefruit and arugula salad with avocado recipe.
How to Save the Seeds
Arugula seeds are easy to collect and save, and can be stored for up to five years. The plant will produce small, white flowers. Once flowers emerge, small seed pods will start to form along the stem. If you like, you can actually eat the seeds. They have a strong spicy kick, similar to a radish. Once the plant bolts, the leaves will turn bitter and begin to brown.
There are a number of ways to collect the seeds. Some will cover the stem with a nylon stocking to catch the seeds as the pods break open. Alternatively, clip the stem, tie a paper bag around it and hang upside down to dry.
To check if the seeds are ready to be collected, gently shake the seed pod. The seeds are ready when you hear them rattling around inside the pod. Eventually, the pods will break, releasing the seeds, or you can crush the pod if you like. To separate the seed from the chaff, Heirloom Organics suggests the following method:11
“If your seeds are in a bag already, you can shake the bag or stick your hand in the bag and crumble the dried seed pods. You'll end up with a pile of tiny dark seeds mixed in with papery seed pod chaff.
To separate this out, you can do it the old-fashioned way, which is to put everything in a shallow pan and blow the chaff off the top of the pile. The seeds weigh more than the chaff, so they will stay put. Another way is to put them in a sieve that has holes bigger than the seeds, but smaller than the chaff and shake.”
Store your seeds in a paper envelope or jar in a cool, dark, dry place. Alternatively, store them in a zipper bag in your refrigerator.
Try Arugula Microgreens
A simple and inexpensive way to boost your nutrition is to grow microgreens. Any regular herb or vegetable, including arugula, can be turned into a microgreen simply by harvesting it while the plant is still young. It’s simply a matter of not waiting until it’s fully mature. A microgreen or “baby” green is harvested when just a week or two old, when it’s reached a height of about 2 to 4 inches.
Many of the benefits of sprouts and microgreens relate to the fact that, in their initial and early phase of growth, the plants contain more concentrated amounts of nutrients.12,13,14 Vitamins like A, B-complex, C and E also increase in sprouted foods, sometimes by 20 percent within just a few days of germination. As a result, you need to eat far less, in terms of amount, compared to a mature plant. As noted in the book, “Microgreens: Novel, Fresh and Functional Food to Explore All the Value of Biodiversity:”15
“Microgreens are … increasingly used by haute cuisine chefs to prepare gourmet dishes intended to satisfy the needs of modern consumers, more and more health conscious and particularly attentive to their health, diet and food quality.
Although [they] are often used with the main aesthetic purpose of garnishing dishes, microgreens also have a very good nutritional profile and … are considered ‘functional foods’ or ‘super foods’ as … they can also provide bioactive compounds able to improve some functions of the organism and/or reduce the risk of diseases.”