There’s nothing subtle about arugula. Dark green and intensely flavored, the lobed leaves may well be an acquired taste—and whether or not you enjoy them could depend on your first bite. Small young leaves give a peppery edge when mixed with lettuce under an oil and balsamic dressing, but older, overgrown arugula has a tang and bitterness that’s harder to appreciate. Arugula (Eruca vesicaria ssp. sativa), or rocket as it’s sometimes known, is closely related to watercress, mustard greens, and radishes; and like other leafy members of the Brassica family, goes from tender and gently pungent to tough and hot as it ages.
Unlike most salad vegetables, rocket seeds are tiny, so be careful not to plant them too deeply. Place thin seedlings up to about 10 cm long in rows to cover and tunnel the rocket before planting, if they are to be used as salad vegetables. Keep them planted 4 inches apart and grow young leaves to about 6, then go ahead and ripen the leaves from the seeds.
Plant rocket seeds in the soil, which works best in spring during the first years of harvesting. To grow arugula, sow plants with enough time to form a healthy canopy of leaves at high temperatures to trigger flowering. Direct sowing of seeds in spring soil, which works best, or start sowing indoors 12-8 weeks before the last frost of spring, protected by a plastic tunnel.
Growing arugula from seeds is quick and easy, but it is best to sow seeds in a garden in spring when the risk of severe frost is over. Start with a packet of seeds and plants or sprinkle the seeds in a well-prepared garden bed and pat the seeds with your hands. If you love arugula you can do this one after the other by sowing more seeds every two weeks to get the most out of the growing season as long as the mild temperatures continue to be.
When flea beetles eat your arugula, they leave distinctive small perforated flowers and you can protect your plants in one of two ways. Either arugula grows in old beds or the seeds are treated and planted in an area with useful mycorrhizae such as mycostop to reduce the likelihood of pythium attack.
Avoid arugula, where cabbage, collar, broccoli, or Brussels sprouts grow. Slurry, compost, and organic material should work well in the soil before planting arugula before the season starts. Before sowing rocket seeds, gardeners should apply several centimeters of rotting slurry, aged compost, or fish emulsion (nutrient-rich organic material) to the soil in which the rocket is planted.
If you have cool weather, chances are your plants will grow back and give you baby rocket leaves in just a few weeks. Once they have received fertilizer, rocket plants should be processed with organic material as soon as they are planted. About two weeks after they have their first real leaves, gardeners should apply a balanced, water-soluble granulate fertilizer.
During the cool season, arugula plants will stop producing when the weather gets warmer. If you want the longest production time of your arugula, pull the entire plant and harvest it by picking the outer leaves.
Arugula leaves can be harvested when they are about 2-3 cm long and about 2-3 weeks after the plant has sprouted under ideal conditions. Arugula has a flat root system, so it is not difficult to raise a plant for a large harvest. Rocket leaves should be picked early in the plant season before the entire plant has been harvested.
In most cases, the majority of the root system of an arugula plant is located within the top six centimeters of the soil. Rocket plants are comfortable in well-drained soil, which is acidic to neutral with a pH value of 60-70.
Arugula tolerates a variety of soil types and likes them so rich that no additional compost or nitrogen fertilizer is required. If you plant arugula in nitrogen-rich soil, you do not need additional feeding.
Rocket, called rocket or roquette, can be planted in the garden in spring or autumn. Arugula plants are low-growing and have pale green leaves that blanch to a white lid when fully grown.
If you are curious about how to grow arugula, but your plants have not yet started, you should look at this guide to planting and growing arugula from seeds. If you have a container for growing trees, plant your arugula in tasty and attractive soil that needs to be covered.
Arugula is a plant that thrives in mild climates, so it is best to start from seeds. Depending on the variety you plant, your rocket should be ready for harvest in 20 to 50 days after sowing.
Arugula plants are best grown in full sun (they get at least six hours of direct sunlight a day) and produce leaves that are very fast, but they can also grow in partial shade. In late summer, arugula can be sown in a shady cloth to plant early and prepare for the autumn harvest. I pull and twist the screws of an arugula plant in spring and leave a couple of plants to produce seeds for the autumn harvest.
The ideal temperature range for rocket plants is between 45 and 65 degrees Fahrenheit. In cool weather, the arugula planted will be green and develop at temperatures between 45 and 65 degrees Fahrenheit. Arugula plants thrive best in well-drained soil, but they also like plenty of moisture and water.
Plant arugula at intervals of about 12 to 18 inches in a sunny location in fertile, well-drained soil. Plant about a quarter of a centimeter deep and cover the plants with a light layer of fine soil.
Arugula is rich in soil and organic matter and has a good taste because it is not stressed by heat or lack of water. When rocket leaves are chopped at the end of the season and processed into heaps or compost heaps, they become a natural biofumigant that suppresses disease through mustard oil and glucosinolates. The leaves taste like burnt tyres, and gardeners urge me to try harvesting baby arugula next time.
The secret is to grow a small patch, pick the leaves at their tender best and root out the plants when they become unpalatable; then to have a second and third patch coming along in succession. Fortunately, arugula is a simple green to cultivate from seed, sprouting quickly and growing vigorously like the half-wild thing it is.
When to plant
A true cool weather plant, arugula does well at both ends of the growing season, May through June and then again from September to November across most of Canada. Cool-weather and abundant moisture impart a mild, nutty flavor, distinct but good, while midsummer heat and drought make for leaves so strong-tasting that you might just spit them out.
Given their ability to germinate at soil temperatures as low as 10°C, arugula seeds should be one of the first in the ground, about the same time as spinach seeds and onion sets—around mid-April in our Zone 5 garden, or a full month-and-a-half before frosts are over. But frost is no threat to small arugula plants, and an April seeding brings leaves to the table by the May long weekend, traditionally the time to be “putting in the garden,” not picking.
The soil for arugula need only be moderately fertile, friable and reasonably well-drained; in many gardens, little or no amendment may be necessary. Plant seeds in either a band about a hand-span wide, or a small rectangular or square patch, and let your taste for arugula determine the space you give it. As always, careful seeding saves a lot of tedious thinning later on. Scatter or drop seeds singly over the area, aiming for roughly 2.5 centimeters between them, then cover lightly with no more than a half-centimeter of soil. Soil moisture or spring rains should be enough to push them through, but a gentle watering or two, especially on the morning of a warm sunny spring day, may speed germination.
How to grow arugula
As arugula grows, there are several ways to proceed. For baby arugula, thin seedlings just a little, leaving four to six centimeters between them, and then harvest young leaves with scissors. Cut just above the crown, the young plants will grow new leaves that can be cut again. For full-sized plants and leaves, thin eventually to 10 centimeters and pluck individual leaves from the sides of each plant. A weekly soaking promotes lush growth and milder flavor, while a mid-growth drink of dilute fish emulsion will spur plants on.
Quick growing arugula is useable as small leaves in as little as three weeks. After 40 days the plants are full-grown, and the window of harvest lasts another couple of weeks. The tastebuds know when the leaves are beyond eating. A small seeding every 10 days or so, until about the first of June, keeps a fresh supply coming along, and just after Labour Day is the time to sow again. Arugula revels in the cool damp days of fall, growing slowly and standing fresh and fine long after most of the rest of the garden has called it a season.
Arugula’s growth is generally healthy and strong, but the tiny black flea beetle can pose a serious threat, descending in great numbers and riddling the leaves with little holes. Flea-bitten arugula is about as appetizing as slug-chewed lettuce. This is where a sheet of floating row cover does its best work. Finely spun threads bonded together mean the sheer fabric floats lightly over plants, letting in sunlight and rain while blocking flying insects. Easily cut to fit, the translucent cloth is reusable for years.
There are only a handful of arugulas, the basic wild rocket, and a few improved types. Although no arugula can stand the blazing sun of midsummer, ‘Skyrocket’ and ‘Astro’ are both described as more heat tolerant. ‘Surrey’ is said to be milder, but with arugula, it’s all about the weather and water.
Let it Seed
Arugula is still close to its wild roots. If you can handle a bit of randomness, allow a plant or two to run to flower and seed. Collect the seeds to resow, or let them fall where they will and watch for the naturalized seedlings to spring up—where you want them and where you don’t.