Horticulture Magazine

How To Grow Rocket

Wild arugula rocket leaves

Arugula Overview

Official Plant NameEruca versicaria var. sativa
Common Name(s)Rocket, Arugula
Plant TypeVegetable
Native AreaMediterranean
Hardiness RatingH4
ToxicityEdible
FoliageAnnual, doesn’t overwinter
FlowersWhite flowers
When To SowApril, May, June, July, August, September
Harvesting MonthsJune, July, August, September, October, November, December
Sunlight

Preferred
Full Sun or Partial Shade

Exposure
Exposed or Sheltered

Size

Height
0.5 – 1M

Spread
0 – 0.1M

Bloom Time
Summer

Soil

Preferred
Most Soil Types

Moisture
Moist but well drained

pH
Any

If you like pepper, spice, and leafy greens, Bingo! Your prize is Rocket, a plant whose leaves have a spicy, peppery kick. These leaves can be cooked in casseroles or tossed raw in salads. An ever-increasing variety of Rocket cultivars provides an array of differentiated flavours so that if one variety is right to serve haddock on, another is ideal to cook venison with.

‘Rocket.’ That sounds much more appropriate than ‘Eruca vesicaria’ doesn’t it? The name ‘Rocket’ has a bit of a zing – just like the leaf itself! With a pleasant kick that can be variously peppery, spicy, tart, tangy, and even pungent, this leafy green is both a herb and a salad leaf. 

Perhaps another good reason to call this herb cum leaf Rocket rather than some Botanical name is because of the disagreement and confusion over its status and name. Is Garden Rocket or Salad Rocket a species in and of itself or a sub-species? Is it Eruca sativa or Eruca vesicaria subsp. sativa? Then again, it cuts both ways because Rocket is also the vernacular name for varieties of Hesperis matronalis, a flowering plant, Diplotaxis tenuifolia, a different but similar leafy green, and, indeed, nearly 20 other plants! Almost all of these ‘Rockets’ are edible leafy greens with a sharp flavour.

As for Diplotaxis tenuifolia, it is a perennial that is called ‘Wild Rocket.’ It has a sharper, more intense flavour than Salad Rocket and its varieties. Plants of both genera, Eruca and Diplotaxis, are classified under Family Brassicaceae – the Mustard Family. It is little wonder that these plants’ leaves (and other parts as well) have the sharpness and pungency, to some or another degree, that we associate with mustard. 

This article concerns itself with both kinds of Rocket. Though Salad Rocket or Garden Rocket is the more widely-known and widely-grown, Wild Rocket is seeing an upsurge of interest. Varieties of both Rockets grow from 25 to 80 centimetres high. 

rocket leaves on a white background
Salad Rocket or Garden Rocket Leaves

Confusion and Clarifications

Salad Rocket’s leaves are whole and scalloped to some or another extent. Wild Rocket’s leaves are rather different, being sharply parted, sometimes called lobed, and serrated. However, newer cultivars of both Salad Rocket and Wild Rocket have leaves that are from slightly different to starkly different than those of the respective parent species. Therefore, even here Rocket varieties include such exceptions that it would be very easy to confuse oneself in trying to classify them by the shapes and types of the leaves. For example, the narrow, deeply-parted and sharply-serrated leaves of Salad Rocket ‘Uber’ look much closer to those of Wild Rocket while the whole and slightly-serrated leaves of Wild Rocket ‘Olive Leaf’ are closer to those of Salad Rocket!

We are not through with the confusion just yet. If you ever hop over the Pond, going to a supermarket and asking for ‘Rocket’ may well draw stares of concern at your state of mind. Remember to ask for ‘Arugula’ which is what North Americans call Rocket. Though ‘Arugula’ may sound like the Italian word for Rocket, this name is used only in a small region of Italy. In Italy the plant (and its leaves) is called Rugola or Rucola. 

Salad Rocket’s flower has four long and narrow splayed petals. It resembles nothing so much as a bi-plane’s four-blade propellor in miniature. The petals are of an off-white colour with delicate purple veining. Wild Rocket’s four-petalled flowers are yellow and its petals are shorter and curved compared to those of Salad Rocket. Rocket varieties’ flowers are also edible and flavourful. They can be, and often are, used as a decorative garnish. And, finally, even the seeds and seed-pods are edible. Seeds can be crushed and made into a type of mustard.

white plate with a freshly picked arugula salad
Wild Rocket Leaves

Background and Origins

Rocket has gained a following in the United Kingdom during only the past several decades. Rugola, as it is called in Italy, has been enjoyed as a leafy green as well as a salad green in Italy at least since the time of Virgil and Ovid, during the Age of the Caesars. In fact, Rocket used to be consumed in quite a different way as well: it was thought to be an aphrodisiac since Ancient Times. Perhaps it was one of the ingredients in Tristan and Isolde’s love potion?

Rocket species are native to Italy and the Mediterranean regions. They, particularly Wild Rocket, are tough plants that can thrive in poor-quality soils. They colonise all kinds of ground so rapidly that they are considered weeds or invasive plants in some parts of the world, such as Australia and Arizona.

These plants, having spread from their native regions, now grow readily in temperate locales in both the Old World and the New.

Common Varieties

Over the past decade or so Rocket has – ahem! – ‘rocketed’ in popularity in the United Kingdom, and keeping pace with the demand, an increasing number of cultivars have come on the market. These differ not only in their sharpness and pungency but even in their respective flavours. As a result the general rule of Wild Rocket being sharper and more peppery than Salad Rocket no longer holds true because one or two cultivars of Wild Rocket have fairly smooth, mild flavours while a few varieties of Salad Rocket are rather spicy and zingy.

One general rule that does hold true is that for any given variety, the younger and smaller the leaf and the earlier the harvest, the more tender the leaf and its texture and the sharper but ‘lighter’ and more subtle the flavour; the later the harvest and the more mature and bigger the leaf, the rougher the texture of the leaf and the more pungent and more developed but also the ‘heavier’ its flavour.

Salad Rocket or Garden Rocket has bright, light green leaves that are gently scalloped. They are also ‘gently’ peppery with but a mild spiciness or tartness. Flavour-wise they are not intense but pleasant, but they must be used relatively fresh otherwise they lose their pleasant pepperiness and develop a harsh taste and texture. 

Wild Rocket’s dark green leaves are very deeply parted and serrated. In taste they are peppery and pungent in addition to which they also have a spicy aroma. Flavour-wise this natural variety’s leaves have a tingling intensity, and cut leaves retain their freshness and sharpness for longer than those of Salad Rocket.

pasta, olives, feta, rocket and tomato salad on a black plate
A Starter Doesn’t get any More Colourful, Appetising, and Healthy than this

Salad Rocket ‘Uber’ has heavily- and sharply-parted mature leaves that are closer to those of Wild Rocket than to Salad Rocket. Their medium greyish-green colour too is unlike that of Salad Rocket. But in taste they are not only very far from Wild Rocket, even for Salad Rocket ‘Uber’s flavour is mild and refined. 

Salad Rocket ‘Esmee’ Organic has bluish-green leaves which are heavily parted and sharply serrated. In view of ‘Esmee’ Organic’s ‘medium’ sharpness and its balance it is perhaps the best variety for inclusion of raw leaves in salads and such, whether comparing fresh young leaves or mature leaves to the equivalent of other varieties.

Salad Rocket ‘Pronto’ has bright, almost shiny, green leaves that are moderately parted. The leaves are distinctly peppery and their sharpness or pungency falls squarely between Salad Rocket and Wild Rocket. All three properties, flavour, colour, and shape of the leaves makes ‘Pronto’ especially attractive for salads.

beef burger and fries on a wooden tray
Spice up that Burger with Rocket

Wild Rocket ‘Olive Leaf’ is a remarkable outlier in the Wild Rocket family. Neither its leaves nor its flavour are anything like those of Wild Rocket! But ‘Olive Leaf’ is indeed a member of that family because it is a perennial but its slightly-scalloped light, bright green leaves are closer to those of Salad Rocket. The aromatic leaves’ flavour is peppery yet nuanced.

Wild Rocket ‘Giove’ has narrow, parted, and serrated leaves of a deep, medium green shade. Going against ‘family principles,’ in taste ‘Giove’ ranks among the subtlest, having the mildest of pepperiness. In fact, it has a proper leafy-green taste and texture, with a hint of sweetness. Great for light salads.

Wild Rocket ‘Wasabi’ has brilliant emerald green leaves that are narrow and serrated but not parted. In taste ‘Wasabi’ is actually very much like its namesake, being not only peppery but having an intense pungency. It can be and, indeed, actually is used as a substitute for Wasabi in Japanese cooking. Great for cooking with meats.

olives, egg and toast on a bed of rocket
Here’s how you can have Rocket at Breakfast

Habitat and Growing Conditions

In the wild, Rocket happily grows in fields, roadsides, embankments – any which where. Obviously, it is not fussy about soil or growing conditions.

A halfway decent loam mix will be just fine for growing Rocket plants in. For optimum results prepare a loose soil with some organic manure, chalk, humus, and sand. Soil should drain well.

Soil pH may range from Slightly Acidic to Slightly Alkaline.

The plant will grow well in full sun and also part shade.

How to Grow Rocket

Salad Rocket can be sown in a heated frame from February and outdoors from April onwards. Whether you sow it in beds or pots, both the plant and its use lend themselves to successional sowing. It may be sown every two to three weeks for a continuous supply of fresh leaves through to autumn.

If planting in a bed, sow seeds in rows. Cover seeds loosely with a layer of soil of about 0.5 centimetre. Seeds should be sown 3 to 7 centimetres apart and rows spaced about 30 centimetres apart. 

If planting in pots, sow seeds two or three to a terracotta pot of about 25 centimetres diameter.

Give the freshly-sown seeds a good watering so that the soil becomes well wet.

Watering Salad Rocket, an annual, can be a tricky balancing act. If plants are not watered well enough and the soil becomes dry, they will bolt (run to seed). On the other hand, keep watering them a little too well and the leaves will lose their kick and become bland. The trick is to keep the soil just moist.

Weed the bed or pots as you normally would.

As the seedlings grow, thin them so they are about 15 centimetres apart or one to a pot. (The thinnings should not find a place in your compost pile but on your kitchen table!)   

If the weather gets hot and your plants are exposed, they must be protected from the hot afternoon sun otherwise the leaves will lose their tenderness and flavour.

You can also start off Salad Rocket in autumn. It can be grown indoors in pots in a sunny spot that gets sufficient sunlight through the morning, and can be grown outdoors if it is protected by horticultural fleece.

Wild Rocket may be grown the same way except that as it is a perennial you do not need to worry about sowing it again the following year. They are also not prone to bolting. Grow as many plants as you need and then judiciously harvest leaves as you need them on a true ‘cut and come again’ basis. 

As long as a Wild Rocket plant is not severely harvested or over-harvested it will survive through the winter if it is protected with fleece or in a cloche, and continue supplying you with greens the following spring.

white eruca sativa up close
Is that a Flower or a Biplane’s Propellor?

Harvesting Rocket 

Leaves from plants are ready for picking about one month from sowing.

Pick bigger, older leaves for a more intense taste and for cooking purposes; Rocket can be cooked like spinach. Pick smaller, newer ones for a gentler flavour for using raw in salads or as garnish.

Pick two or three leaves from each plant, harvesting several plants at a time. Do not over-harvest a single plant.

When you notice a plant putting out buds, you have a choice. Cut off the stalks to redirect the plant’s energies to the leaves, or allow the buds to bloom and then harvest the flowers for use in the kitchen.

Likewise, you can also let the flowers wither into seed pods and then harvest the pods – both seeds and pods are edible.

Finally, you can simply allow some selected plants to flower and then run to seed so that they self-seed; thus, your supply of Rocket plants and leaves will continue automatically. 

In hot and dry weather do not let the soil dry out and stay dried out, otherwise the leaves will have a harsh, bitter taste.

close up of hands harvesting rocket
Rocket being Harvested

Common Diseases and Problems

Rocket varieties are generally disease-free.

The one pest you need to keep a watch for is flea beetle, particularly at the seedling and young plant stage.

If you anticipate an attack by flea beetles you can try to head off the problem by growing the plants under fleece. Otherwise release beneficial predators such as ladybugs and ground beetles. Another safe option is to spray organic products like Bug Clear for Fruit and Veg and Neudorff Bug Free.

Bolting is a particular problem with Salad Rocket though not with Wild Rocket. Follow the guidance in section How to Grow Rocket to avoid bolting. In addition be sure that plants are not too close and are about 15 centimetres apart or one to a pot.

Where to Get Rocket  

Regular Salad Rocket plants in pots are widely available at nurseries and garden centres. Wild Rocket is also available, just not as widely. Seed packets of each are also found at garden centres.

Seed packets of the more recent cultivars are available online at specialist seed merchants. You are sure to find a few pots of a couple of special varieties at a garden centre that has a good herb-and-veg focus.

yellow rucola flowers on white background
Wild Rocket Flowers are Very Pretty

Health Benefits

One could go on and on reciting the remarkable health benefits of this leafy green; we could say it is anti-cancer, promotes good vision, is heart healthy, and so on and so forth. Instead of going overboard we try to let the facts speak for themselves.

Rocket, especially Wild Rocket, contains significant amounts of glucosinolates and phenolics which are phytochemicals that are metabolised into indoles which are anti-cancer chemicals. Rocket is said to be particularly effective against bowel and colon cancer.

All varieties have a very high Aggregate Nutrient Density Index (ANDI); in other words, Rocket has an outstanding ratio of nutrients to calories. These nutrients include vitamins, minerals, and anti-oxidants with Salad Rocket edging Wild Rocket in vitamin content.

Rocket has Beta Carotene which is well known to be good for the eyes but on top of that it also contains lutein and zeaxanthin which combine with Beta Carotene and enhance its beneficial effects on vision.

Likewise, its combination of calcium and Vitamin K means that it aids in maintaining bone health.

In addition, this multivitamin tablet disguised as a leaf is packed with folate (Vitamin B9), calcium, magnesium, Vitamin C, Vitamin K, and has appreciable amounts of potassium, iron, phosphorous, and Omega-3. It is also brimful with anti-oxidants which combat free radical damage, and with anti-inflammatory compounds.

Rocket seeds are particularly rich in Omega-3, anti-oxidants, and anti-inflammatory compounds.

All said, Rocket is one of the most detoxifying foods you can eat.

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