How to Grow Rocket

Rocket is easy to grow and adds a lovely peppery flavour to salads. The more mature leaves can be lightly cooked, added to sauces, stir-fried or sautéed in olive oil. The flowers are also edible!

Sowing 

Rocket can be sown all year around in your Harvst S-Series but in the summer it will benefit from some shade as dry and hot conditions will cause it to bolt, flower, and set seed. As bolting equals the end of harvest, make sure to keep the soil moist at all times. 

Rocket has a long tap root which dislikes being disturbed. It is therefore best to sow the seeds either directly into the soil where it is going to grow or in multi-cell trays to avoid disturbing the roots when transplanting. You can also sow closely in a tray and harvest them as microgreens for a salad. 

For sowing in your Harvst, fill the multi-cell tray, tray or pot with general compost, water it and then scatter the seeds out. Cover with 0.5-1cm of compost and press down slightly to make sure that the seeds have good contact with the soil. How closely you space the seeds depends on the size of your cell trays and pots but you can always thin them out if too many germinate. Water again and keep the soil evenly moist until the seeds germinate because if they dry out they will most probably not germinate at all. This can be aided with a plastic dome over the tray but it is not a must.  However, as a general rule, the colder the soil the less moisture you want because a cold and very wet growing medium often results in rotten seeds!

If you want to sow directly outside, scatter the seeds thinly and cover with 1cm of soil. If sowing several rows, space them 15cm apart. Later, thin out the seedlings to 15cm apart. 

It is best to sow regularly for a constant supply of fresh leaves. Every two weeks if you can! Seeds can be sown until late in the season outside and all year around in your Harvst.

The ideal temperature for germination is 15-20°C  but it will germinate down to 5°C. Rocket may germinate within 7 days at the ideal temperature range. 

Plant care 

Keep the soil well watered throughout the growing season to avoid bolting and to ensure good flavour. However, it is important not to overwater as this can dilute the flavour. 

Rocket grows best in full sun apart from in the summer when it can benefit from some shade.

Growing options 

You can choose from one of the growing options below or do a combination of 2, 3 or 4! 

  1. Baby Leaves: Thin the seedlings to 10cm apart and then start harvesting directly from your tray when the leaves are big enough. If you pick one or two leaves of each plant from the outside, rather than the whole plant, it should keep on growing for a while and give you a few harvests! 
  2. Grow till maturity in your Harvst: When the seedlings have emerged, thin them to 15cm apart. This can be done by cutting the rejects with scissors (eat them in a salad!). The compost will only have enough nutrients for a few weeks so you will have to feed the plants with an organic fertiliser throughout the growing season. 
  3. Plant outside: When the seedlings have developed their true set of leaves (not the first set appearing but the second set) they can be transplanted out into your garden. Space them 15cm apart and be careful not to disturb the roots more than necessary. If you have problems with slugs, keep them in your Harvst a little longer till they’re about 10cm high. A bigger plant can resist a slug attack much better! When planting outside it is best to make sure that your soil is great before planting by adding well rotten manure or other organic material so that it’s full of nutrients for your plants. This will help to keep the moisture in the ground too. If your soil is not great you can feed the plants with an organic fertiliser throughout the growing season. When transplanting seedlings, ideally plant out early morning or evening and/or on an overcast day. Avoid planting at peak sun times or on windy days as this can cause sun or windburn which can lead to death! 
  4. Container Grown: Rocket grows well outside in containers but as they are heat-sensitive, move them into the shade on warm days and keep in mind that containers will warm quicker than garden soil in spring, so keep it well watered. Also, keep in mind that the compost will only have enough nutrients for a few weeks so you will have to feed the plants with an organic fertiliser throughout the growing season. 

Harvesting 

You can start harvesting the leaves from about four weeks after sowing and regular picking keeps the leaves young, tender and tasty. It is best to pick a few leaves from each plant because picking lots of leaves from one plant in one go will weaken its growth. 

Watch out! 

Flea beetles are the biggest problem leaving the leaves covered in small holes and damaged areas turning brown. They tend to be more of a problem in spring than autumn but should in any case not be a problem in your Harvst. When planting out seedlings are particularly susceptible. The best solution is to grow plants under horticultural fleece and keep the soil moist. Also keep the plants well fed to help the crop outgrow the pest. 

Pro Tip

As flower buds appear, pinch them out to prolong cropping and use them as a garnish for salads. If the plant has grown tall, leggy and full of flower stems try cutting it right back to 2cm. It will most probably produce a fresh crop of leaves.

Nerdy facts

The botanical name of Rocket is Eruca sativa but is also often called arugula, rucola, roquette. Rocket (Eruca sativa) is an annual plant whilst Wild Rocket (Diplotaxis tenuifolia) is a perennial plant. Wild Rocket is slower growing than the annual type and has a stronger flavour and richer nutrient content.These two are often mixed up and therefore causes a confusion whether Rocket is an annual or perennial.

Recommended Varieties

Here are two great varieties but there are many more fantastic varieties to choose from!

‘Rocket Apollo’ has large, rounded, tender leaves with an excellent peppery taste, but no bitterness.

‘Rocket Runaway’ has serrated leaves like a wild rocket and is fast and vigorous growing.