Arugula is a cold-weather crop that is incredibly fast-growing, hence the name “rocket” salad. It’s one of our favorite leafy greens to throw in our salads and pestos.
As we live in a mountain area and garden in zone 6b, we have a short spring and cold-hardy crops only do well for about a month. Arugula is no exception, frequently bolting by the time we want to enjoy our second sowing.
There is no way to prevent arugula from bolting – arugula going to seed is the plant’s natural course. But you can try a few tricks to slow it down: plant arugula in the shade and ensure that the soil is moist. If you have a short spring, focus on growing arugula as a fall crop.
A lot of first-time gardeners see their cool-weather vegetables, like arugula, bolting and feel like they’ve done something wrong. But with such quick-maturing crops, bolting is inevitable.
All plants go to seed. Tomatoes, peppers, aubergines, and many other vegetables go to flower, and we don’t mind. In fact, it’s required of them to do this so that they can reach maturity and give us fruit.
So why should arugula be any different? Bolting in cold weather crops means going to flower and then seeding, and it’s controlled by several factors.
Why does arugula go to seed?
When arugula bolts, it grows a vigorous stem that will produce flowers and seeds in an effort to reproduce. We want this process to occur as late as possible because as soon as a plant bolts, it diverts all its energy into this new growth instead of continuing its leaf production.
For leafy greens, this means that the leaves will get bitter, and in many cases, inedible because of the taste. Don’t worry, though – they’re not poisonous.
In crops like cold-hardy greens, lettuce, basil, beetroot, spinach, celery, brassicas, leek, and onion, bolting is something to be avoided as it leads to altered taste and texture in the plant. It’s best to harvest these vegetables before they go to seed.
Bolting is induced by a hormone of the gibberellin family and is caused by a number of factors:
- High temperatures;
- Lack of water or minerals;
- Alternating low or high temperatures;
- Plant stress: it goes to seed before it dies.
How to extend your arugula harvest
Sometimes, there’s just not much you can do about your arugula bolting. If the weather suddenly warms up or you struggle to provide enough water for your plants, leafy greens like arugula, spinach, and lettuce will most likely suffer.
The best thing you can do to ensure an excellent arugula harvest is to respect the plant’s natural timing. You can figure out the best timing for arugula by knowing your climate well and leveraging the best temperature and time of the year.
Arugula growing temperature
Arugula grows best in between the 45° to 65°F (10° to 18°C) temperature range. It takes about 40 days to mature, so it’s best to sow it in early spring so that it can crop in late spring.
As an alternative, you can sow it during autumn when the weather cools down, so you can harvest it during late autumn or winter (if you have a mild winter, or if you protect it with cold frames). In my climate I find late summer and early fall sowings work best.
Best growing conditions for arugula
The other two factors you need to consider when sowing arugula are heat and humidity. If you sow arugula in an area that’s more shaded, it will naturally last longer than if you sowed it in the sunniest spot of the garden.
Another smart way to provide shade for your cold-weather vegetables is planting them as part of a polyculture so that they become shaded by taller plants, such as corn, peppers, beans, tomatoes, etc.
- Tip: Create temporary shade in a sunny location by suspending shade cloth above your arugula plants to extend the harvest.
Like any other leafy green, arugula has shallow roots and needs a lot of humidity to thrive. To ensure that your arugula is off to a great start, make sure that your topsoil is rich in nutrients and holds water well.
You can accomplish this by spreading a thick layer of organic compost in early spring. For dry climates, even add a layer of mulch, such as straw or woodchips.
Finally, if your arugula does indeed bolt, you can slow it down a little bit by pinching the flowers off. Unlike basil, this will not encourage the plant to produce more leaves. However, it will give you a bit more time before the leaves become too bitter.
In warm weather, arugula bolts and gets eaten by pests
In my experience, arugula works best if directly sown and harvested with a cut-and-come-again method. For a more continuous harvest, try sowing arugula seeds at 2-3 week intervals. In spring, this will give us about two to three yields (about a month) before it goes to seed and the warm weather starts encouraging pests like flea beetle.
You can keep flea beetles away by using floating row covers, but from what I’ve learned, once flea beetles become active, it’s tough to get rid of them, and they wreak havoc on cold-weather crops and seedlings.
To avoid damage from heat-loving pests and a short season due to bolting, try sowing arugula at the beginning of autumn. You can protect it from light frosts as it reaches maturity by covering it with cold frames.
When trying to direct sow it in early autumn, the biggest problem is patchy germination. Just like lettuce, you can also plant arugula from modules, which can significantly extend the season. Sow arugula in modules inside a greenhouse in early spring or sow it under grow lights in autumn, so you can plant it outside when the weather cools down.
Arugula doesn’t require much sun, and it can even be sown as an indoor crop on a windowsill, as it doesn’t need a lot of soil depth.
My arugula has bolted – now what?
When arugula bolts, don’t throw it in the compost just yet, at least not all of it. Its leaves will intensify in spiciness, but you can still enjoy them for a while. If you don’t have enough space in your garden and intend to succession plant another crop, you can get rid of most of your arugula. But I challenge you to keep a plant or two as a delicacy.
As bolting takes its natural course, having a varied display of flowers in your garden will attract beneficial insects and pollinators. If you allow arugula to go to seed completely, it will self sow in your garden and become a tasty “weed.” You may notice a few volunteer plants sprouting every now and then. They aren’t invasive, so there’s no risk in allowing this plant to reach maturity.
Can you eat arugula seeds?
The flowering stems produce delicate white blossoms, which you can enjoy in salads for their taste and decoration purposes. The immature seed pods can also be thrown in salads and are similar to snow peas or radish seed pods, with a strong spicy radish taste.
Very few people know that arugula dry seeds that have reached maturity are edible too. You can grind arugula seeds up and throw them in salads, stews, or use them to season meat and fish. They are especially popular in Arabic, Italian and French cuisine, as they give a spicy kick to any recipe they’re added to.
There’s really no right or wrong way to grow this lovely spicy green, filled with flavor and personality. Your microclimate will be unique, and the best way to optimize your harvest is by trial and error. It’s important that you don’t get discouraged if your arugula quickly goes to seed. Instead, learn from what has happened and try to sow it at a different time next year.
If your sowing dates are on point, assess whether your soil has enough nutrients to support intensive gardening. If you suspect water is the issue, try drip irrigation as a source of constant humidity.
It would be a shame to give up growing this delicious green just because it has a short growing season. Arugula provides a whole array of vitamins – a lot of vitamin C, A, and K, and minerals like calcium, magnesium, potassium, iron, and zinc. Don’t miss out on all the health benefits this plant provides!