Do You Need To Thin Arugula (Rocket)?

This post contains affiliate links. As an Amazon Associate TinyGardenHabit.com earns from qualifying purchases.

Arugula (or rocket) is one of the easiest greens you can grow if you’re blessed with long springs and autumns. Sprinkle the seeds in rows, like you would with carrots, or sow arugula in a container and you’ll get a harvest in as little as 40 days.

When sowing those tiny arugula seeds, it’s hard to control the plant density you’ll end up with. Once those tiny seeds sprout, it might seem like they’re too close together. Some gardeners proceed to thin their arugula patch. But is that really necessary?

Arugula (rocket) doesn’t need to be thinned when grown close together because the taller arugula plants will naturally inhibit the younger seedlings from developing. This natural selection is great for shading the soil, suppressing weeds, and maximizing growing space through high-density planting.

While root crops like carrots or radishes get stunted if they’re not thinned in time, arugula is a green, and it does just fine packed together, especially when harvested through the “cut-and-come-again” method. Read on if you want to learn how to get a continuous harvest of this spicy herb.

Is thinning your arugula really necessary?

Thinning arugula isn’t necessary because of the way nature has evolved to handle plant competition. However, there are a few things you should know about growing arugula in this way.

Firstly, since it’s such a short-season crop (mainly because springs tend to be short nowadays), it’s best to sow arugula as early as possible. I sow it in early March and sometimes protect it with a layer of horticultural fleece, when the temperatures get too low, to speed up germination. Arugula tends to sprout in about 7+ days.

When sowing arugula, you don’t need to think about how many seeds I’m dropping in the ground, but you do need to space your rows properly. I sow my arugula in rows that are 4 inches apart.

As the arugula seeds inside the rows will begin to sprout, they will self-cull. Culling is essentially nature’s process of thinning in the plant world – survival of the fittest. This way, you get the ideal spacing in between arugula plants without doing anything.

Another advantage to not thinning your arugula is support. Your arugula plants will grow to be self-supporting, because they will lean on each other and grow to point upwards, instead of spreading out. This also helps you out with harvest – it’s much easier to cut leaves that are upright instead of sprawling on the ground.

You can also forget about weeding with densely sown arugula. There’s no room for weeds to grow inside the rows, and the leaves form a canopy in between rows, touching each other, which shades the ground and suppresses weed growth.

If you’re worried about competition and stunted growth, know that this is only a problem for root crops. Arugula roots can sense when they’re touching each other, so they start to grow downwards, where they can have access to water and nutrients with less competition.

This is why it’s essential that your soil is loose and very very fertile. In fact, you need to have highly fertile soil for any high-density planting, or you won’t succeed. Amend your soil with plenty of compost, minerals, worm castings, and organic fertilizers of your choosing.

Lastly, forget about transplanting arugula seedlings in your raised bed. It’s just not space-efficient. No matter how tight you pack them in, you won’t reach the density of directly sown arugula, and you’ll get less product as a result.

How do you pick arugula so that it keeps growing?

Harvesting arugula with the “cut-and-come-again” method is a breeze. This method is just what it sounds like – you take a pair of scissors, trim the leaves off one segment of your row, and once a few weeks have passed you can harvest from that area again.

Meanwhile, you can move on to the rest of the row and cut as much arugula as you need for one meal. Make sure to leave at least two inches of growth above the soil’s surface, to preserve at least a quarter of the plant.

Because arugula plants are growing so closely together, after harvesting, you’ll notice young leaves in between the cut stems. That’s where new growth will happen. You might also get a few weeds in between every now and then, so keep an eye out for that.

If cut and not pulled from the ground, arugula will grow back after being cut back 2 to 3 times. Usually, it’s the bolting that turns it bitter and inedible and not the repeated harvest.

Arugula and succession sowing

Since arugula has such a short growing season, one row of it won’t last you for very long until it goes to seed. So how do you ensure a continuous supply, at least while the weather allows it?

The answer is succession sowing. I like to sow a fresh row of arugula every week, 3 to 4 rows in total, and choose a shaded part of my garden for the final rows so that when that late spring sun hits, my arugula doesn’t immediately bolt.

Once the weather cools down and autumn temperatures allow for this plant to thrive again, you can proceed to sow new rows in succession to ensure a continuous arugula harvest.

Lastly, if you’re a big arugula fan, you can grow it indoors any time of the year under grow lights (10 hours of light per day works best). You won’t get it in industrial amounts, but it’s still a nice green to have at all times.

Arugula bolting – should you pinch the flowers off?

If we won’t be thinning, let’s talk about pinching. Once the weather heats up, this cool-weather crop will immediately bolt – or go to seed. You can stall this process for a little bit and pinch the flowers off. This will give you a few more days of edible arugula.

Unfortunately, there’s really no way to stop this process, so once arugula has bolted, it’s game over. Read this article I’ve written on bolting to learn why this happens.

Conclusion

Arugula is a delicious spicy herb packed with nutrients. Rich in chlorophyll and cancer-fighting properties, arugula deserves to be a staple in your diet while it’s in season. It’s so easy to grow and so low maintenance that its only disadvantage is that it doesn’t last long enough. I hope you decide to include arugula in your growing plan this year.