Mr VegHead says...

Vegetable musings from Sea Spring Seeds

Bolting observations in Oriental salads trial

Bolting is the endgame

For gardeners cultivating leafy greens, bolting is a catastrophic event that signals the end of leaf production and the beginning of reproductive growth. It is a gradual process that proceeds in stages, beginning with the elongation of the bases of the plants. Eventually a stem emerges from the centre of each plant and progresses through reproduction in an orderly sequence that starts with buds, that blossom into flowers that finally yield seeds.

Red Knight Mizuna with a bolted stem.

Red Knight Mizuna with a flowering bolted stem.

Yukina Savoy with a bolted stem.

Yukina Savoy tatsoi with an elongated ‘bolted’ stem.

For more information about bolting see our website.

Our trial observations

Though bolting is the inevitable endgame in the natural cycle of leafy vegetables, it can be delayed by the judicious selection of varieties. Over the years, we have grown dozens of leafy greens side-by-side, enabling us to evaluate them for bolt resistance ­– and the differences we’ve noted have been astounding.

Oriental salads growing overwinter in a polytunnel.

Our overwintered Oriental salads in polytunnel in January. They were sown into modules in early October, and transplanted into the tunnel when the tomatoes were cleared in November.

Take, for example, the brassicas we’ve grown this winter, which for the most part were varieties from Sea Spring Seeds’ catalogue. Sown in October of 2016, they were grown in a polytunnel and evaluated for bolting on 26 February, 2017. Each variety was rated on a scale that ranged from 1 (no bolting noticed) to 5 (most advanced). The results were the following:


Variety                                                    Rating                                Comment


Joi Choi (pak choi)                                     1.0                                  No bolting
Yang Qing Choi (pak choi)

Broadleaf mizuna                                       1.5                                  Early hints of elongation

Green Spray (mibuna)                                2.0                                 Elongation just beginning
Red Giant (mustard)
Torasan (komatsuna)

Red Thrills (mustard)                                  3.0                                  All plants elongated
Ruby Streaks (mustard)

Apex (Chinese cabbage)                            3.5                                  Some buds visible, but no open flowers
Yukina Savoy (tatsoi)

Red Knight (mizuna)                                 4.0                                   Some open flowers

Salad Rocket                                             5.0                                   Almost all plants have open flowers



We made the general observation that its onset of bolting seemed to be earlier than in past years. Otherwise, regarding the relative differences between varieties there were no surprises: Joi Choi and Yang Qing Choi were the most bolt resistant, salad rocket was the least, and everything else fell somewhere in between.

Yang Qing Choi, a green stemmed pak choi.

Yang Qing Choi, a green stemmed pak choi.

Joi Choi, a white stemmed pak choi

Joi Choi, a white stemmed pak choi. As usual Joi Choi is the most bolt resistant

Are they the same variety?

One unexpected result was the striking similarities between the mustard varieties ‘Ruby Streaks’ and ‘Red Thrills’. To our eyes, they both look exactly the same: deeply cut leaves that are deep red.

Mustard var. Red Frills

Mustard var. Red Frills. We think it look (is?) exactly the same as Ruby Streaks

Mustard var. Ruby Streaks

Mustard var. Ruby Streaks. This variety cannot be recognised apart from Red Frills.

The plants were also at the same stage of bolting during the evaluation, leading us to believe that, despite the different names, they may be the same variety. We sell Red Frills but not Ruby Streaks, and are concerned with this state of affairs. It is certainly an issue we will be pursuing with our supplier.

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On 3 March, we again evaluated the leafy greens for bolting. We discovered that plants of Yang Qing Choi were just beginning to elongate, while those of Joi Choi still showed no signs of going to seed. This just confirms what we observed every year in our undercover overwinter trials, i.e.  Joi Choi is the most bolt-resistant variety of Oriental salad that we know.