How to Prevent Bolting in Lettuce, Spinach, and Coriander

There’s nothing quite like the satisfaction of harvesting crisp lettuce leaves, tender baby spinach, and vibrant bunches of coriander. But just when everything’s looking lush then bam! the plants shoot skywards, flowers appear, and the flavour turns bitter overnight. That, friends, is bolting. And it can ruin an entire bed of greens in days.

Bolting is a natural part of a plant’s life cycle, but when it comes too early, it cuts short our harvest window. The good news? With a few simple changes to how we grow, we can delay bolting and keep those leafy crops thriving for far longer.

Let’s dive into what causes it and how we can stop it in its tracks.

What Is Bolting?

Bolting is when a plant stops producing leaves and starts producing flowers and seeds. For lettuce, spinach, and coriander, this usually means:

• A sudden upward shoot from the centre
  
• Smaller, tougher, or bitter-tasting leaves
  
• Rapid decline in harvest quality

It’s the plant’s way of saying, “I’m done growing, time to reproduce.” But with a few strategic moves, we can convince it to stick around a bit longer.

What Causes Bolting?

Bolting is usually triggered by environmental stress. The main culprits include:

• Heat and long daylight hours – common in midsummer
  
• Drought stress – inconsistent or insufficient watering
  
• Overcrowding or root disturbance – especially during transplanting
  
• Genetics – some varieties are just more bolt-prone than others

So the aim is to reduce stress and provide ideal growing conditions.

How to Prevent Bolting in Leafy Greens

Sow at the Right Time

Lettuce, spinach, and coriander are all cool-season crops.

• Sow early in spring and again late summer to early autumn for best results.
  
• Avoid sowing in the peak of summer unless growing in partial shade.

Provide Shade and Cool Conditions

If growing in warmer weather:

• Use shade cloth, plant next to taller crops, or grow on the north side of structures.
  
• Water early in the morning to reduce heat stress and avoid evaporation.

Water Consistently

Dry soil stresses plants and speeds up the urge to bolt.

• Keep the soil evenly moist but not soggy.
  
• Mulch well to conserve moisture and regulate soil temperature.

Harvest Early and Often

Regular picking encourages plants to keep producing leaves instead of switching to reproduction.

• For lettuce and spinach, use the “cut and come again” method.
  
• With coriander, snip the stems above the lowest leaves and never let it flower.

Succession Sow

Even with the best care, some bolting is inevitable in hot weather.

• Sow small batches every 2-3 weeks to ensure a continuous supply.
  
• Mix heat-lovers into summer salads as backup greens.

Can You Save a Bolting Plant?

Once a plant starts bolting, there’s no reversing it, but not all is lost.

• Lettuce: Harvest immediately and compost the rest.
  
• Spinach: Leaves will turn bitter quickly, so pick what you can.
  
• Coriander: Let it flower, pollinators love it and harvest the seeds for use as spice or next year’s sowing.

Bolting might be a fact of life in the veg patch, but it doesn’t have to ruin your leafy green harvest. By choosing the right varieties, sowing smart, and protecting plants from stress, you can keep your lettuce, spinach, and coriander lush and productive for much longer. It’s all about working with the seasons, not against them.