Why Does My Celeriac Bolt? (Answered)

Celeriac is an unusual vegetable that a surprising number of people have never heard of.  It grows underground like a turnip or swede but has an earthy, celery taste.  It is a pleasure to grow and eat and makes a great addition to stews and soups.

One of the downsides to growing celeriac is that it can bolt (which means run to seed prematurely) very easily.  In this article I try to answer the question Why does my celeriac bolt?

There are 3 main reasons celeriac will bolt (run to seed) prematurely and these are because the weather is too cold, because the soil is too wet or too dry and because the soil is too rich. Once celeriac has bolted it is no good to eat and should be dug up and added to the compost heap.

What Is ‘Bolting’

Before looking at why celeriac might bolt and how we can prevent it, let me first explain what bolting is.  When we say a vegetable has bolted, we mean it has decided to set seed prematurely.  Setting seed early is a plant deciding life is not good, it doesn’t think it will survive and it decides to throw all its energy into creating the next generation (seeds).

The reason plants bolt varies from species to species, but essentially it means things are not to the plants liking. 

Basically, the plants’ ideal growing conditions are not being met and the plant has decided the best thing to do is just create seeds.

Why Does Celeriac Bolt?

There are essentially 3 main reasons celeriac will run to seed prematurely.  These are;

  • Because the weather is too cold
  • Because the ground is too wet or too dry
  • Because the soil is too rich

Because the weather is too cold

Celeriac doesn’t like it when the temperature drops below 53°F (12°C) for more than 24 hours. Obviously, depending on where in the country you are will determine how likely it is to be that cold in any given month, so it is important to know your area.

For me, I like to start my celeriac off from seed and grow them undercover while the weather is still cool.  Once the season starts to warm up and I am sure the temperature won’t drop below 53°F I plant my celeriac outside on the plot.

If you have planted your celeriac outside and the weather forecast says the temperatures are going to drop, consider covering your celeriac with horticultural fleece. 

A light covering of fleece should be enough to keep the celeriac warm enough to stop it from bolting.

Because the ground is too dry or too wet

One of the most common reasons celeriac bolts is because the ground is too dry.  Celeriac, and its cousin celery, both need the ground to remain a little moist.  The good news is, it doesn’t matter if the surface is dry, it matters what is going on 2″ or 3″ (5cm or 7.5cm) deep.  Because celeriac roots are down quite far, that is where the moisture needs to be.

Knowing how much to water your celeriac can be tricky. I don’t tend to water mine unless we are having a really dry spell.  If you are not sure if your celeriac needs water, push your finger into the soil.  If it feels moist at about an inch down, it will be fine.  If it feels dry, give your celeriac some water.

Whilst celeriac doesn’t like the ground too dry, it doesn’t want it to be too wet either.  Celeriac may bolt or rot if it is continually wet.

Because the ground is too rich

Digging a little well rotten horse manure or homemade compost into the ground before transplanting your celeriac will help feed the plant as it grows.  If however, you dig copious amounts of well-rotted manure into the ground, your celeriac plants will put on lots of lush top growth and may well bolt due to excessive amounts of nitrogen in the soil.  

Only ever dig a small amount of manure or homemade compost into the ground, and always make sure it is well rotted, otherwise it may burn the celeriac roots.

Can You Eat Celeriac That Has Bolted?

When a celeriac bolts, it sends up a flower spike. As a result, the bulb becomes woody and tough to eat.

If you are lucky enough to catch the flower spike forming early, you may be able to cut it off, but the trouble is, there is a good chance the bulb will stop swelling, meaning you end up with a small, woody celeriac bulb which is no good to eat.

My Final Thoughts On ‘Why Does My Celeriac Bolt?’

Celeriac can be a fickle vegetable.  If the temperature drops too low or the soil is too wet or too dry or even if the soil is too rich, the plants may well send up a flower spike, making the bulb useless in the process.

Keeping celeriac happy is hard work, but well worth the effort if you manage to harvest the lovely, earthy, celery-tasting bulbs at the end of the season.

Arya Patel

Arya Patel is HomesteadSavvy.com’s fruit and vegetable editor. Arya has been homesteading for well over a decade and over that time she has grown countless varieties of fruits and vegetables. She aims to become completely self-sufficient over the next 5 years.
Fruit & Vegetable Editor