Celeriac is one of those vegetables that most gardeners overlook. But as it’s a delicious and nutritious addition to any meal, I would highly recommend growing it.
Although celeriac and celery are the same plant, their taste is very different. Celeriac, the root, tastes nutty and earthy, while celery doesn’t taste of much, but is rather mild.
Celeriac is an underrated vegetable. I love it mixed with potatoes as a mash, but celeriac is also great roasted or added to curries or sauces.
Nutritionally, this root veg is a real powerhouse. It’s high in fibre and contains lots of vitamins and minerals. Celeriac is the perfect addition for a healthy and tasty diet.
So let’s see how to grow celeriac from seed in the UK. But first…
What Celeriac Varieties To Try
Although there aren’t as many varieties around as for other veggies like tomatoes, you still have a choice. Here are the ones I would recommend you give a go.
Celeriac Mars
If you want to enjoy celeriac for a longer period, Mars is the variety for you. It stores really well, allowing you to eat this tasty and healthy veg over a longer period.
Celeriac Monarch
This variety has received the RHS Award of Garden Merit. The Monarch is ideal for eating raw, but can also be cooked. Why not try a celeriac coleslaw?
Celeriac Brilliant
If you want a rich flavour as well as the ability to store your celeriac over for months, this the variety for you. The Brilliant can be harvested all trough winter, making it a great winter veg.
Celeriac Monet
Unlike other varieties, this one is ready to harvest early. The Monet can be harvested as early as July until October. Ideal if you want your celeriac earlier. It’s also bolt resistant and can tolerate leaf spot.
If you want to benefit from the this nutritious root veg for a longer period of time, my recommendation would be to grow the Brilliant and the Monet to harvest from July until February.
How To Grow Celeriac From Seed In The UK Step-By-Step
Before we start, I have to say that growing celeriac from seed isn’t as simple as with other veggies. I have tried it several times before being successful.
That’s because the seeds and seedlings need the right conditions and care to germinate and thrive. But don’t be put off by that, it’s worth giving it a go. And if you follow these steps, you’re sure to be successful.
Step 1: Sowing Celeriac Seeds
While the plants are hardy once fully grown, their seeds and seedlings can’t stand frost. At the same time, celeriac has a long growing season, taking 6 months before you can harvest.
For these reasons, it’s vital to start off your celeriac sees indoors from March. Sow the seeds thinly in small pots and cover with a very thin layer of compost.
Celeriac seeds need around 15°C (59°F) to germinate, so a heated propagator works well. Alternatively, you can cover the pots with a plastic bag and leave in a warm location, but not too hot.
It can take up to 3 weeks for the seeds to germinate. I won’t lie to you, getting celeriac seeds to germinate isn’t easy. I have tried and failed, but I have also managed it.
It’s all about creating the right conditions.
Once the seedlings appear, move them to a bright windowsill, anywhere where temperatures won’t dip under 10°C (50°F). I made the mistake of moving the seedlings into my unheated polytunnel and it got too cold during the night and they perished.
Water your seedlings regularly, as they need a lot of water at all growing stages (Janik 2007)
If your seeds haven’t germinated, you can buy plug plants. The choice of varieties is smaller, but at least you can still enjoy homegrown celeriac. I have done that before when my seeds just didn’t want to germinate.
Step 2: Transplanting Celeriac Seedlings
Once your seedlings are big enough to handle without damaging then, pot them on into bigger pots, one seedling per container.
If you have used a seed tray, thin them out so you have one per module. Personally I prefer pots where I have one per pot, as it’s easier to plant them out.
Keep your seedlings well watered at all times and keeping them above 10°C. Even if they survive lower temperatures, it risks that they will bolt (setting seed early) later in their growing season.
Step 3: Preparing The Soil
Because celeriac needs constantly damp soil, the choice of final spot is important. Choose a bed that doesn’t dry out easily, ideally in a sunny or semi-shaded location.
The type of soil celeriac thrives is nutrient-rich and moisture retaining. To achieve this, dig in a good amount of organic matter, such as homemade compost, in preparation for planting out.
If you have a no-dig garden, add a good layer of compost or mulch and plant the celeriac plants straight into the mulch.
I found that the ideal spot is where the sun is on it in the morning but not in the afternoon. This will help with keeping the soil from drying out too much in the strong afternoon sun.
Step 4: Planting Out
Timing is crucial here. Young celeriac plants won’t survive frost, so wait until the risk of frost has past, which is in May or June, depending on where in the UK you are.
Make sure you harden off the celeriac plants first to ensure they have acclimatised to the conditions outdoors.
Space them 30cm (1ft) apart from each other to give then enough space to grow. I like to grow them with my leeks, as they need similar growing conditions.
To help with moisture retention, I would recommend mulching them once they have been planted out.
My favourite natural mulch for this situation is raw sheep’s wool. Not only does it help with moisture retention, slugs and snails don’t like it. And it will release nutrients into the soil over time.
Step 5: Caring For Your Celeriac Plants
There are two main things when it comes to taking care of your celeriac plants. The first is watering. As we have said, they need constantly damp soil, so water them regularly and don’t let the soil dry out.
During dry spells, it might be necessary to water more than once a day.
The second important thing is to remove any side shoots, like you would with tomato plants, and also the outer leaves as the plant grows. They will start to fall on the ground, which is when you should remove them.
This allows the crown to develop. Also remove any dry or brown leaves, and keep the bed as weed-free as possible.
Step 6: Harvesting Celeriac
Depending on which of the celeriac varieties you have chosen to grow, you can start harvesting from July, for the Monet, or September/October for most others.
Most celeriac varieties can be left in the ground over winter and harvested as you need them. To harvest celeriac, use a fork to carefully lift the plant out of the soil.
If you leave them over winter, you might want to add a layer of mulch, such as straw around them to keep the soil from freezing. Not that this will harm the celeriac, but it will make it easier to lift them out when you need them.
You can also harvest them all at once and store them, if the bed you planted them can get waterlogged in winter. They are best stored with their leaves snapped off and either buried in soil that doesn’t get waterlogged or in a container with compost left in a cool, dry place.
However, if you can, I would recommend leaving them in the ground until you need them, as this will allow them to develop a better flavour.
Pests And Diseases Affecting Celeriac
Celeriac might be tricky to germinate and grow on, but once it’s in the ground, it’s fairly easy going, as long as you ensure it has plenty of water.
There are a few pests and diseases to be aware of though.
Diseases
The main disease that might affect your celeriac plants is celery leaf spot. This fungal disease makes itself known by brown spots on the leaves and stems of the plant.
It thrives in warm and humid conditions and can stunt the growth of celeriac plants. Here’s how to minimise the risk of your plants getting infected:
- Space out plants correctly – giving the plants enough space between them to dry out foliage quickly and improve air circulation
- Water from underneath – by watering the soil directly you keep the foliage dry, reducing the risk of of the fungus to get a hold on the plants
- Weed regularly around celeriac – weeds can transmit the disease to your plants
If you spot any signs, brown spots on leaves and stem, remove the affected part and dispose of it in the garden waste bin, not your compost heap.
It might become possible that you have to remove the whole plant, depending on how bad the infection is, to prevent it from spreading to other plants.
Pests
Slugs and snails are a problem for many plants, including celeriac. They are particularly fond of young plants, where they can do damage. So protecting smaller celeriac plants from these slimy customers is key.
We don’t recommend using slug pallets, as these kill the slugs and snails, which are very important for your garden’s ecosystem. And they can also harm other wildlife, such as hedgehogs.
Instead, use these natural ways of keeping them away from your celeriac plants:
- Mulch area with raw sheep’s wool – not only will this help with moisture retention, but also keep slugs and snails away
- Use copper rings – slugs and snails don’t like copper so won’t cross it to get to your plants
- Pick them off – this can reduce the amount of slimy creatures nibbling at your plants
- Encourage beneficial wildlife – beetles, hedgehogs, and birds eat slugs and snails
Another pest that might have it in for your celeriac is the celery leaf mining fly, sometimes just called the celery fly.
The female flies lay eggs on the leaves of the celeriac. The resulting larvae will then bore into the leaves and eat them from inside. The first sign will be large light green patches, which will turn brown and dry out.
To prevent these maggots from becoming a problem, you have to prevent the female flies from laying their eggs on the foliage. This is best done by covering the plants with insect mesh.
Crop rotation is also vital, as the larvae can overwinter in the soil, so if celeriac or plants in the same family are planted in the same spot the following year, the flies will lay their eggs on the new plants.
If you see any sign, remove the affected leaves and dispose of them in the garden waste bin. This will minimise the damage.
Encouraging their natural predators, such as some parasitic wasps and birds, like blue tits, can also help to keep the population down so they won’t cause too much damage.
So here you go, this is how to grow celeriac from seed in the UK. It’s not the easiest veg to grow, but totally worth it. So give it a go this year. Happy Growing!
