3 For 2 on Christmas Cropping Potatoes

Enter code XMAPOT at checkout for offer to apply. Hurry! Whilst Stocks Last. Click here to view all varieties on offer.

Buy 1 Get 1 Half Price

When you add this variety to basket. Discount automatically applies at checkout.

Buy 2 Save £10.00 on This Variety

Use discount code POTM06 at checkout. Hurry While Stocks Last!

3 for 2 on Same Variety 9cm Plants

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Save up to £15 on Bird Care

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Free Delivery When You Spend £40 on Seed Only Orders

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Get this item FREE when you spend £10.

Add this product to your basket PLUS a further £10 worth of any products. The free item will be automatically discounted during check out. Hurry! Only available for the first 2,023 orders - ends midnight Monday.

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Heat Prepared Onion Duo

Marshalls Garden

Catalogue Code: 10406199

RHS Award of Garden Merit
Sale price

Out of Season

Regular price £4.98
Super value duo of Heat prepared Onions that have been specifically heat -treated for 20 weeks to minimise bolting, where the onion tries to flower too early and therefore reduces onion size. Heat preparation will also extend the growth period on the onions which leads to a much greater yield. Duo contains 1 pack on Heat prepared onion Centurion and 1 pack of Heat prepared Onion Rumba.

Key Features

  • Bolt resistant
  • Prefers full sun

Pack Contents: Approx 65-75 sets of each variety


  • Bolt resistant offering more success
  • Royal horticultural Society Award of Garden Merit
  • Copes well with less-than-great summer weather
  • Bulbs store well for several months

Onion Centurion - This award-winning onion matures early even in less-than-great summers, producing a heavy crop of round bulbs with golden skins, crisp flesh and top-quality flavour. A holder of the prestigious RHS Award of Garden Merit, Onion ‘Centurion’ is easy to grow and stores well for a long period.

Onion Rumba - A top-performing main crop variety that’s ideal for growing in the UK. Rumba produces high yields of large, uniform, round onions with a sweet flavour, making it ideal for eating raw in salads as well as cooking.

Heat-treated over a period of time before arriving to you, your sets are less prone to bolting and going to seed, which in turn affects the quality of the bulbs.

How you will receive your plants:

Selected by our team of experts and sent from our nursery, you will receive your onion sets in a breathable net bag. This keeps them together in a pack that is nice and airy – perfect to keep them healthy while in transit.

Can’t plant straight away?

Keep your onion sets in a cool, dark, and dry place and preferably hanging on a hook so that air can get to the bulbs at all angles. Ideally, you should aim to plant them within a week of receiving them, but if this is not possible, store them in a cool, dark place until you are ready to plant them.

Planting tips and hints:

A couple of weeks before planting, dig over the soil with a shovel to clear weeds. Rake in a general purpose fertiliser.

To plant your sets, push the sets into the soil with the pointed end upwards. Leave 5-10cm between sets. Cover the area with horticultural fleece to protect the young plants from birds.

Water regularly in dry periods, and weed regularly. Stop watering once the leaves start to yellow.

Harvest bulbs once the leaves have turned yellow and flopped over. Use a fork to carefully lift the bulbs.

Click here to view our full Onion and Shallot Growing Guide.

Growing Calendar

J Jan F Feb M Mar A Apr M May J June J Jul A Aug S Sep O Oct N Nov D Dec
Plant Outdoors


We know how important your garden is to you. We've listened to our customers and introduced a new improved speedy delivery service, meaning Express delivery comes as standard.

*Orders to Northern Ireland have an automatic additional £3.00 delivery surcharge applied at checkout. 

Order TypeDelivery ChargeDelivery Charge
Seed only order£2.99If you purchase any other items you'll be charged the standard delivery rate of £5.99
Plants, bulbs & gardening accessories£5.99If we need to split your order into separate deliveries we'll only charge one delivery fee
Extra large or long plants & heavy items£9.99These are clearly displayed at check-out
Compost (and any other large or heavy items)£5.99

These items are subject to a delivery multiplier where orders containing 3 or 4 items will be subject to an additional £5.99 for every further 2 items added. This is automatically applied at check-out:

  • 1 - 2 bags £5.99
  • 3 - 4 bags £11.98
  • 5 - 6 bags £17.97
  • 7 - 8 bags £23.96
  • 9 - 10 bags £29.95

If you'd like more than 10 bags of compost please call our Customer Service team who can arrange for a bespoke competitive quote on 01480 774555 (standard network charges apply)

For more detail on specific delivery queries and compost delivery please click here

Delivery to outside of Great Britain

We regret we are unable to deliver any items outside of some Great Britain delivery addresses. This includes Europe, Channel Islands, Republic of Ireland, USA and Rest of World. We will update our website if this changes. 

We now deliver to Northern Ireland, additional delivery surcharges automatically apply at checkout. 

For more information about our deliveries please click here.