Robinsons Mammoth Onion Improved Seeds – Exhibition Giant Variety - 100 Seeds

Robinsons Mammoth Onion Improved – Graded Seeds

Robinsons Mammoth Onion Improved is one of the most respected and historic exhibition onion varieties, renowned for its ability to produce exceptionally large, uniform bulbs with excellent vigour and sweetness. Through many years of careful selection and improvement, this strain has been refined to deliver outstanding consistency and performance for competitive growing.

When grown under good exhibition conditions, bulbs can exceed 6 lb in weight and reach up to 22 inches in circumference, while still maintaining a surprisingly sweet, mild flavour. This variety has an unrivalled pedigree, having won prizes consistently from the 1800s through to the present day, making it a firm favourite with serious exhibitors and vegetable show competitors.

Seeds supplied are graded seed, selected specifically for superior quality, vigour, and uniformity to give the best possible results for exhibition growing. Full growing instructions are included.

Key Features

• Historic and highly respected exhibition onion variety

• Capable of producing extremely large bulbs

• Sweet flavour despite impressive size

• Long and proven history of show success

• Carefully selected graded seed for improved vigour

• Excellent uniformity under exhibition conditions

• Supplied with growing instructions

• Seed count: approximately 100 graded seeds per pack

How to Grow Robinsons Mammoth Onion Improved

Sow seeds indoors from late winter to early spring using fine, free-draining seed compost. Sow seeds shallowly, lightly covering with compost, and keep evenly moist.

Germination typically occurs within 7–14 days. Once seedlings are established, pot on carefully to avoid any check in growth, as uninterrupted development is critical for producing exhibition-sized bulbs.

Plant out when conditions allow and all risk of frost has passed. Choose a full sun position with deep, fertile, well-prepared soil enriched with organic matter. Water and feed consistently throughout the growing season, and protect plants from stress for the best results.

Harvest in late summer to autumn once bulbs have fully developed.

Tip: Regular feeding, even watering, and careful handling are essential to achieving maximum bulb size.

Frequently Asked Questions

How many seeds are included in the pack?
Each pack contains approximately 100 high-quality graded seeds.

Is Robinsons Mammoth Onion Improved suitable for beginners?
This variety is best suited to experienced or serious growers, though beginners can grow it successfully with careful attention.

How big can the onions get?
Under good exhibition conditions, bulbs can exceed 6 lb and reach up to 22 inches in circumference.

Are these onions good for eating as well as showing?
Yes. Despite their size, the bulbs have a sweet, mild flavour and are excellent for culinary use.

What does “graded seed” mean?
Graded seed is selected for size, quality, and vigour, resulting in more uniform plants and better exhibition potential.

Perfect For

Exhibition and show growing

Competitive vegetable growers

Gardeners aiming for record-sized onions

Serious allotment holders and club competitors

Growers seeking a proven, historic variety