Cobnut vs Filbert: What Is the Actual Difference?

The terms cobnut, filbert, and hazelnut are used loosely and often interchangeably, which causes confusion for gardeners and shoppers alike. There are real botanical distinctions between them, but in everyday garden use the lines are blurred further by centuries of hybridisation and varied regional naming conventions. Here is a practical guide to what the terms mean and why it matters for what you grow.

The Botanical Distinction

The formal distinction is species-based. Hazelnut and cobnut refer primarily to Corylus avellana, the common hazelnut native to Europe. Filbert refers to Corylus maxima, a closely related species native to southeastern Europe. The key visual difference is the husk (involucre): on a cobnut (C. avellana) the husk is shorter than the nut, exposing the top portion of the shell; on a true filbert (C. maxima) the husk fully encloses and extends beyond the nut, forming a distinctive tubular structure. In practice, many commercial varieties are hybrids of both species and do not fit neatly into either category.

What Cobnut Means in Practice

In Britain, "cobnut" is the term traditionally used for cultivated hazelnut grown specifically for fruit production — particularly the varieties grown in the traditional cobnut plats (orchards) of Kent. Well-known cobnut varieties include 'Cosford Cob', 'Webb's Prize Cob', 'Pearson's Prolific', and 'Nottingham Cob'. These are all selections of Corylus avellana or hybrids. The term cobnut is effectively a horticultural rather than strictly botanical category: a cultivated hazelnut variety grown for its nuts.

What Filbert Means in Practice

Filbert in the UK usually refers specifically to Corylus maxima varieties, of which 'Kentish Cob' (sometimes called 'Lambert's Filbert') is the most commonly grown. The name is slightly misleading because 'Kentish Cob' is actually classified as C. maxima despite having "cob" in its name. Continental European filbert varieties such as 'Gunslebert', 'Merveille de Bollwiller', and 'Fertile de Coutard' are also C. maxima or hybrids grown widely as commercial crop hazelnuts across France, Spain, Italy, and Turkey.

Does the Difference Matter for Gardeners?

For practical growing purposes, the distinction matters mainly for pollination pairing. Corylus avellana and C. maxima varieties are cross-fertile with each other, so a cobnut and a filbert can pollinate each other effectively. What matters is choosing named varieties with overlapping flowering windows rather than worrying about species classification. Flavour, nut size, vigour, and disease resistance vary more by individual variety than by species.

Hazelnut as the Catch-All Term

In everyday language and in supermarkets, "hazelnut" is used as the generic term covering both cobnuts and filberts. When you buy hazelnut pieces for baking or hazelnut spread, the raw material is most likely a large-kernelled commercial filbert variety. When you buy fresh cobnuts in their husks at a farmers' market in September, you are buying a cultivated C. avellana or hybrid. All are Corylus, all taste broadly similar, and all are grown in essentially the same way.