Hazelnut Male and Female Flowers: What Do They Look Like?

Hazelnut is a monoecious plant — it carries both male and female flowers on the same plant but in completely separate structures. Understanding how to identify each type and when they appear is essential for getting a nut crop. Many growers who have never spotted the female flowers assume their tree does not have them, when in fact they were there all along, just overlooked.

Male Flowers: The Catkins

Male hazelnut flowers form in clusters called catkins, which develop through autumn and become visible as small, tight cylinders hanging from the bare branches. By midwinter they begin to elongate, eventually reaching five to ten centimetres long. As temperatures rise in January and February they open fully, releasing clouds of fine yellow pollen on the wind. Catkins are unmistakable and decorative — they are the part of hazelnut flowering most people notice. A single established bush may carry several hundred catkins, producing billions of pollen grains.

Female Flowers: The Tiny Red Tufts

Female hazelnut flowers are far less conspicuous. They emerge from small buds on the shoot tips as tight clusters of thread-like red or pink stigmas — often described as looking like a tiny shaving brush or crimson paintbrush tip. Each bud is only two to four millimetres across at most. They appear at roughly the same time as the catkins elongate, typically January to March depending on variety and season. The stigmas are the pollen-receiving surfaces; once fertilised, each individual stigma can develop into a nut within the protective leafy husk.

Why Both Types Must Be Present and Synchronised

A hazelnut tree produces both male and female flowers, but hazelnut pollen cannot fertilise flowers on the same plant (a property called self-incompatibility). Pollen from a genetically different variety must arrive on the female stigmas during the brief period they are receptive — usually ten to fourteen days. If catkins from your tree shed pollen before the female flowers on a companion variety are open, or vice versa, pollination fails for that season. Matching variety pairs with overlapping flowering windows is therefore critical.

What Happens After Fertilisation

Fertilised female flowers develop slowly through spring and summer. The cluster of stigmas is replaced by a small green nutlet enclosed in a leafy, lobed involucre (husk). By August or September the husk dries and partially opens, and the nut inside turns from white to brown as it ripens. At this point it is ready to harvest. The whole process from fertilised flower to ripe nut takes roughly seven to eight months.

Checking Your Tree in January

The best time to confirm that your hazelnut has both flower types is during a dry spell in late January or February. Look for catkins that are starting to shed yellow pollen when tapped, and examine every shoot tip carefully with a magnifying glass for the tiny red stigma tufts. Their presence on the same plant is normal; their absence suggests the tree is very young, has been heavily pruned, or the buds were damaged by frost or pests.