Fertilising guide

How to fertilise Hazel 'Red Filbert' (Corylus avellana 'Purpurea')— schedule & NPK

Also called purple-leaf hazel, red filbert, ornamental hazel.

More about hazel 'red filbert'

About Hazel 'Red Filbert'

Corylus avellana 'Purpurea' · also called purple-leaf hazel, red filbert · edible

This purple-leaved hazel is an ornamental, edible-nut form of common hazel with deep red-purple spring foliage, purplish catkins and reddish husks. Hardy, easy and shade-tolerant, it suits hedges, woodland edges and mixed borders. Foliage colour holds best in full sun; nut yields are modest compared with dedicated cobnut cultivars.

Growth habit: Deciduous, suckering, multi-stemmed shrub or small tree, often coppiced or grown as a hedge.

What fertiliser hazel 'red filbert' actually wants — and why

Hazel 'Red Filbert' feeds in two distinct phases — balanced to build the plant, then high-potassium the moment flowering starts to set and fill a heavy crop.

For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for hazel 'red filbert': match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.

How often to feed hazel 'red filbert', and which months

Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For hazel 'red filbert':

Generally needs little feeding in reasonable soil; an annual spring mulch of compost or a light balanced feed maintains vigour. Avoid excess nitrogen, which promotes leafy growth over catkins and nuts. So: a balanced feed or compost at planting, then a high-potash liquid every 1-2 weeks from first flower through harvest across the main season (spring through early autumn).

The dormant-season rule matters more than the exact interval: skip feeding entirely when hazel 'red filbert' is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.

What strength to mix for hazel 'red filbert'

Follow the crop-feed label rate for hazel 'red filbert' — these are calibrated for hungry vegetables. Consistency through fruiting matters more than strength; erratic feeding causes problems like blossom-end rot.

Feeding always goes onto already-damp soil, never dry roots — water hazel 'red filbert' first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the hazel 'red filbert' watering schedule.

Signs you are over-feeding hazel 'red filbert'

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for hazel 'red filbert':

Vigorous dark-green leafy growth but few flowers or fruit (excess nitrogen).
Lush foliage hiding the crop; soft growth prone to pests and disease.
Salt crust on the soil and scorched leaf edges in containers.

Signs you are under-feeding hazel 'red filbert'

Pale, yellowing lower leaves and stunted growth.
Small fruit, poor set, and a quickly exhausted plant.
Blossom-end rot and weak cropping from erratic or insufficient feeding.

If the symptoms point at watering, light or roots rather than nutrition, the full hazel 'red filbert' care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

In containers, fertiliser salts build up fast — water hazel 'red filbert' thoroughly so excess drains from the base each time, and flush pots with plain water every few weeks to prevent a damaging salt build-up.

Organic vs synthetic feeds for hazel 'red filbert'

Organic options

Garden compost or well-rotted manure dug in before planting, plus a liquid comfrey or seaweed feed once fruiting starts. UK: comfrey feed or organic Tomorite; US: Espoma Tomato-tone or Neptune's Harvest. Builds soil and feeds in one.

Synthetic / liquid feeds

A balanced feed at planting then a high-potash tomato feed in fruiting — UK: Growmore at planting then Tomorite (Levington) or Phostrogen; US: a balanced 10-10-10 then Miracle-Gro Tomato or a bloom booster.

Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.

Fertilising hazel 'red filbert' — frequently asked questions

What fertiliser does hazel 'red filbert' need?

Balanced (even N-P-K) at planting for roots and frame, then switch to a high-potassium ("high-potash") tomato-style feed once the first flowers open — potassium is what sizes and ripens fruit, not nitrogen. Hazel 'Red Filbert' feeds in two distinct phases — balanced to build the plant, then high-potassium the moment flowering starts to set and fill a heavy crop.

How often should I feed hazel 'red filbert'?

Generally needs little feeding in reasonable soil; an annual spring mulch of compost or a light balanced feed maintains vigour. Avoid excess nitrogen, which promotes leafy growth over catkins and nuts. Generally needs little feeding in reasonable soil; an annual spring mulch of compost or a light balanced feed maintains vigour. Avoid excess nitrogen, which promotes leafy growth over catkins and nuts. So: a balanced feed or compost at planting, then a high-potash liquid every 1-2 weeks from first flower through harvest across the main season (spring through early autumn).

What strength of feed for hazel 'red filbert'?

What does over-feeding hazel 'red filbert' look like?

Vigorous dark-green leafy growth but few flowers or fruit (excess nitrogen). Lush foliage hiding the crop; soft growth prone to pests and disease. Salt crust on the soil and scorched leaf edges in containers. Staying on a high-nitrogen feed once hazel 'red filbert' starts flowering is the classic error — you get a huge leafy plant and a disappointing crop. Switch to high-potash the moment flowers appear.

Should I flush the soil of hazel 'red filbert'?