What is hilling up fennel, and what is it for
Hilling up consists of drawing soil around the base of the plant until the bulb is covered, promoting blanching and the white color required by the market.
If necessary, top-dressing fertilizer can also be applied during the same operation, optimizing field passes.
Why hill up fennel
Hilling up can offer several benefits during the crop cycle:
Blanching of the fennel bulb
covering it with soil limits exposure to light and helps maintain its characteristic white color
Looser soil
shallow cultivation facilitates bulb development in less compact soil
Protection from cold
In winter crops, the soil mounded around the base can help protect the plant from low temperatures
Weed control
Passing between the rows helps control weeds and reduce competition for water and nutrients
Surface water management
Under suitable conditions, soil shaping can promote water drainage and help prevent waterlogging
How to hill up fennel correctly
Passing between the rows
using a furrower or ridger
Moving the soil
toward the base of the plants
Covering the fennel bulb
without reaching the leaf stalks
Also read our article on fennel planting techniques and plant density.
Pay attention to soil conditions
It is best to wait until the soil returns to a workable moisture condition, meaning it has the right moisture level for cultivation.
Mounding excessively wet soil around the bulb can create favorable conditions for the development of rot and fungal or bacterial diseases.
When to hill up fennel
In general, two main strategies can be adopted:
Repeated hilling every 15–20 days
Hilling is carried out at regular intervals throughout the bulb’s growth period, supporting the plant at each stage.
Each successive hilling gradually covers the bulb as it develops.
This helps produce a uniformly white, compact bulb of optimal size.
Single hilling before harvest
A single hilling operation 15 days before harvest can still provide sufficient blanching of the bulb for marketability.
It is less effective than repeated hilling throughout the growth cycle, but significantly better than not hilling at all.
When to carry out the first hilling
The exact timing should therefore be adapted to the fennel variety and the crop cycle.
For more information, read the article on Fennel cultivation: varieties and crop cycle.
Mistakes to avoid when hilling fennel
Soil that is too wet
Hilling when the soil is waterlogged can promote waterlogging, rot, and disease
Incomplete plant establishment
Hilling too early can cause mechanical stress to young plants
Hilling too late
Leaving the bulb exposed to light for too long can cause it to turn green
Too much soil
Too much soil can hinder the plant’s proper development
Covered leaf stalks
The soil should cover the bulb without reaching the area where the leaf stalks emerge
Proper hilling should support the development of the bulb without hindering the plant’s growth.
Do you grow fennel and want to optimize its quality?
APOD supports its members with in-field technical advice, agricultural services, and product quality monitoring throughout the entire crop cycle.
Frequently asked questions about hilling fennel
