Fertilising guide

How to fertilise Kohlrabi 'Kolibri' (Brassica oleracea var. gongylodes 'Kolibri')— schedule & NPK

Also called Kolibri kohlrabi, purple kohlrabi.

More about kohlrabi 'kolibri'

About Kohlrabi 'Kolibri'

Brassica oleracea var. gongylodes 'Kolibri' · also called Kolibri kohlrabi, purple kohlrabi · edible

Kohlrabi 'Kolibri' is a fast purple-skinned F1 with crisp white flesh, swelling its edible stem into a tennis-ball globe in roughly 50-60 days. The vivid skin holds in heat, and the variety is slower to bolt than older types. Grow it in cool, fertile soil with steady moisture and harvest before bulbs turn woody.

Growth habit: Low rosette of blue-green leaves above a swollen, ground-level stem (the edible 'bulb') that sits on top of the soil rather than below it.

Watch for — Clubroot: Soil-borne disease swelling roots and stunting plants in acidic, wet ground. Rotate brassicas, improve drainage and lime to raise pH toward 7.0.

What fertiliser kohlrabi 'kolibri' actually wants — and why

Kohlrabi 'Kolibri' 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 kohlrabi 'kolibri': 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 kohlrabi 'kolibri', 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 kohlrabi 'kolibri':

Brassicas are heavy feeders. Work a balanced fertiliser into the bed at planting, then side-dress with nitrogen 3-4 weeks later. Avoid excess nitrogen late, which favours leaf over bulb. 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 kohlrabi 'kolibri' 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 kohlrabi 'kolibri'

Follow the crop-feed label rate for kohlrabi 'kolibri' — 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 kohlrabi 'kolibri' first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the kohlrabi 'kolibri' watering schedule.

Signs you are over-feeding kohlrabi 'kolibri'

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

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 kohlrabi 'kolibri'

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 kohlrabi 'kolibri' 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 kohlrabi 'kolibri' 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 kohlrabi 'kolibri'

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 kohlrabi 'kolibri' — frequently asked questions

What fertiliser does kohlrabi 'kolibri' 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. Kohlrabi 'Kolibri' 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 kohlrabi 'kolibri'?

Brassicas are heavy feeders. Work a balanced fertiliser into the bed at planting, then side-dress with nitrogen 3-4 weeks later. Avoid excess nitrogen late, which favours leaf over bulb. Brassicas are heavy feeders. Work a balanced fertiliser into the bed at planting, then side-dress with nitrogen 3-4 weeks later. Avoid excess nitrogen late, which favours leaf over bulb. 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 kohlrabi 'kolibri'?

What does over-feeding kohlrabi 'kolibri' 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 kohlrabi 'kolibri' 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 kohlrabi 'kolibri'?