Watering schedule

How often to water Kohlrabi (Brassica oleracea var. gongylodes) — the schedule

Also called German turnip, Turnip cabbage.

More about kohlrabi

Watering at a glance

Base rhythm	When the top 2-3 cm of soil is dry, about every 4-7 days
Spring / summer	Main season: aim for the equivalent of 2-3 cm of water per week as one or two deep soaks at the base, more in heat or during fruiting/sizing.
Autumn	Tail end of the season: ease back as temperatures drop and the plant winds down or ripens its last crop.
Winter	Off-season: most do not overwinter outdoors — store, mulch, or grow undercover; container plants need only occasional water if dormant.
Light	Direct sun (at least 4-6 hours)

About Kohlrabi

Brassica oleracea var. gongylodes · also called German turnip, Turnip cabbage · edible

Kohlrabi is a fast, easy brassica grown for its swollen, globe-shaped stem that sits above ground, with a crisp, mild, turnip-meets-cabbage flavour. Green and purple types crop in 8-10 weeks. Sow successionally from spring, keep it growing steadily in fertile, moist soil and full sun, and harvest while the bulbs are young and tender, before they turn woody.

Ideal humidity: Outdoor ambient

Watch for — Woody, split bulbs: Caused by drought, irregular watering or leaving bulbs too long. Keep moisture even and harvest young, ideally when the swollen stem is tennis-ball sized or smaller.

The watering schedule, season by season

Kohlrabi crops best on deep, regular soaks rather than light daily sprinkles — steady moisture at the roots is what fills and sizes the harvest. The base rhythm for kohlrabi is when the top 2-3 cm of soil is dry, about every 4-7 days, but the real interval moves with the season, the light and the pot — so treat the figures below as a starting point and always confirm with the plant itself.

Spring & summer (active growth): Main season: aim for the equivalent of 2-3 cm of water per week as one or two deep soaks at the base, more in heat or during fruiting/sizing.
Autumn (slowing down): Tail end of the season: ease back as temperatures drop and the plant winds down or ripens its last crop.
Winter (rest / dormancy): Off-season: most do not overwinter outdoors — store, mulch, or grow undercover; container plants need only occasional water if dormant.

Needs steady, even moisture (~25 mm/week) for crisp, tender bulbs. Irregular watering, especially drought followed by rain, causes the swollen stems to split and turn woody and stringy.

Want this turned into a live reminder that adjusts to your home and the weather? The Growli watering calculator takes your pot size, light and season and returns a starting interval for kohlrabi in seconds.

How to tell kohlrabi needs water

A calendar is the worst way to water kohlrabi. Check the plant and the soil instead — for this species, look for these signals in order:

Push a finger 3-4 cm into the soil — if it comes back dust-dry, water now.
Leaves wilt in the midday heat and do not fully recover by evening.
The soil surface is cracked or pulling away from the bed/pot edge.

The most reliable single check is the first one on that list. When two signals agree, water; when they disagree, wait a day and look again — under-watering kohlrabi for a day is almost always safer than over-watering it.

Overwatering vs underwatering kohlrabi

The two failure modes can look alike at a glance, so check the soil weight and wetness before you decide. For kohlrabi specifically:

Signs you are overwatering

Yellowing lower leaves and waterlogged, airless soil.
Root rot and wilting despite wet soil; fungal leaf spots from constantly wet foliage.
Split or cracked fruit/roots from a sudden glut after drought.

Signs you are underwatering

Persistent wilting, small or bitter produce, premature bolting.
Blossom-end rot on tomatoes/peppers/squash from erratic moisture.
Tough, woody or cracked roots in root crops.

Shallow, frequent watering grows shallow roots and leaves kohlrabi prone to drought stress — cracked or woody roots, bitterness and premature bolting. Water deep and at the base, not little-and-often over the leaves.

Water quality notes

Tap water is fine for kohlrabi; consistency and depth matter far more than water type. Water early in the day at soil level to limit fungal disease.

Seasonal and environmental adjusters

Every figure above shifts with the conditions in your home. For kohlrabi, the levers that matter most are:

Mulch heavily — it evens out soil moisture and roughly halves how often you need to water.
In full sun and heat the soil dries fast; a heatwave can double the watering frequency.
Containers dry far faster than open ground and may need water daily in summer.

Pot choice is part of this too — work out the right size with the pot size calculator, since a pot that is too big stays wet long enough to rot the roots of kohlrabi.

Kohlrabi watering — frequently asked questions

How often should I water kohlrabi?

Water kohlrabi when the top 2-3 cm of soil is dry, about every 4-7 days. Main season: aim for the equivalent of 2-3 cm of water per week as one or two deep soaks at the base, more in heat or during fruiting/sizing. Off-season: most do not overwinter outdoors — store, mulch, or grow undercover; container plants need only occasional water if dormant.

How do I know when kohlrabi needs water?

Push a finger 3-4 cm into the soil — if it comes back dust-dry, water now. Leaves wilt in the midday heat and do not fully recover by evening. The soil surface is cracked or pulling away from the bed/pot edge. The single most reliable test for kohlrabi is the first signal on that list — checking the soil or the plant directly always beats watering by the calendar.

What does an overwatered kohlrabi look like?

Yellowing lower leaves and waterlogged, airless soil. Root rot and wilting despite wet soil; fungal leaf spots from constantly wet foliage. Split or cracked fruit/roots from a sudden glut after drought. Shallow, frequent watering grows shallow roots and leaves kohlrabi prone to drought stress — cracked or woody roots, bitterness and premature bolting. Water deep and at the base, not little-and-often over the leaves.

What are the signs of an underwatered kohlrabi?

Persistent wilting, small or bitter produce, premature bolting. Blossom-end rot on tomatoes/peppers/squash from erratic moisture. Tough, woody or cracked roots in root crops.

Can I use tap water on kohlrabi?