Kratky Herb Kit: Growing Herbs on a Windowsill

A Kratky herb kit on a windowsill is one of the most practical ways to use passive hydroponics: fresh basil, mint or parsley within reach of the stove, with no soil to spill and no daily watering. Herbs are small, fast and forgiving, which makes them ideal for a first kit.

Herbs that do well in a Kratky kit

• Basil: loves warmth and bright light; one of the most productive herbs in hydroponics.
• Mint: grows vigorously; give it its own container so it does not crowd other herbs.
• Parsley: slow to sprout but steady once it is growing.
• Chives: compact and easy to keep cutting.
• Cilantro: prefers cooler conditions and can bolt quickly in heat.
• Oregano, thyme and dill: worth trying in small containers.

The best plants for Kratky guide compares herbs with greens and fruiting plants.

One container or several?

Herbs differ in how fast they grow and drink. Growing each herb in its own jar, or grouping herbs with similar needs, makes it easier to manage the water level and harvest. A countertop kit with several sites works well for a mix of herbs if each site has enough solution. See Kratky containers for sizes.

Setting up a windowsill herb kit

1. Choose the brightest window you have. In the Northern Hemisphere, a south-facing window usually gets the most light.
2. Block light from the solution: use an opaque container or cover a clear one.
3. Mix a complete hydroponic nutrient at the label rate for leafy plants and adjust pH; see Kratky nutrients and Kratky pH.
4. Fill until the solution touches the bottom of the net pot and plant the seedling.

Full steps are in Kratky kit setup. To build a single herb jar from scratch, see the DIY Kratky kit from a mason jar.

Is a windowsill bright enough?

In summer, a bright, unshaded window can be plenty for many herbs. In winter, light drops sharply, and herbs may become leggy and pale. If that happens, a small LED grow light over the windowsill makes a big difference. See Kratky grow lights. Also watch for heat: direct sun through glass can warm a container, and warm solution holds less oxygen.

Harvesting to keep herbs growing

• Basil: cut stems just above a pair of leaves. Two new shoots grow from that point, making the plant bushier. Pinch off flower buds to keep leaves coming.
• Mint: cut stems back regularly; it regrows quickly.
• Parsley and cilantro: take outer stems from the base and leave the center to grow.
• Chives: cut a few leaves near the base.

Harvesting little and often keeps herbs compact, which also slows how fast they drink.

The Kratky harvest guide shows where to cut each kind of herb.

Keeping herbs going for months

Unlike a lettuce that is harvested and done, herbs can be kept growing for a long time. That means the solution may run low. When it does, add solution to a lower level only, keeping the upper roots in the air gap. The article on how often to refill a Kratky kit explains how.

Starting herbs from cuttings

Basil and mint root easily from cuttings. Take a healthy stem, remove the lower leaves, and stand it in water until roots form, then move it into a net pot with clay pebbles. This skips the seed stage entirely. For seeds, see starting seeds for a Kratky kit.

Common herb problems

• Leggy, floppy stems: too little light.
• Cilantro or basil flowering early: heat or stress; harvest and pinch buds.
• Green film in a jar: light reaching the solution.

More fixes are in Kratky problems and fixes.

Go deeper: guides to individual herbs are at Kratky Herbs, our sister site on growing herbs with the Kratky method.

Frequently asked questions