Growing rosemary with Kratky hydroponics
Kratky Rosemary
Rosemary is the slowest herb on this site and the hardest to grow in a Kratky container. It can be done, mostly from cuttings and with patience.
The honest answer
Does Rosemary Grow with the Kratky Method?
It can, but set your expectations. Rosemary (Salvia rosmarinus) is a long-lived woody shrub from dry Mediterranean hillsides. It grows slowly, dislikes wet roots around its stem, and over a year or two becomes too big for a jar. Many growers use Kratky to root and grow young rosemary, then move it to a pot of soil.
Where it does work well is as a small kitchen plant you cut lightly and often. It needs the strongest light you have and a setup that keeps its stem base dry. Pruning rosemary for a dense shape is covered in how to cultivate your herbs.
slowestherb here
Getting started
Start Rosemary from a Cutting
Rosemary seed germinates poorly and slowly, so cuttings are the practical way to start.
Take a soft cutting
Cut a 4 to 6 inch tip of new, green (not woody) growth from a healthy plant.
Strip the lower needles
Remove the needles from the bottom 2 inches.
Root it
Stand it in water or a moist rockwool cube in bright, indirect light. Rosemary roots slowly: often three to six weeks or more. Change the water every few days.
Move it to a net pot
When the roots are an inch or two long, set it in a net pot of clay pebbles over the solution, with only the bottom of the pot touching.
Give it full light
As much direct sun as possible, or 14 to 16 hours under a grow light.
Care
Keeping Kratky Rosemary Healthy
- Keep the stem dry. Let the solution fall well below the net pot. A wet crown is the most common way rosemary fails.
- Go easy on nutrients. Rosemary needs less feeding than leafy herbs; some growers use it at half the label strength.
- Give it air. Good air movement around the plant helps prevent the powdery mildew rosemary gets indoors.
- Cut lightly. Snip green tips, never more than a fifth of the plant at once, and never into bare wood.
14-16hours of light
Moving on
When to Move Rosemary to Soil
When the roots fill the container and the plant has become woody and top-heavy, often within a year, it has outgrown Kratky. Rinse the roots, pot it in a fast-draining soil mix, and grow it on in a sunny window or outdoors. Keep a cutting going in water so you can start a new Kratky rosemary whenever you like.
Rosemary dries well, so even a small plant's harvest goes a long way; see preserving your herb harvest.
Problems
Common Kratky Rosemary Problems
Rosemary tells you when something is wrong, slowly. Watch for these signs.
- Needles browning from the base up: wet roots around the stem. Lower the level and keep the crown dry.
- Whole plant drooping: root rot from warm or stale solution. Take a cutting from healthy tips to start again.
- White powder on the needles: powdery mildew from still, humid air. Increase air movement and cut affected stems.
- Thin, pale new growth: not enough light, the most common indoor rosemary problem.
- No growth for weeks: normal for a newly moved cutting. Give it time before changing anything.
FAQ
Kratky Rosemary Questions
Why won't my rosemary cutting root?
It may be too woody, or it simply needs more time. Rosemary often takes over a month. Use soft, new growth and keep the water fresh.
Why is my rosemary turning brown at the base?
The stem is staying wet. Lower the solution level and use clay pebbles so the crown stays dry.
Can I grow rosemary from seed in Kratky?
It is possible but slow and unreliable. Cuttings are much easier.
How much light does rosemary need indoors?
More than most herbs: a south-facing window, or 14 to 16 hours under a grow light.
Can rosemary share a container with thyme and oregano?
They like similar dry, bright conditions, but rosemary is so slow that the others crowd it. Give it its own container.
Can I take rosemary cuttings from a store-bought sprig?
Sometimes, if the sprig is fresh with soft green tips. Woody, older sprigs rarely root.
How often should I harvest Kratky rosemary?
Lightly and often. Snip a few tips at a time once the plant is bushy, rather than taking a big harvest.
Is it worth growing rosemary with the Kratky method?
Yes, if you enjoy the process and use rosemary lightly. For a big, long-lived plant, root it in Kratky and then grow it on in soil.
Related Kratky Herbs
Thyme and oregano are rosemary's Mediterranean neighbors, and both grow faster.