Purple Kohlrabi microgreens are colourful, fast-growing brassica seedlings with vivid purple to mauve stems, dark green cotyledons and a mild, fresh cabbage-like flavour. They are relatively easy to grow and are well suited to beginners looking for a colourful alternative to broccoli, kale or cabbage microgreens.
If you are learning how to grow Purple Kohlrabi microgreens, the process is straightforward. The seeds do not normally require soaking, germinate quickly and can be grown in shallow trays using soil, coco coir, hemp growing mats or another suitable microgreen growing medium.
This step-by-step guide explains how to sow, germinate, cover, water, light and harvest Purple Kohlrabi microgreens, as well as how to avoid common problems such as mould, uneven germination and weak growth.
Purple Kohlrabi Microgreens at a Glance
What Are Purple Kohlrabi Microgreens?
Purple Kohlrabi microgreens are the young seedlings of Brassica oleracea var. gongylodes, the same plant that develops into mature kohlrabi when allowed to grow for several weeks.
Kohlrabi belongs to the Brassicaceae family, along with broccoli, cabbage, kale, cauliflower and mustard.
At the microgreen stage, the plant has not yet developed the enlarged swollen stem associated with mature kohlrabi. Instead, growers harvest the tender stems and seed leaves while the seedlings are still young.
Purple varieties are particularly attractive because they develop purple, pinkish or mauve stems beneath dark green cotyledons.
What Do Purple Kohlrabi Microgreens Taste Like?
Purple Kohlrabi microgreens have a mild, fresh brassica flavour with a slightly sweet cabbage-like character.
The flavour is generally much milder than mustard or radish microgreens and is similar to young cabbage, broccoli stems or mature kohlrabi.
Because the flavour is relatively gentle, Purple Kohlrabi works well both on its own and as part of a mixed microgreen crop.
They can be used in:
- Salads
- Sandwiches
- Wraps
- Grain bowls
- Cold noodle dishes
- Platters
- Restaurant-style garnishes
- Mixed microgreen trays
Why Grow Purple Kohlrabi Microgreens?
- Fast-growing microgreen crop.
- Distinctive purple to mauve stems.
- Mild flavour that works well in mixed microgreen crops.
- No seed pre-soaking required.
- Suitable for growing indoors throughout the year.
- Can be grown in soil, coco coir or suitable microgreen growing mats.
- Relatively easy for beginners.
- Useful for adding colour without introducing a strongly spicy flavour.
- Suitable for home and commercial microgreen production.
Are Purple Kohlrabi Microgreens Easy to Grow?
Yes. Purple Kohlrabi is generally an easy microgreen crop.
The seed is small but germinates readily without soaking. The crop establishes quickly and follows essentially the same growing method used for broccoli, Red Cabbage, kale and other small-seeded brassicas.
One practical difference is that kohlrabi seed is quite round. On an uneven growing surface, the seeds can roll into low areas and form dense clumps.
Taking a little extra time to level the growing medium and distribute the seed evenly can therefore improve crop uniformity.
How to Grow Purple Kohlrabi Microgreens in 7 Simple Steps
- Prepare the growing tray. Add approximately 3–4 cm of moist growing medium and level the surface carefully.
- Sow the Purple Kohlrabi seeds. Spread approximately 10–20 g evenly across a standard 10 × 20 inch tray.
- Mist thoroughly. Moisten the seed and growing surface without washing the seed into clumps.
- Cover the tray. Place another tray or suitable cover over the seeds during initial germination.
- Move the seedlings into light. Remove the cover once germination is established and the seedlings are pushing upward.
- Water carefully. Bottom water once roots are established and keep the medium evenly moist rather than saturated.
- Harvest. Cut the crop just above the growing medium at approximately 10–15 days, depending on growing conditions and your preferred harvest stage.
What You Need to Grow Purple Kohlrabi Microgreens
- Purple Kohlrabi microgreen seeds
- Shallow growing tray with drainage holes
- Solid bottom watering tray
- Second tray or suitable germination cover
- Soil, seed-raising mix, coco coir or suitable microgreen mat
- Spray mister
- Clean water
- Suitable natural light or LED grow light
- Clean scissors or harvesting knife
Do Purple Kohlrabi Microgreen Seeds Need to Be Soaked?
No. Purple Kohlrabi seeds do not normally require soaking before sowing.
The seeds absorb moisture readily from a damp growing medium and usually begin germinating within a few days under suitable conditions.
Pre-soaking small brassica seeds can also make them more difficult to distribute evenly.
Sow the seeds dry and mist them thoroughly after planting.
How Much Purple Kohlrabi Seed Should You Use?
A practical starting range is approximately 10–20 grams per standard 10 × 20 inch microgreen tray.
For a 10 × 10 inch tray, approximately 5–10 grams provides a corresponding starting range.
Commercial recommendations vary because tray dimensions, seed lots, harvest stage and production systems differ.
The aim is not to pack the maximum possible number of seeds onto the tray. Instead, sow densely enough to create a full canopy while still allowing reasonable airflow between seedlings.
If your crop consistently develops mould or weak stems, reducing the sowing rate slightly may help.
Best Growing Medium for Purple Kohlrabi Microgreens
Purple Kohlrabi grows successfully in several different media.
Seed-Raising Mix or Fine Potting Mix
A fine-textured seed-raising or quality potting mix is generally the easiest medium for beginners.
Add approximately 3–4 cm to the tray and gently level the surface.
The medium should be evenly moist before sowing without being waterlogged.
Coco Coir
Coco coir provides a clean, uniform growing surface with good moisture retention.
Moisten the coir before filling the tray and allow excess water to drain.
Level the surface particularly carefully because round kohlrabi seeds can otherwise roll into hollows.
Hemp Growing Mats
Purple Kohlrabi can also be grown on suitable hemp microgreen growing mats.
Thoroughly wet the mat before sowing and allow excess water to drain.
During growth, maintain consistent moisture without leaving the mat submerged in water for prolonged periods.
Best Temperature for Purple Kohlrabi Microgreens
A practical indoor growing range is approximately 18–24°C.
Kohlrabi is a cool-season brassica, so it generally performs well at moderate temperatures.
When temperatures rise, especially in humid conditions, disease pressure can increase.
For growers in warm Australian climates, airflow and careful watering become increasingly important during summer.
Step 1: Prepare the Growing Tray
Start with clean trays and equipment.
Add approximately 3–4 cm of your chosen growing medium to a shallow tray.
Gently level the surface without heavily compacting it.
This step is especially important with Purple Kohlrabi because its small, round seeds can easily roll into dips in the growing medium.
Moisten the medium evenly before sowing. It should be damp throughout but should not contain pools of standing water.
Step 2: Sow the Purple Kohlrabi Seeds
Spread the seed evenly across the growing surface.
For a standard 10 × 20 inch tray, start with approximately 10–20 grams.
Keep your hand or seed shaker relatively close to the tray while sowing so the round seeds do not bounce away from the growing surface.
Once the seed is distributed, gently move any obvious clumps into sparse areas.
Lightly press the seed against the medium to improve seed-to-medium contact.
Finish by misting thoroughly with clean water.
Step 3: Cover the Tray During Germination
Place another tray or suitable germination cover over the seeded tray.
The cover helps maintain humidity and darkness while the seeds germinate.
Purple Kohlrabi commonly begins germinating within approximately 2–4 days.
Check the crop regularly and maintain even moisture without saturating the growing medium.
Do Purple Kohlrabi Microgreens Need Weight?
Purple Kohlrabi does not normally require heavy weighting.
A second tray can provide light, even pressure during early germination and improve seed-to-medium contact.
Heavy weights such as those often used for pea or sunflower microgreens are unnecessary.
How Long Should Purple Kohlrabi Stay Covered?
Approximately 2–3 days provides a useful starting point for covered germination.
However, the condition of the seedlings is more important than following an exact timetable.
Once germination is well established and the seedlings are pushing upward against the cover, remove the tray and introduce the crop to light.
Avoid unnecessarily extending the blackout period because this can produce overly elongated stems.
Step 4: Introduce the Seedlings to Light
After germination, remove the cover and place the crop under suitable natural or artificial growing light.
The seedlings may initially appear pale after being covered. This is normal.
As the cotyledons receive light, they begin turning green while the stems develop their characteristic purple to mauve colouring.
Adequate light also helps produce shorter, stronger and more compact seedlings.
How Much Light Do Purple Kohlrabi Microgreens Need?
Purple Kohlrabi requires good light after germination.
A bright windowsill can be suitable for small crops when enough light is available, but an LED grow light generally provides more consistent indoor production.
Avoid very hot windowsills or intense afternoon sun behind glass, as tray temperatures can rise quickly.
If using grow lights, position them according to the manufacturer’s recommendations so the crop receives useful light without excessive heat.
Why Do Purple Kohlrabi Microgreens Develop Purple Stems?
The purple colouring is produced by naturally occurring plant pigments called anthocyanins.
The intensity of the colour can vary with cultivar, light, temperature, crop age and growing conditions.
Scientific research has also investigated Purple Kohlrabi microgreens under different light spectra and growing systems, confirming that light environment can influence plant growth, pigmentation and other characteristics.
You can read more in this peer-reviewed study of Brassicaceae microgreens including kohlrabi grown under different LED light spectra.
Step 5: Water Purple Kohlrabi Microgreens Carefully
During early germination, mist the tray as needed to maintain surface moisture.
Once roots have established through the growing medium, bottom watering is generally preferable.
Add water to the solid lower tray and allow the medium to absorb moisture through the drainage holes.
This helps keep the foliage drier and reduces unnecessary moisture across a dense microgreen canopy.
Avoid:
- Waterlogged growing media
- Standing water beneath the tray for long periods
- Constantly wet foliage
- Allowing the growing medium to dry completely
- Heavy overhead watering that knocks seedlings over
Step 6: Allow the Cotyledons to Develop
Once exposed to light, Purple Kohlrabi seedlings develop rapidly.
The rounded cotyledons expand and the canopy becomes increasingly dense.
Healthy seedlings should develop slender purple to mauve stems topped with dark green seed leaves.
Maintain consistent moisture, suitable light and good airflow during this stage.
Step 7: When to Harvest Purple Kohlrabi Microgreens
Purple Kohlrabi microgreens are commonly harvested approximately 10–15 days after sowing.
Some production systems harvest slightly earlier, so use crop development rather than the calendar alone to decide when to cut.
Look for:
- Fully opened cotyledons
- Strong purple or mauve stem colour
- Dark green foliage
- Healthy upright growth
- Approximately 5–8 cm of height
- Tender stems
- Little or early true-leaf development
You can harvest earlier for a smaller, more delicate crop or allow the seedlings to develop slightly longer if you prefer a larger microgreen.
How to Harvest Purple Kohlrabi Microgreens
Use clean scissors or a sharp harvesting knife.
Cut the stems just above the growing medium, taking care not to include soil, coir or pieces of growing mat.
Where practical, harvest while the crop is reasonably dry rather than immediately after watering.
Purple Kohlrabi should normally be treated as a single-cut crop. Sow a fresh tray for your next harvest.
How to Store Purple Kohlrabi Microgreens
Harvested microgreens generally store best when excess surface moisture is kept to a minimum.
If the crop is wet at harvest, allow it to drain before refrigeration.
Store the microgreens in a clean container in the refrigerator.
A small amount of absorbent paper can help manage condensation.
As with all fresh produce, discard microgreens that develop obvious spoilage, unpleasant odour or visible mould.
Purple Kohlrabi vs Broccoli Microgreens
Purple Kohlrabi and broccoli are closely related brassica microgreens and are grown using similar methods, but their appearance and flavour differ.
Purple Kohlrabi vs Red Mustard Microgreens
Purple Kohlrabi and Red Mustard can both introduce attractive colour into a microgreen mix, but their flavour profiles are very different.
Purple Kohlrabi Microgreens vs Mature Kohlrabi
Purple Kohlrabi microgreens and mature kohlrabi come from the same plant but are harvested at completely different stages.
Growing Purple Kohlrabi Microgreens in Warm and Humid Weather
Purple Kohlrabi is a brassica, and dense brassica microgreen crops can become more difficult to manage in warm, humid conditions.
For growers in subtropical areas such as Brisbane, the combination of warmth, moisture and limited airflow can increase the risk of mould and damping-off.
During warm or humid weather:
- Provide good airflow around trays
- Avoid unnecessarily heavy sowing rates
- Bottom water after the roots establish
- Avoid persistently saturated growing media
- Do not leave trays sitting in excess water
- Move established seedlings into light promptly
- Avoid very hot windowsills
- Consider gentle air movement where indoor conditions are stagnant
Moisture is essential for a healthy crop, but more water is not necessarily better. The growing medium should remain evenly moist while still allowing oxygen around the root zone.
Common Problems When Growing Purple Kohlrabi Microgreens
Mould
Mould is more likely when seed is sown too densely, airflow is limited or the growing medium remains excessively wet.
Reduce risk by using clean trays, sowing evenly, providing good ventilation and avoiding waterlogged media.
Discard visibly mouldy or spoiled microgreens rather than eating them.
White Fuzz Around the Roots
Fine white hairs immediately surrounding healthy roots are often root hairs rather than mould.
Root hairs usually form uniformly around individual roots and can become less visible after misting.
Mould is generally more irregular and can spread across seed hulls, stems or the surface of the growing medium.
Uneven Germination
Uneven germination can result from inconsistent moisture, poor seed-to-medium contact or uneven seed distribution.
Because Purple Kohlrabi seed is round, it can roll into depressions in the tray. Make sure the growing surface is level before sowing.
Pale Seedlings After Germination
Seedlings may be pale or yellow immediately after covered germination.
This is normal. Introduce the crop to suitable light and the leaves should begin turning green while the stems develop stronger purple colouring.
Weak or Leggy Growth
Excessively tall, thin seedlings may indicate inadequate light or too much time under the germination cover.
Move established seedlings into light promptly and make sure the light level is sufficient.
Poor Purple Colour
Colour intensity varies with genetics and growing conditions.
Insufficient light can produce paler seedlings, while temperature and crop age can also affect the final shade.
Seedlings Falling Over
Check for overcrowding, inadequate light, overwatering, damping-off or poor airflow.
Reducing sowing density slightly can help if trays consistently develop weak, crowded growth.
Wilting
If otherwise healthy seedlings wilt, check whether the growing medium has become dry.
As the canopy develops, the tray can use water increasingly quickly.
If the medium is already very wet, avoid automatically adding more water and instead inspect drainage and the base of the stems for signs of disease.
Frequently Asked Questions
How long do Purple Kohlrabi microgreens take to grow?
Purple Kohlrabi microgreens are commonly ready for harvest approximately 10–15 days after sowing. Some growers harvest slightly earlier depending on their growing system and preferred crop stage.
Do Purple Kohlrabi microgreen seeds need soaking?
No. Purple Kohlrabi seeds do not normally require pre-soaking.
How much Purple Kohlrabi seed should I use in a 10 × 20 tray?
Approximately 10–20 grams provides a useful starting range for a standard 10 × 20 inch tray.
How much seed should I use in a 10 × 10 tray?
Approximately 5–10 grams provides a useful starting range for a 10 × 10 inch tray.
How long do Purple Kohlrabi seeds take to germinate?
Germination commonly begins within approximately 2–4 days under suitable conditions.
Do Purple Kohlrabi microgreens need blackout?
A short period of covered or dark germination is useful. Approximately 2–3 days provides a practical starting point, although seedling development should determine when you remove the cover.
Do Purple Kohlrabi microgreens need weight?
Heavy weighting is not normally necessary. A second tray can provide light, even pressure during germination.
When should Purple Kohlrabi microgreens be uncovered?
Remove the cover once most of the seeds have germinated and the seedlings are established and pushing upward.
Can Purple Kohlrabi microgreens be grown without soil?
Yes. They can be grown using suitable soilless media including coco coir and purpose-made microgreen growing mats.
Can Purple Kohlrabi microgreens be grown indoors?
Yes. Purple Kohlrabi is well suited to indoor microgreen production when sufficient light, moisture and airflow are provided.
Can Purple Kohlrabi microgreens grow on a windowsill?
Yes, provided the windowsill receives adequate light and does not become excessively hot. Grow lights provide more consistent conditions where natural indoor light is limited.
Why are Purple Kohlrabi microgreens purple?
Purple varieties contain naturally occurring anthocyanin pigments. Colour intensity can vary according to genetics, light, temperature and crop age.
What do Purple Kohlrabi microgreens taste like?
They have a mild, fresh cabbage and kohlrabi flavour with considerably less pungency than mustard or radish microgreens.
Are Purple Kohlrabi microgreens spicy?
They are generally mild rather than strongly spicy. They have a fresh brassica character with a gentle cabbage-like flavour.
When should I harvest Purple Kohlrabi microgreens?
Harvest once the cotyledons are fully developed, the stems have good colour and the plants are still tender. This commonly occurs approximately 10–15 days after sowing.
Do Purple Kohlrabi microgreens regrow after cutting?
Purple Kohlrabi is generally treated as a single-cut crop. Sow a new tray for each harvest.
Can Purple Kohlrabi be mixed with other microgreens?
Yes. Its colourful stems and mild flavour make it particularly useful in blends with broccoli, kale, cabbage, mustard and radish microgreens.
Final Tips for Growing Purple Kohlrabi Microgreens
Purple Kohlrabi is an attractive and relatively forgiving microgreen for beginners. Its purple to mauve stems provide excellent colour contrast while its mild flavour makes it easy to use with other microgreen varieties.
For reliable results, sow approximately 10–20 g per 10 × 20 inch tray, keep the growing surface level, maintain even moisture during germination, uncover the seedlings once they are established and provide adequate light and airflow.
Avoid overwatering and excessive sowing density, particularly during warm or humid weather.
Under suitable conditions, Purple Kohlrabi microgreens can commonly be harvested approximately 10–15 days after sowing.
Ready to grow your own? Shop Purple Kohlrabi Microgreen Seeds from Seedmart Australia.