The Purple Kohlrabi: A Garden Gem Often described as looking like a "space vegetable" or a Sputnik satellite, the Purple Kohlrabi (Brassica oleracea) is a vibrant, alien-looking member of the cabbage family. Despite its name "German Turnip," it isn't a root vegetable; the edible bulb is actually a swollen stem that grows just above the soil.

Appearance and Texture The Exterior: Features a stunning, deep violet or royal purple skin. The colour is purely superficial—once you peel it, the flesh inside is a crisp, creamy white.

The Leaves: Long, sturdy green stems (petioles) sprout from the bulb, topped with waxy, kale-like leaves.

The Crunch: It has a dense, snappy texture similar to a broccoli stem or a very crisp apple.

Flavour Profile The taste of Purple Kohlrabi is often described as a milder, sweeter version of broccoli stems or cabbage heart. It carries a subtle peppery undertone (reminiscent of a radish) but finishes with a distinct nutty sweetness.

Pro Tip: Purple kohlrabi tends to be slightly sweeter and more pest-resistant than the green variety, though they can be used interchangeably in recipes.

Selection and Storage When shopping or harvesting, look for bulbs about the size of a tennis ball. Larger bulbs can become "woody" and fibrous, losing that signature crispness.

Storage: Remove the leaves (store them separately) and keep the bulb in the crisper drawer. It will stay crunchy for several weeks.

Prep: The skin on purple kohlrabi can be a bit tough, so it’s best to use a vegetable peeler or a knife to remove the purple outer layer until the pale white flesh is revealed.

How To Grow

Growing purple kohlrabi is incredibly rewarding because it’s one of the fastest-maturing vegetables in the garden. It thrives in the cool shoulders of the season—spring and autumn—and that purple skin looks absolutely stunning against green garden foliage.

1. Timing and Temperature Kohlrabi is a cool-season crop. It can tolerate a light frost, which actually makes the bulb taste sweeter. Spring Crop: Sow seeds 4–6 weeks before the last frost. Autumn Crop: Sow seeds in late summer (about 6–8 weeks before the first hard frost) for a late-season harvest. Ideal Temp: It grows best when temperatures are between 7°C and 24°C.

2. Soil and Site Prep Sunlight: Full sun is best (at least 6 hours a day).Soil: It needs rich, well-draining soil with plenty of organic matter. pH Level: Aim for a slightly acidic to neutral soil, roughly 6.0/6.8.

3. Sowing and Spacing You can start seeds indoors, but kohlrabi has a sensitive taproot, so direct sowing is usually more successful. Depth: Plant seeds 1cm deep. Spacing: Space seeds about 5cm apart, then thin them to 10–15cm apart once seedlings are a few inches tall. Row Spacing: Keep rows about 30cm apart to allow for airflow.

4. Care and Maintenance The secret to a tender kohlrabi (rather than a woody one) is rapid, uninterrupted growth. Watering: Keep the soil consistently moist. If the soil dries out and then gets drenched, the bulbs can split. Mulching: Use straw or compost around the base to retain moisture and keep the roots cool. Feeding: If your soil is already rich, you won't need much. Otherwise, a balanced organic fertilizer applied once mid-season is plenty.

How/When To Harvesting

Harvesting Purple Kohlrabi is all about timing. Because it is a stem rather than a root, you can actually watch your progress daily as the purple "bulb" expands above the soil line.

Here is the step-by-step guide to getting the best flavour and texture from your harvest.

1. The "Golden Rule" of Size The most common mistake is waiting too long. Kohlrabi is at its peak sweetness and "apple-like" crunch when it is between 5cm and 8cm (2–3 inches) in diameter.

Small (Golf ball size): Extremely tender, skin is often thin enough to eat without peeling.

Medium (Tennis ball size): The "sweet spot" for most culinary uses.

Large (Grapefruit size): Avoid waiting this long. The interior becomes "woody" and fibrous, making it tough to chew.

2. The Harvest Process You don’t need to pull the whole plant out like a carrot. Instead, follow these steps:

Identify the Base: Locate the thin part of the stem between the purple bulb and the soil.

The Cut: Use a sharp garden knife or heavy-duty shears. Slice through the main stem about 1cm (half an inch) below the bulb.

Leaf Management: Once the bulb is free, trim away the long leaf petioles (stems) sprouting from the sides of the bulb.

Note: Do not discard the leaves! They are delicious and can be cooked like kale

A Quick Note on Peeling While the purple skin is beautiful, it can be quite fibrous on larger bulbs.

For Raw Eating: Use a vegetable peeler or paring knife to remove the purple skin until you reach the pale, creamy white flesh.

For Very Small Bulbs: If harvested very young (5cm or less), the purple skin is often tender enough to leave on for a pop of colour in your dish.