The secret to growing leeks in New Zealand
As summer stumbles along we’re heading into winter crop planting time and leeks are one crop that are best planted sooner rather than later.
Words: Jane Wrigglesworth
Many gardeners plant their leeks in autumn, hoping they’ll fatten up in time for winter picking. The trick to fat winter leeks is to plant them early to ensure they have enough time to grow before winter picking. Leeks can take up to six months to mature after transplanting.
Although some of the newer cultivars have been bred for quicker maturity – three to four months – maturity times are often affected by temperature, available nutrients and water. That’s another reason why a lengthy season is needed.
• Leeks like a soil that is rich in organic matter. Dig in plenty of compost or well-aged manure a couple of weeks before planting.
• Add fertiliser too. As a leafy crop, leeks benefit from a fertiliser that’s high in nitrogen, which promotes leaf growth.
• Other good options are aged manure, especially well-rotted chook manure, and worm castings, another excellent source of nutrients.
• Position seedlings in full sun in moist but well-drained soil. If your soil is shallow or drainage is poor, plant in raised beds.
• Use a dibber 5cm in diameter to poke holes in the soil, 15cm deep and 15cm apart. Gently ease your seedlings out of their pots and place one in each hole. Don’t backfill the hole with soil. Just water each one so that enough soil falls into it to cover the roots of the seedlings. As the leeks grow, the holes will gradually fill with soil.
• Water young plants well until they become established. Feed regularly with an organic fertiliser tea or generic liquid fertiliser.
HOW TO BLANCH THE STEMS FOR MORE EDIBILITY
The white and palest green parts of the leek are most commonly used in cooking, so growers typically blanch the stems to increase the proportion of stem that’s edible and to sweeten the taste. This process is usually started around mid-autumn, or when your leeks are nearly fully grown.
• Tie a paper collar around each stem and gently hill the earth up around the stem. Be careful not to get soil between the paper collar and stem as the leek may rot.
• As the plants continue to grow, you can fit another collar above the first one and hill up more soil.
• Slugs and snails may take up residence within the paper collars, so keep an eye out for them.
THE WINTER HARVEST
• Leeks can be harvested when stems are around 2.5cm in diameter (although gourmet baby leeks can be harvested much earlier).
• They can be left in the ground until needed too. However, don’t leave them too long or they’ll start to develop a seed head, which diminishes quality.
• Gently dig each leek out with a garden fork. If you pull the top there’s a good chance it will break.