Leek growing - Leeks how to grow, tips, varieties, cooking.
If you ask any gardener with a vegetable plot have they grown onions, nine times out of ten they will reply with a “yes”. Now that onion may have been a bulbing onion, a spring onion (scallion), or even at a stretch they will have grown garlic and made that link to the onion. However ask that same group of gardeners have they grown leeks, and you will be lucky to get one yes reply in ten.
From one angle this amazes me as leeks only a touch more troublesome than onions to grow. OK, they occupy your land for longer period of time, but they are way more forgiving of poor fertility than any onions grown from seed. They are also pretty “bomb-proof” to most of the common garden pests such as slugs, greenfly and caterpillars, so what’s holding us back from growing them.
I pressed gardeners for more reasons why they don’t grow this versatile vegetable. Finally a few offered up the reason that they can’t be bothered with the transplanting and earthing up of leeks, or are unsure of how to go about this task.
I hope that this post will demystify the leek growing process….
Poor man’s asparagus, flags, poireau, or ramps.
Area of origin:
Mediterranean and Egypt.
Although a member of the onion family our leek never forms much of a bulb at its base, a slightly enlarged stalk is as big as it gets. Also whereas onion plants comprise vertical hollow shoots, leek leaves are flat and straplike. However one of the main factors it does have in common with the onion is that If left to flower (inadvisable for kitchen use), the leek plant will produce a ball-like cluster of white or lavender flowers.
Are they easy or hard to grow?:
Reasonably easy to grow once soil is suitable. However they will occupy your land for a long time.
Varieties suitable to grow in Ireland:
Musselburgh (Thick stemmed and broad leafing, a hardy Scottish variety with tender white bases, fine mild flavour)
Argenta (Crisp white bases with a mild flavour, bolt and frost resistant)
King Richard (long narrow stems, ideal as mini leeks when transplanting is omitted.
Lyon 2 Prizetaker (thick white stems with a sweet mild flavour, frost resistant heirloom variety)
When to grow:
Leeks for common kitchen use are usually sown from the middle of March onwards, when soil begins to become warm to the touch. If soils are still wet and cold, hold off for a while, as sowing in such situations can result in poor germination and fungal attack. A March sowing can begin harvesting from November onwards. Sowing successionally at fortnightly intervals up until June will extend your harvest if you like your leeks especially tender. Otherwise bulk batch sown leeks can be left in the soil and pulled as required.
Where to grow, and soil conditions required:
Leeks grow best in an airy sunny location on fertile soil that drains well. Avoid at all costs soil that waterlogs or conversely dries out rapidly. Leeks are slightly more forgiving of poor fertility than onions grown from seed.
Leeks don’t grow very well in a strongly acid soil preferring instead neutral to slightly alkaline soils (6.0 - 8.0 approx). If the pH (relative acidity or alkalinity) of your soil is not suited to the vegetable, then soil nutrients such as Nitrogen, Phosphorus, Potassium, iron, boron, copper, manganese and zinc start to become unavailable, leading to poor crops.
You can use a home soil test available in most garden centres to determine your soils ph. By taking account of the test results you can then decide how much if any amendments are required to bring the to pH of your vegetable garden soil in line.
The application of ground lime will be helpful in countering the acidity. As a rough rule of thumb an application of 250g of ground lime per metre squared the autumn before planting/sowing will commonly increase your ph by about one point. However as lime is available in different formulations, I advise also consulting the rates set out on the pack.
Food reserves required:
For long term feeding of your crop, every 10m2 of growing area should have one wheelbarrow load of well-rotted homemade compost or farmyard animal manure spread over its surface sometime during the autumn/early winter before planting/sowing. Dig this in to a spades depth all over the proposed growing area to enrich it for your crop. Whilst digging, remove any stones and other obstacles that might obstruct roots.
As a rule of thumb, well-rotted manure/compost will be over six months old, and tend to be dark brown will little if any smell. You should not be able to distinguish individual pieces of straw, hay, vegetable peelings, grass etc., as it will all be rotted down.
A week or two before planting/sowing you should also lightly rake into your growing area a well-balanced fertilizer. Growmore or fish blood and bone (organic option) are both suitable for this purpose. Apply according to the rates on the pack.
How to plant or sow:
In your weed-free and lightly raked growing area you must create a shallow drill 1/2 inch (1cm) deep. Sprinkle the seeds very thinly along this drill aiming for a seed every 1 ½ in (4cm) along the row.
However, because the seeds are so small many gardeners opt to firstly mix the seeds with a quantity of dry sharp sand. Then they will lightly dust the mix out along the drill by working their thumb across their fingers. Whatever way the seeds are sown, don’t forget to close the drill with soil, then water well and label.
The distance between the drills should be 12 to 18 inches. The wider spacing is preferable as it allows room to get between the rows to weed and maintain your crop. The expected seed germination time is approx 14-18 days. Any seed not required for sowing that year should be kept dry as it has a life expectancy of 3 years.
Why should you transplant? Transplanting increases the length of white stem on your leeks, so you end up with more usable vegetable from each individual leek. The stem whitens through deeper planting leading to light deprivation, a change from green to white, which is the resultant blanching.
If transplanting, the young plants should be ready for moving when they are about 8in (20cm) high and as about as thick as a pencil. Water the ground deeply around the young plants the day before you intend to move them, as this will prevent damage and shock to them.
The transplants new growing bed should have been prepared sometime during the autumn/early winter before sowing, in a similar way as described earlier in this guide. To transplant you can use a dibber. This is usually a plastic, metal or wooden hand tool, 6-inches long with a pointed tip; primarily used to make holes in soil for planting and transplanting seedlings, bulbs etc. You can buy one of these or take the frugal option and whittle one out of a broken broom handle or better still an old garden fork or spade shaft (complete with T or D handle).
With your dibber make rows of 6-inch (15cm) deep holes in the transplanting area at 6-9 inches apart. Allow 12 inches (30cm) between each of the plant rows. Then from your seedbed, lift out the young leek plants with a trowel or hand-fork. Lightly trim off the root tips and leaf tips before dropping the transplant into the holes leaving just the tips of the leaves showing. The plants can be kept damp throughout the time it takes to plant them by lightly wrapping bunches of them in damp sacking or wet newspaper.
Finally you must gently fill the hole with water to settle the roots. Use a watering can with its rose removed for this task. To prevent soil to falling between the leaves do not fill the transplant hole with soil, instead over time the holes will fill up of their own accord.
When the transplants have settled in well, and are showing good upward growth, then you can look earth up the stems to blanch them further. Earthing up is as simple as gently drawing soil up around the stems with a garden hoe or spade whilst being careful not to allow any fall between the leaves. You can carry out the earthing up over a few stages to vastly increase your percentage of white stem.
A lot of gardeners ask me “do you really have to transplant and earth up leeks”? No you don’t have to. You will still have perfectly usable leeks albeit with less crisp white stem. The choice is up to you.
Caring for your crop:
Keep the soil around the leek plants weed-free. Take care when weeding because the roots and stems are easily damaged.
During a prolonged spell without rain (week or more) you should water gently but deeply once a week. As a rough rule of thumb apply approx 10 litres per metre squared of soil area. Carry out this watering in the morning and try to avoid splashing the leaves, watering the soil instead.
One option to conserve soil moisture in a dry summer is to spread a one to two inch thick layer of grass clippings on the soil around the plants. Ensure the clippings are weed killer free and that they do not directly touch the plant stems.
At about the fifteenth week after sowing and while plants are growing strongly you can apply a second application of a well balanced fertiliser. Although not essential, a further scattering of Growmore or fish blood and bone can increase the vegetables vigour and make them less susceptible to plant ills. Once scattered the fertiliser should be lightly scratched into the soils surface followed by gentle but deep watering of the soil.
Should any flower stem/heads start to appear you should snap these off. Take note of which onion plants these appeared on and use these in the kitchen first.
Pests and Diseases:
Bird attack tends to be one of the main pest problems encountered by onion set growers. These pests tend to pull up young setts root and all. Bird protection in the form of netting should be used. Fine netting draped across a few twigs will provide protection against these birds. This protection measure is especially important if pigeons are a problem in your area.
Other troubles of onions include…
Stem and bulb eelworm,
White rot/Mouldy Nose
You should not encounter major problems with this fungal disease on leeks if you follow the soil preparation, plant spacing, feeding and pH rules mentioned earlier. With any cases of this disease, when you are watering you should try to avoid splashing the leaves which can spread the fungal spores.
Harvesting, when and how:
Pull your leeks as and when you need them. Grasp the stem and carefully lever out the root from beneath with a hand fork, then shake off the soil.
For medium term storage (up to a month) place any harvested leeks in the salad crisper compartment of your refrigerator. However, to be quite honest I find lifting early to be a waste, as leeks can actually sit within your soil until needed. You can leave them in the ground over most winters as they will tolerate a moderate frost (-2° to -5 ° Celsius). Left in the ground they can be dug when required.
Leeks are really versatile in the kitchen. Cut rounds of their thick white stem can be added to stir fries or used as a boiled vegetable. Cut smaller they can be one of the main constituants of soups, for example cock-a -leekie soup (chicken and leek broth), or you can serve them up as a side dish when sautéed. The milder forms of leek can even be used raw in salads with shredded cabbage.
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