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| Asparagus |
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This perennial crop takes two years to establish and has only a short cropping season, but it is well worth growing for its delicious shoots (spears)
The key to a good crop is in the 'soil preparation'
Asparagus prefers a well-drained, neutral to alkaline soil.
The best crops are produced on light, sandy soils, if the soil is decidedly heavy, work in plenty of well-rotted manure.
On heavy soils that tend to be waterlogged, asparagus is better grown in a raised bed.
Prior to planting out, fork out all perennial weeds (they are difficult to remove once the crop establishes), and dig in plenty of organic matter.
Apply a base dressing of a general fertiliser prior to planting.
With established plants apply a top dressing before they start into new growth and after harvest.
Once established, a bed will continue to produce crops for many years, and the size and quality of the shoots improve each year.
Plants can be raised from seed but can take three or four years to reach cropping size, and as the most common method of growing asparagus is to purchase one-year-old male crowns
Week 12; Asparagus seed can be sown into individual 90mm (3½”) pots and germinated at a temperature of at 13-16°C (55-60°F).
Emerging seedlings should be hardened off before being planted out.
alternatively; Purchase 'crowns' (one-year-old plants), plant as soon as possible after delivery to prevent the fleshy roots from drying out.
New bed culture;
Week 16; Plant out crowns
Dig a trench 300mm (12”) wide and 250mm (10”) deep
nb. Asparagus plants can be either all-male F1 hybrids or a mix of male and female plants.
Hybrids are more vigorous and generally higher-yielding.
Form a 100mm (4”) high ridge of good soil along the base of the trench, and plant one year-old crowns, 300mm (12”) apart, spreading the roots evenly on either side of the ridge.
Cover the crowns with 50mm (2”) of soil and gently firm and water them in
During the growing season, continue to cover the crowns until the natural soil level is reached and ensure plants are kept well watered.
Week 20; Plant out Asparagus that has been raised from seed 50mm (2") deep
The first asparagus spears can be cut two years after planting.
In this first year, only crop for a maximum of six weeks but in subsequent years this can be extended to eight weeks.
Week 40 to Week 20; Form a 1200mm (4ft) wide bed, ideally in a spot protected from north easterly winds, and dig in a copious amount of well rotted farmyard manure or homemade compost into the topsoil.
Established bed culture;
Week 16 to 18; To ensure long-stemmed blanched spears ridge up the rows with a draw hoe, and top-dress with a general fertiliser at the rate of 60gms (2oz.) per sq metre.
Week 20; Cropping can usually begin in the second year after planting.
Cut the shoots when they are 100-150mm (4”-6”) tall.
Make the cuts approximately 50mm (2"0 below ground level, taking care not to damage any other stems.
nb. With relatively new plants, restrict cutting to about four spears per plant until the bed is firmly established (usually three years or more from planting)
However; with long established plants; harvest all the spears, including thin and bent shoots, as this will help to promote new growth.
If they cannot be used immediately, stand them in jars of fresh water to prevent their rapid deterioration.
n.b. After mid-June leave any further stems to develop until autumn.
Week 26; keep beds free from weed.
Summer hoeing will help to suppress annual weeds, and also prevents surface compaction of the soil.
Water beds liberally throughout summer.
Watch for signs of the orange and black asparagus beetle and their grubs otherwise they may strip the 'fern' (foliage).
Week 28; Apply a nitrogen fertilizer such as nitro-chalk at a rate of 30 gm (1 oz) per sq m.
Apply a 50-70mm (2"-3") layer of well-rotted manure, which will also suppress weeds.
Week 30; Remove unripe berries to prevent a mass of unwanted seedlings next year.
Berry formation also diverts energy from growth.
Tie the 'fern’ into canes with soft twine or twist ties if the plants are exposed to strong winds.
Week 36 onwards; when the ferny foliage begins to change colour, it should be cut back to within 25mm (1”) of the ground, and burnt, again to prevent berries of female plants producing inferior seedlings.
Week 40 to Week 20 the following year;
Select a site protected from north easterly winds.
Prepare a 1200mm (4ft) wide bed by digging in well rotted farmyard manure or homemade compost into the topsoil.
Week 42; Crowns may be forced to extend the season or for exhibition purposes by lifting four-year-old or older crowns and placing them under the greenhouse staging.
Cover the crowns with 50mm (2”) of potting compost.
Keep the crowns at a temperature of 16C (60 F), and in moist soil.
nb. After forcing, crowns should be discarded, but may be replanted in the permanent bed after harvesting.
They generally take a year or two to recover and produce worthwhile crops again.
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