For most vegetable varieties grown by amateurs, choosing the wrong variety or growing them incorrectly causes only short term annoyance, easily remedied and a lesson learned for next year.
Not so with asparagus. If I were to say to you that building an asparagus bed takes as much effort as a planning a wedding I wouldn’t be far wrong. Planning the location, choosing the right variety, preparing the soil, planting the crowns, providing supporting structures for the ferns, keeping control of pests and weeds, feeding the soil and then the agonising wait for three years before you can eat your first spears can be off putting but as an asparagus bed can last 20 years which is longer than most marriages it’s worth the effort of doing it right first time round.
Why would you do it? Quite simple, like sweet corn, freshly picked asparagus, cooked within minutes of picking makes supermarket offerings taste like cardboard and once your bed is planted, with a bit of TLC every year, it will provide months of asparagus every year for years to come for much less money than it would cost you to buy. So where you’ll you start?
Locating your asparagus bed
An idea situation for asparagus is in full sun or dappled shade and preferably not exposed to high winds. The site should be cleared of all weeds and especially perennial weeds. If you have any vicious perennials like marestail or bindweed on the site you should not start until they have been fully cleared and you are sure that they will not return.
The most important thing is drainage. If you are on heavy clay dig in plenty of grit, and you may even consider raised beds. All sites will need incorporation of plenty of organic matter.
12 crowns should give roughly fifty servings over eight weeks.
Below is a list of the most commonly available varieties that can be bought as plants in the UK. You can grow from seed but you will have to wait another year to eat the asparagus.
You would normally purchase one year old crowns in the autumn/winter which will be delivered in spring. All male varieties will in general not set seed so waste less energy and make more robust plants.
Pacific 2000: An early season (Early April) variety with vigorous uniform stems. It has a good reputation for taste, although it doesn’t pack as big a punch as some of the later varieties. It can be eaten raw but some find it a little bitter. Contains higher levels of anthocyanin.
Gijnlim F1: An early (April) high yielding all male hybrid with slender spears and good flavour. This is my favourite variety for flavour with almost olive oil notes. It can be used for forcing. It is a little less fussy about soil conditions and has an RHS award of garden merit at the time of publishing. Contains higher levels of anthocyanin.
Mondo F1: All male mid season (Mid April) variety. I’ve not grown this variety but descriptions range from excellent taste to insipid. Generally considered to be very tender.
Backlim: A midseason (May June) all male hybrid with chunky spears that crops over a long period. Can be blanched for white asparagus. It has an RHS award of garden merit at the time of publishing.
Pacific Purple: A purple mid season variety (mid April to June). I’ve not grown this variety so cannot vouch for accuracy but it’s purple colour, all the way down, rather than just on the tips indicates it is higher in anthocyanin than other varieties. Catalogues also describe it as exceptionally tender, the best to use raw and sweeter than green varieties. Others don’t rate it so highly, describing it as watery.
Guelph Millennium F1: All male, late Season (Mid May to June) F1 Variety. It is supposed to be more cold tolerant than other varieties so good for northerly gardens.
Before the plants are expected to arrive you will need to dig you trenches and incorporate organic matter. For all soil types you will need plenty of organic matter (well rotted manure or compost), a 50l bag for every metre.
- Dig trenches, 30cm wide and 20cm deep, 50 cm apart.
You might want to hold off on the next part if poor weather is forecast to prevent your soil compacting
- Work in organic matter to the bottom of the trench.
- Cover the bottom of the trench with 5cm of soil
- Make a 10cm high ridge of soil down the centre of the trench. The top of the asparagus crown will sit on the ridge and it’s roots go down either side
When the crowns arrive if you can’t plant them straight away, remove from any plastic bags they may be in and store in dampened compost.
When you come to planting lay the crowns, 50 cm apart, trying to stagger the plants in rows as much as possible. Gently spread the roots out and then cover with the rest of the evacuated soil. Water well and then mulch with an additional thick layer (5cm +) of compost.
You might find it useful to place a small marker close to each crown so you know where they are.
You will need to weed by hand to stop anciently chopping off emerging shoots.
Although asparagus likes a well drained soil they do need water and you should water in dry periods for at least the first few years or when drought occurs.
Plants will reach up to 1.5m. Most people will build a cage with wire supports to stop the asparagus rocking around too much or snapping in the wind.
Do not harvest anything for two springs.
From about May you will need to pick off the dreaded asparagus beetle, larvae and eggs. Beatles are usually red with black spots or checks, sometimes with some white. They are slender and just under a centimeter in length. Larvae are are greeny brown up to 5mm in length. Eggs are 1-2m in length, black and very fine, they stick off vertically from the fern. Larvae can’t crawl very far so I pick them or the eggs off and put in the compost heap. The beatles can fly so I’m afraid they get knocked off in to a small plant pot and dispatched.
Every spring re mulch with 5cm of compost and give a dressing of blood fish and bone meal.
When you can finally harvest, start to harvest when the spears are about 10-15cm long. Cut the spears with a sharp knife just below the soil line. You can cut for 6 weeks. When your bed is fully established some may cut for up to 8 weeks.