All about asparagus
This is one of the earliest and
tastiest plants we can grow in the garden. It has been harvested in
Greece for 2500 years, the word meaning ‘stalk’ or ‘shoot’ in Greek.
There are many different species of Asparagus and several wild ones can
still be seen growing in poor and barren soil in Greece.
Garden asparagus, Asparagus officinalis, grows wild in large
areas of the United States to which it was originally introduced. Many
people forage for it in the spring and it has become an iconic wild
plant. In southern England this species readily naturalises on grassy
heaths and dunes, mainly by bird-dispersed seed.
The native asparagus Asparagus officinalis subsp.
prostratus grows in a few places on sea cliffs in south west
England, Wales and Ireland. It is rare and declining and should no
longer be picked.
Growing Asparagus
It is possible, and much cheaper, to grow asparagus from seed, rather
than buying crowns, but it will be 3 years before you can enjoy your
first proper picking. Germination takes at least 3 weeks and, though
initial rates are good, it can be difficult to successfully grow it on.
The wastage rate for the amateur gardener is very high. We therefore
recommend buying one year old crowns, they are more likely to grow well
and you will only have to wait 2 years before picking. Properly looked
after, crowns should provide a good annual six week harvest for up to 20
years so you need to carefully choose the place where it will grow and
properly prepare the site.
Preparing your Asparagus
bed
When planning your site, choose a
sunny spot with free draining soil. Crowns will rot if they sit in damp
or water logged conditions. Remember established asparagus ferns will
grow to about five feet (150cm) after you’ve finished cutting the
spears, so plant them where any shade they cast won’t matter. Arthur
Simons, writing in 1945, thought that “the average family will need a
bed 5’ wide x 40’ long with 50 crowns”. Perhaps we won’t need quite so
much.
If you want a good, steady supply of fat spears, the bed will need to be
carefully prepared. The plants will not tolerate weed competition, so a
large area round about must be kept clean with no perennial weeds. The
main root system grows very close to the surface and it is easily
damaged, so it’s important that weeding should be done by hand and that
no tools are used.
Asparagus
thrives in soil with a pH of 6.5 – 7, so you may need to add lime,
preferably in the autumn before planting. Clear an area one metre wide
and whatever length you want. In the centre, dig a trench 30cm wide x
45cm deep, adding a generous mix of garden compost, well rotted manure
and soil. The roots of well established asparagus plants will go down to
a depth of 4’ (120cm), so it’s important that the soil should be good
and rich to a good depth. The crowns are shaped like a spider, so when
planting them, make sure the roots are not in contact with the rich mix
by adding plain soil on top of it. Make a central ridge 7-8cm below the
final soil level and place the crowns on this ridge. Make sure the
roots, the spiders’ legs, are carefully and evenly spread over each side
of the ridge. The planting distance between crowns is 45cm. Cover the
crowns with 5cm of soil, and broadcast seaweed meal fertiliser. Seaweed
is much the best fertiliser to use as asparagus is a coastal plant and
so appreciates seaweed’s rich supply of vitamins, amino acids and trace
elements, providing all the plant needs without encouraging too hasty
and pest attractant growth. Draw more soil into the trench as the ferns
start to grow until the centre is level with the sides.
Looking after your Asparagus
The ferns will appear within a few weeks and must be left to grow freely
throughout this first season. Keep on top of the weeding, cut all the
ferns back in the autumn and give the soil a light seaweed meal
dressing.
IN THE FOLLOWING SPRING, add good home made compost along the small
ridge. A light sprinkling of woodash can also be valuable. After the
plants have been growing for about a month, it will be possible to cut
one spear, but only one, from each crown to taste. In the Autumn treat
the bed as you did at the end of the first year.
If you plant 2 year old crowns, you can cut as described below for year
3 of 1 year old crowns.
DURING THE THIRD YEAR AFTER PLANTING, the fourth from sowing, you can
start to harvest your crop. Start the season by giving the ridge an
additional layer of good compost and woodash, if available.
Harvesting your Asparagus
Cutting asparagus with a sharp knife is a very satisfying experience –
and the knife does need to be sharp to avoid damaging the plant. Cut the
spears at ground level when about 15cm tall. Purists would advise
cutting below the surface to get well blanched spears, but this can be
dangerous as you could damage a lot of tiny spears that haven’t yet
broken the surface. Keep cutting for six weeks, and be sure to cut all
the spears, including the sprue (the thin spindly ones).
You will then need to let the growing ferns feed the crowns. When
growing well, these beautiful ferns will reach 5’ (150cm) so will need
support if they are not to flop and break. Old Christmas tree branches
or pea sticks make excellent supports and pole and twine also work well.
They form an impenetrable barrier and weeding can become difficult when
they are fully grown.
When the ferns start to die back, cut them to ground level and shred or
compost the foliage. Finish off by spreading a light seaweed meal
dressing and think of next year’s delicious treats!
SUBSEQUENT YEARS – Feed the crowns in early spring and again in autumn.
Cut all spears for six weeks only and then allow the ferns to grow.
Finally cut down and remove when they start to die back in the autumn.
Varieties to choose
Several varieties of asparagus are readily available to buy as crowns.
The most common, and therefore the widest range, are one year old
crowns; you tend to have less choice of two year old crowns. Because
seed is slow and less popular there is also a smaller range of this.
The most common variety is Connover’s Colossal which produces
green spears of medium thickness and good flavour. It is reliable and
prolific.
Grolim, an F1 variety, is also commonly available. It has thick
spears with tightly closed heads and is very uniform and straight.
Because it is an F1 it is more expensive.
Backlim is also an F!. It is an all male variety so you won’t
get any self sown seedlings. It is a later producer and has good yields
of thick smooth spears. It can be grown as green or white asparagus.
Crimson Pacific is a high yielding, mid season cropper
producing super-sweet, tender spears with a low fibre content. It can be
grown as purple or white asparagus.
Always keep newly bought asparagus crowns moist, but not wet.
They will suffer and may die if allowed to become dry.