Growing asparagus at home isn’t a crop, it’s a relationship. An asparagus bed can last for up to 20 years so it is little wonder that those considering the endeavour want to do a bit of research before making their bed and lying in it. And when doing their homework, one of the first issues that would-be asparagus growers come up against is the complicated sex life of asparagus. Well it seems complicated but it’s really quite straightforward. In fact antics in the asparagus bed are more like those in the human bed than the plant world – not that that is necessarily always straightforward, but at least it’s understandable.
You see unlike most plants, asparagus plants are either male or female and, a bit like us, the female plants produce the fruit. In their case, bright red berries on the ferny foliage denotes the plant is female. So we get a lot of questions from people wanting to know how to tell the difference between male and female plants and do they need one of each?
The simple answer is that, until they produce ferns with berries you can’t tell them apart but the good news is you don’t need one of each. We don’t eat the fruit of asparagus, we eat the new shoots – and both sexes produce these. The fruit is actually a bit of a nuisance. Male plants that don’t fruit start producing spears earlier in the season and produce between 10 – 20% more shoots than the female plants. Probably because they don’t have to spend energy raising the kids. The berries from the female plants can also self-seed in the bed, clogging things up. But the story doesn’t end there…
Asparagus is one of the oldest vegetables in human cultivation and so over the centuries growers and breeders have kept a keen eye on it and selected varieties for different characteristics including colour, longevity, size, disease resistance, climatic tolerance and even sexual orientation. Yes as it turns out not all asparagus plants are male or female. In the 1960’s Professor Howard Ellison from Rutger State University, New Jersey discovered some hermaphrodite asparagus plants which he self-pollinated and through further breeding created hybrid varieties that produced all male offspring. These varieties often have “Jersey” in the name and are marketed as all male producing.
To confuse matters further home gardeners can also choose from a range of modern hybrid varieties resulting from arranged marriages. These hybrids still produce both male and female plants but may outperform their open-pollinated heirloom cousins in certain departments like disease resistance and longevity.
Confused yet? Well I will admit all this can make choosing a variety of asparagus to grow in your garden quite baffling. Is that fancy violet Italian renaissance model a good idea or should you opt for plain American Mary Washington? Is a same sex marriage from New Jersey going to be any good or should you go for a performance enhanced Pacific 2000 hybrid, with girls included but bred for NZ conditions?
Asparagus eh! Who would have guessed it was such a hot bed. Personally I’m normally all for open pollinated varieties so folks can save and sow the seeds again and again – but when it comes to asparagus – how many beds are you going to have? So I opt for the modern hybrids. The Pacific 2000 is such a good performer that I don’t mind the odd girl in there bringing down the average and I know it does well in NZ conditions. I’m not against the all-male hybrids but I’m not sure how well they do here.
Some tips on Growing Asparagus
- There is a common myth that a bucket of salt water will do wonders for your asparagus patch but I can vouch for the fact that a bucket of alpaca poo or any well-rotted manure will be more welcomed. Just because asparagus is salt tolerant doesn’t mean it loves it. I mean I’m brussel sprout tolerant.
- If you’re growing asparagus from seed, grow the plants in individual pots for the first season and then plant them as one year old crowns the following spring when the soil warms up.
- Prepare your asparagus bed well in advance of planting. It’s going to be there for a while so it is worth putting time in up front to get it right. Asparagus likes a good free drained soil and plenty of well rotted compost and manure. It is a good idea to dig your row around 30cm deep and the same width and fill the bottom with a mixture of sandy soil, compost and well rotted manure.
- Asparagus likes a slightly acidic soil so if your soil is really acidic add a few handfuls of lime to make it more palatable, if it is more alkaline add some garden sulphur and mix it in well before you plant your crowns.
- Place your crowns in the trench in a two rows spacing each crown 20 cm apart and cover them up until the trench is around 10 cm from the top with more of the soil and compost mix. In the first winter fill in the rest of the trench.
- Leave your bed the first year without picking it. In its second spring you can start picking and you’ll get a good 3 or 4 weeks of picking spears before it starts to run to ferns. From your third year on-wards you should get a harvest period of around 7-8 weeks from your bed.
- A well tended asparagus crown from modern hybrid should produce a pound (450g) of asparagus a season so allow 4-6 crowns per person depending on their love for the stuff. If you’re growing the older heirloom varieties allow more crowns per person.
- Keep the water up to your bed during the growing season and pick daily as it becomes fibrous if left to grow bigger.
- Eat daily too as once picked it starts losing its natural sugars. Purple asparagus is sweeter and more tender and is good to eat raw sliced in salads
- White asparagus can be grown by covering purple asparagus with black plastic or mounding it with soil. It is very sweet and popular in Europe.
- You will know when to stop cutting the spears as they start getting spindly. Don’t over cut it – leave the spears to go to ferns as these provide food for the crowns to produce next years crop.
- When the ferns start to die off in autumn cut them back to just above ground level and cover them with a good layer of compost for the winter.
Now all you have to do is make the hollandaise!
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