Asparagus seed saving

I have grown asparagus (Asparagus officinalis) from seed many times.  Growing from sed is fiddly and takes time.  It takes a few years to get a crop when grown from seed, which means that many people prefer to buy year old crowns instead.  

Many heirloom asparagus varieties have a superior flavour and texture, but other than a few varieties nowhere sells plants.  I buy seed of these harder to find heirloom varieties from respected companies, grow them out for a year or two, and sell the dormant crowns.  I don't tend to save seed myself because I cannot ensure pure varieties.  

On average from bought seed I most often tend to get about 30% germination.  Occasionally I get 100% germination, other times I tend to see 10% or frustratingly sometimes even zero percent germination.  I believe this is probably due to the age of the seed, with poor germination from older seed.  

Asparagus seed saving

Asparagus plants are dioecious, individual plants are either male, or they are female.  Unless you pay for some form of genetic testing, you can't tell them apart until they flower.  

Large farms only grow male plants.  If they have any female plants, these will drop seeds, and the seedlings eventually choke the beds making all the plants unprofitable.  

Sadly, home gardeners have been told to remove female plants (due to seedlings) for so long that they think female plants are inferior.  This is not true.  Female asparagus plants are proven to produce longer, fatter, more tender spears.  Home growers probably prefer female plants as they produce longer, fatter, more succulent spears, and many home gardeners can devote the time needed to either remove berries or remove seedlings.  

Asparagus seedlings germinating

Many purple asparagus plants are tetraploid, and many green asparagus varieties are diploid.  I wonder if I could cross them to produce seedless triploids.  If this was the case there would be no reason not to grow female asparagus plants.  I think crossing them may be a project for a future year, or a project for someone else to try.  

Purple asparagus is sweeter than green, and when forced to be white it is even sweeter.  In this country, most of the purple asparagus is from unnamed varieties.  I was buying seed from purple asparagus and growing it out to sell crowns.  Seed is expensive, which meant my plants were expensive.  Buying seed also meant that if the company sells out, or if they send me old seed with low/no germination, I could not grow and sell any plants.  

The past few years I have been unable to buy any purple asparagus seed.  I have a few purple asparagus plants, some are male, others are female.  I decided to allow them to flower, save seed, grow some, and see if the seedings are purple.  If they produce purple seedlings then I can save my own purple asparagus seed.  

Purple asparagus spears

As there are not many pages on the internet explaining how to save asparagus seed I thought I would write a post about how I did this.  

I am only saving seed from purple asparagus because it is not a named variety.  I am not certain that any of the green named varieties will come true from seed.  For this reason any plants I sell from named varieties will be grown from seed bought from reputable companies, and not from seed I saved myself.  

To get seed you need mature asparagus plants.  As mentioned, asparagus plants are either male or female.  You need both in order to get seed, or at the very least you need a female plant and a male nearby that can pollinate it.  

Purple asparagus spear next to green for comparison

Asparagus sends up their spears, they fern out and look nice and fluffy, if the plant is old enough and healthy enough it will flower.  Flowers are uninteresting and small, many insects (and possibly wind) will gladly pollinate them.  

Not long after the flowers die off the female plants will produce little red berries.  Please don't eat these, they are mildly toxic.  I am told that birds can eat them with no ill effects.  The berries turn red and look nice.  

Asparagus berries

asparagus berries

They produce a lot of seed

Once the majority of the berries are ripe like in the photos above, I pick them off the plant.  I hadn't realised before, but some asparagus is slightly thorny after it ferns out, so picking berries can be painful and time consuming.  

The asparagus plants produce tremendous numbers of berries.  I pulled them into a container.  I had planned to collect all of the berries, but there were so many I only collected them from one or two fronds.  

You may notice in the photo that there are a lot of little insects and spiders and things in among the chaff.  I grow everything organically, meaning this is unavoidable.  I left the container for an hour or so while I did something else, this gave time for the tiny critters to climb out and go somewhere else.  

Asparagus produces a lot of seed

Once I had the asparagus berries I could squish a few berries, get their seeds, and I would be good to go.  But what do you do when you have heaps of berries?  

Each berry contains between one and six seeds.  There were many hundreds of berries in my container.  I could not squish each berry and carefully remove the seeds.  

I went through and removed any berries that didn't look ripe.  Anything green was thrown away.  Perhaps the seed would be fine and the seeds would still germinate, but I had enough that I didn't need to risk it.  

I added some water to the container, got a potato masher, and squashed everything.  It made a mess, it smelled bitter (yes, you can smell bitter, if you collect asparagus seed you will know what I mean), most of the fruit pulp floated, while most of the seeds sank.  This made life easier.

Asparagus berries

Once I had enough of mashing asparagus berries, I carefully tipped off  most of the pulp.  Then I added more water, tipped off the pulp.  I did this a few times to remove most of the pulp while retaining most of the seeds.

One thing I was not ready for was that seeds would float after they touched air.  If the seeds touched the air they would get a little bubble, and this would make them float.  If I stirred the mix, the seeds would lose their little bubble, and they would sink.  Some seeds always float, presumably they are not good seeds and they were also tipped off.  

After I tipped off as much water as I could, as well as pouring off the pulp and floating seeds, and left the remaining seeds to dry in the shade for a few days.

asparagus seeds with a little pulp

Asparagus seeds, leave to dry a few days

Once the seeds were dry I put them in a little bag.  There is still a little chaff in there, but that won't affect germination.  

As you can see, I have a lot of asparagus seeds.  I could have collected a lot more seed, but the effort involved is not worth it as the seed loses viability relatively quickly.  This little bag of seeds is now in the fridge.  

From here I had a lot of asparagus seed to plant.  I was curious to see what percentage germinated, and to see if fresh seeds did germinate easily without any stratification or other treatment.

To test the germination rate I got my daughter to count out 100 seeds.  I planted them into a pot of soil and recorded the results.  Not surprisingly, with fresh seed the germination percentage was really high.  No cold stratification was needed, fresh seeds were simple and quick to germinate. 

I really should stop this blog post as it is getting a little long, I will try to write another post on the results of the seed grow out.  

If you are interested in buying year old dormant crowns over winter, or buying some purple asparagus seed, I may list it on my for sale blog page.