Growing hostas

from seed


Growing hostas from seed

This absolutely should be on your to do list

You must try this at least once.  The waiting after sowing, just to see the first little green dots appear. after that the tiny leaves that start to unfurl and grow, green, yellow, blue, maybe even variegated, possibly with a red petiole.  The patient waiting for the shape of the leaves to show and, in the end, being able to admire your very own new hosta, unique in the hosta world.  With a little bit of luck (or, preferably, a lot) and, some basic skills you could end up with, one of your babies might be even worth it to be registered as a new cultivar.

The sowing part is just a technique, and it's very easy. 
I'm a relative newbie to it, and the first results are simply overwhelming (at least, they are to me).

It's the hybridizing that's the challenging part.

What do you need ?

Not much:

  • seeds
  • sowing medium
  • water
  • containers
  • an identification system
  • preferably: an environment with a very humid atmosphere


A rather important ingredient when you want to sow hostas.

There are different ways to get seeds:

  • buying
  • getting them for free
  • harvesting seeds that formed without human intervention (OP seeds)
  • harvesting seeds that are the product of your hybridizing scheme.

If you're a newbie to sowing, and you can get seeds one of the first three ways, I'd advice you to read the topic on hybridizing first, especially the part on the inheritance of traits. This will give you an idea what you can expect, and some idea about which seeds to get and which aren't worth bothering.

Make sure the seeds are clean; every remaining impurity can be a source for moulds after sowing.  You could even remove the wings of the seeds.

Harvesting seeds

After blooming, a seed pod will form when fertilization was successful.  About six to eight weeks after pollination, the seeds are ripe.  Usually the pod splits open and shows its black seeds.
If they don't open, give them a hand.

The pods I want to harvest, I put in a paper envelope, with the name of the pod parent (mother) and the pollen parent (father) written on it.  I store all the envelope in a large shoe box that I store in a cool, dry place.  This way, maximum fertility is guaranteed for at least six months.  If you want to store the seeds for a longer period, put them in the freezer, in an airtight plastic container, like an old film roll containers.  They will remain fertile for years.

The pods stay in the envelopes for a couple of weeks, until they are dry.  After a couple of weeks of drying I remove the seeds from the pods, with a pair of tweezers, or I call in the help of the kids, with their tiny fingers.  The fertile seeds are black or dark brown, with a small swelling at the base (the germ).  Flat, white or light brown seeds and other funny bits are removed meticulously.  You could even remove the 'wings'.  This diminishes the chances of contamination and makes the seeds more manageable.

Sowing mixture

I don't call it sowing soil, because most of the sowing mixtures are soilless.
Don't ever use garden soil if you can avoid it; the results tend to be very disappointing.

You can get special commercial sowing mixtures, even in small quantities.  These usually are very good.

Characteristics of a good sowing mixture:

  • it doesn't have to be very rich in nutrients.  Never add any solid fertilizer, like dried manure in pellets.  The risks of moulds is very real.  As the seedlings get bigger, it's better to give them a very weak solution of liquid fertilizer; 
  • moisture retaining and free draining;  it should be able to contain enough water and air, and should be easy to get wet again after drying out
  •  free of pathogens; either sterilize your mixture, or buy a sterile mixture.  An infection of moulds or pathogens can ruin your seedlings very fast.  Sterilizing can be done in a micro wave oven; heat the wet sowing mixture for about 10 minutes.

I've switched to a soilless, sterile coco based growing medium.  It comes in the form of a compact brick, that is soaked in water.  It's absolutely free of impurities, has the ideal pH for hostas, it keeps airy and doesn't degrade fast.  Just have to add some filtered and boiled rain water, and I'm ready to go.

You can see it here


Not to much lime (soft water), and, of course, free of impurities, pathogens and moulds.  Boiling it is a good practice.

Sowing containers

Each batch of seedlings gets its own container, not to small (dries out fast) and not to large (at the latest after couple of months it's time to prick out the seedlings anyway, so they don't need a mot of soil).

Make sure there completely clean and free of germs.  Just wash them up and let them soak them in a bleach or Lysol solution for 10 minutes.

Identification System

This may sound very "professional", but it's simply a way to identify every sowing container.  I use plastic tags and a weatherproof marker. 

Make sure you have enough labels for every remaining seedling after pricking out.  At this stage, I often use a white marker to write on the black plastic pots.

Air under tension

The containers are placed in an sealed environment where water and air can't escape.  This can be achieved in many ways:

  • put individual containers in a transparent plastic bag and tie a knot.  Put some wooden sticks in the pot, to create a little greenhouse.
  • place the containers in a little indoor greenhouse with a transparent cover.
  • put the seedlings in a cold frame or a (small) plastic tunnel that you keep shut.

Advantage: the little ones will grow better, because the temperature rises a bit and the moisture level in the soil and the air is maintained better.

Especially when using this incubation method, it's critical to work as sterile as possible (containers, water, growing mixture, etc.)

Let's sow

Here the fun bit starts

First prepare the sowing containers and the labels.  Sprinkle the seeds on the surface and cover with a thin layer of soil , just enough to cover up the seeds completely.  I know covering up the seeds isn't absolutely necessary, but it prevents the tiny roots from lying on the surface.

How many seeds per pot ?  This depends on a few factors:

  • the amount of soil available: a lot of seedlings in very little soil is bound to give problems if you want to keep the seedlings in their first container for a bit longer: the soil will be exhausted very quickly, so extra feeding is required; the quality of the soil will deteriorate very soon and repotting is necessary.  That's the reason for my advise not to use very tiny sowing containers.
  • the time of sowing and the available space: if you start sowing very early (like November) and your space is limited, don't put to many seeds per pot.  If you sow the seeds really close together, you may have to repot them as early January and grow them on indoors.  This can take up a lot of space !!  
  • if you start sowing later on, January or later, you can sow more seeds per container, as long as no repotting is required for as long as the seedlings are grown indoors.
  • if space is no problem, you can do whatever you prefer.

Label everything clearly.  You'll regret it if don't.

Place the containers in a tray and give plenty of water (water from below, until the soil is completely soaked).  The soil should at all times be (and remain) moist, not soaking wet.  Hosta seedlings love a lot of water, but the tender roots need air as well.  That's why it is important to use a good, free draining sowing medium, with a good balance between water and air.

When you use an environment with air under tension, put the hood in place, completely shut.  To start the germination going, heat is very important.  A very much used technique is putting the trays on top of the fridge, where the temperature tends to be a couple of degrees higher.  When sowing outdoors, a place in a cold frame or a greenhouse is much appreciated.

Germination starts after about 13 days.  While the seeds are germinating, no extra lighting is required.

In my experience the germinating process is speeded up very much if you cover up your sowing installation and make it airtight.  This will create a very humid, almost tropical atmosphere, ideal conditions for germination.  In my 2006-2007 sowing experiment, the first seedlings showed up after 3-4 days, and in two weeks time most of the seeds had germinated.  There is one major drawback: this humid atmosphere is ideal for fungi and moulds as well, so be sure to start from a sterile sowing mixture and keep a fungicide at hand.

Nursing the newly born

As soon as most of the seedlings are showing, 10 to 13 days after sowing, it's time to add your artificial lighting.  You can leave the lights on 24/7 if you like.  This will speed up the growing process considerably.  Keep in mind that even TL lights produce some heat; your seedlings could get burned.

Watch the seedlings grow.
Check on your babies every day.

After two weeks, I start feeding them with a very low dose of a weak liquid tomato fertilizer (a tip from Jim Spence, AKA Mr. Leaf mould, who grows enormous seedlings), because the coco sowing medium has almost no nutrients in it.

Picking out - first selection

Depending on the size of the sowing containers, the number of seedlings in them and the time of sowing, you'll have to decide when to pick out the plants in a larger container.  I start potting up plants individually when almost all of the seedlings in a container have four real leaves. 

Be sure to have enough labels for every remaining seedling.  If you don't keep the correct name or cross with your seedlings, you'll end up with a bunch of unnamed, unidentifiable young plants.

This is also the time to do the first culling.
When you start sowing hostas, you should set yourself a target.  What kind of new hosta would you like to grow ?
Now is the time to dispose of all the seedlings that don't fit your scheme, which is easier said than done.  If you're going for streakers, the job is fairly easy.  A 4 leaved seedling that doesn't show any streaking never will, so all the single colored ones have to go.  If, like I, you're into solid colored plants, the task is far more difficult, since color, leaf shape, petiole color in a mature plant can only be fully judged in a mature plant.  Still, choices have to be made, and there is always the possibility that you're throwing away a seedling that would have grown into a real beauty (luckily you'll never know).
It may seem hard, but it needs to be done.  There is no point in hanging on to large numbers of almost identical green seedlings, and the less plants that remain, the more time you can invest in the survivors. 

Moving the seedlings outdoors

Although we have spells of frost until early may, my seedlings are moved outdoors into a cold frame at the end of march.  The cold frame protects them at night and is opened during the day to harden off the seedlings.

This way the temperature is high enough to prevent the young seedlings to go into dormancy.

Evaluating the plants

At least once a year you'll have to evaluate them, and get rid of any plant that doesn't live up to the standards you've set.  You'll have to judge color, plant shape, leaf shape, substance, growth rate, quality as a garden plant, health, slug resistance, breeding potential and much more. 
There is no use in hanging on to plants that aren't an improvement over any existing hosta.  No one is waiting for yet another thin leaved green hosta with a white edge.  As your plants get older, they will take up more space and more of your time.  After 5-7 years, a seedling will reach maturity, and a final judgment can be made.  If you've been hard on yourself the previous years, this shouldn't be to hard any more.

Sowing outdoors

This is much like sowing indoors, bur with far less fuzz.

When ?

Whenever you like: spring, summer, autumn (winter sowing, the containers remain outside in the cold, the seeds will germinate whenever they feel like it in spring.

Other recommended links on growing hostas from seed

The Hosta Seed Growers

A number of hosta growing addicts set up this web site.  Available are general tips on growing hostas from seeds, a who's who, a page with seedling pictures for every grower, links to other great sites, etc.  Great stuff for the die-hard hosta grower.

Hosta seed growing tips on the Hosta Library

Bob Axmear's very informative pages on indoors, outdoors and greenhouse seeds growing tips