Hybridizing

Hybridizing

Contents

Why hybridizing is better

To grow hosta seeds there are two ways: open pollination and hybridizing.

With open pollination, you let nature do all the work for you.  The pollination is done by bees and other insects. 
All you have to do is wait until the seeds are ripe and get sowing.

Hybridizing means raising plants from seeds that are the result of hand pollination, in order to breed plants that are different from and/or better than existing cultivars.  The hybridizer decides on the mother and father plant, and thus has a large impact on the final results.

Why go for hybridizing ?  Let's face the facts: raising hostas from seed is fun, but, if you want to do it right, it can be a lot of work.  And when, in the end, the results are disappointing or mediocre at best, it's a waste of time and money.

This is almost always the case with open pollination.  The chances of getting a seedling that is really special are very limited.  Most of the seedlings, if not all of them, will be worthless as they are no improvement over existing cultivars.  Another disadvantage is you will never see crosses of plants with a different flowering period. 

Hybridizing on the other hand is no guarantee for success, but the odds are infinitely better. 

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My views on hybridizing

Hybridizing hostas is much, very much more than just a technique.  I consider it to be an art craft. 
Often people just start making as many crosses of whatever plants they find attractive and happen to have in their collection.  In the process of becoming a good hybridizer this is an important stage, since you're learning a lot about the way certain traits inherit (that is, if you keep record of the results), but in my humble opinion, this isn't hybridizing.  You're just an improved bee.

To become a master at hybridizing:

  •  you must be able to perform the technique of hand pollination (easy);
  •  you need a good knowledge of many cultivars and species: properties, what were the parent, which offspring do they have themselves (harder);
  •  you need a good knowledge on inheritance of hosta characteristics and properties (color, shape, substance, texture, growth rate, sun and slug resistance, ...) (even harder);
  •  you must have some artistic gift (some do, some don't);
  •  you must be able to plan your project (not difficult,  but requires discipline and vision);
  •  experience is a huge plus.  Much of the knowledge and skills mentioned above, isn't documented, and can only be acquired through your own experience just takes time).

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Hand Pollination

The hosta inflorescence

For those who aren't familiar with the build of a hosta flower, this picture.

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A technique for hand pollination

Not hard at all.  Each hybridizer has some tricks of his own. 

There are three base requirements:

  • you have to prevent pollination by insects;
  • he pollination must be carried out in a way the largest amount of seeds possible is produced;
  • you must keep the name of pod and pollen plant attached to the correct seedlings during every stage.

The base technique is as follows.

  • Remove part of the corona and all stamens the day before the flower will open, with a pair of scissors.
  • The next day, apply pollen from the chosen pollen parent onto the stigma of the pod parent.  When the pollen doesn't stick to the stigma, either the stigma isn't receptive (yet) or the pollen isn't ripe (dry and fluffy).  When a drop of liquid forms on the stigma, you're too late.
    How to apply pollen ?
    • pick a stamen with ripe pollen en rub the anther over the stigma.
    • take a Q-tip or a fine painters brush to get the pollen and apply onto the stigma.  When you use a brush, clean it thoroughly whenever you change to pollen from a different plant (I use methylated spirit) and let it dry out completely.
  • Label every hand pollinated flower with mini labels, identifying the pollen parent. This can be done by writable labels or with a color based labeling system.  At all time you must know which pollen was used for pollination.  I simply us strings of wool in different colors, one color for every different pollen parent I use.  In my list of pollen parents, I add these color codes (see below).

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How to collect and store pollen

  • Make sure you have enough small storage containers, like micro centrifuge tubes or contact lens cases.
    The contact lens case can be cut in half.
  • Make a list of the pollen parents you are going to use and give each pollen parent a unique number.
  • Mark the containers with the number on your list of the pollen parent you're going to collect pollen from.
  • Cover the scapes you want to collect pollen from with a piece of mesh cloth, so the bees can't get to it.
    Collect pollen in the morning when the flowers are fully open en the pollen appears to be dry and powdery or fluffy.
  • DO NOT put the complete stamen in the container, because the filaments may rot and spoil everything.  Remove the anther by sliding a pair of tweezers or your fingers up the filament, and drop the anther into a container.
    Another technique: collect the ripe pollen with half a Q-tip and put those in a container.
  • Don't close the containers yet.  Bring them inside and place them in a dry room with good ventilation.  Let them dry for 24 for hours before closing the lid.
  • If you intend to use the pollen immediately, it will remain viable for a week.
  • For longtime storage, put a number of containers in a sealed plastic bag and put them in the freezer.  It should remain viable for about 9 years.
  • If you want to add more pollen to a container (it has to dry out for a day first of course), or if you need frozen pollen for pollination purposes, don't let the container thaw out.  Put it back in the freezer as soon as possible.

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Knowledge of cultivars, species en inheritance of properties

Knowledge of cultivars and species

Because hostas are so very genetically instable, it's often hard to predict what the offspring will look like, how characteristics will be passed on.
It's a great benefit if you have a good insight in the origins of cultivars: if you compare parents to their descendents, you can see how some threads inherit.

This knowledge is of great importance when you have to decide which species and cultivars to use in your breeding program.  Once you've decided which characteristics you want your own plants to have, you can start searching for plants that are likely just to pass these properties on to their offspring. It's practically impossible to integrate a species or cultivar you know nothing about in your breeding scheme.

Very little has been published on this matter so far, so you can do plenty of studying on those long winter evenings.

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Knowledge of inheritance of properties

Leaf color

This is the easy part.

Some base rules:

  • to breed hostas with multi colored leaves, the pod-parent (mother) has to be streaked
  • monochrome pod-parents will produce monochrome offspring
  • green hostas produce green seedling, with the odd yellow or blue exception
  • blue hostas, including those with an edge of a different color, produce green, blue and yellow offspring
  • yellow hostas, including those with an edge of a different color, produce green, blue and yellow offspring
  • white hostas, including those with an edge of a different color, produce seedling that are very rarely viable
  • the color of the pollen parent (father) influences the number of seedlings in a color.  Blue x blue will produce more blue seedling than gold x blue, etc...
  • to every single one of these rules, the odd exception is possible

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Scent

Another easy one (to explain anyway).

All scented hostas come from one single species, H. plantaginea.  Compared to every other species, it's almost a subtropical plant.  It originates from the Chinese mainland, where it inhibits a much warmer and sunnier habitat.
These are facts you must take into account if you're planning on using H. plantaginea, by giving it a protected, warm and very light spot.

Another major difference is the fact it's a night bloomer.  This means pollination must be done at night or very early in the morning.

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Other properties

Besides color and scent, there are many other properties that determine the looks and other characteristics of a hosta, like  substance, texture, growth rate, sun tolerance, slug resistance, plant, petiole and leaf size, flower color and shape, undulation of the edge, saw tooth edge, ...

Most of these properties are passed along through the mother as well as through the father. 
Bare in mind that some characteristics are dominant (they will show in the offspring if dad or mom has this characteristic.
Other properties are recessive.  The property will only show if both mom and dad have this characteristic, and the offspring has two genes for this property.  A hosta that has only a single gene for a recessive characteristic, can pass it on to its progeny, but will not show the property itself.
And some characteristics are neither.  If one of the two parents has this feature, and the other hasn't (like scented flowers), the offspring may show this feature very prominent or not at all, and anything in between.  That's why flowers can be stronger or less scented, depending on the amount of scent in the parents.  Even in a single batch of seedlings, the differences can be huge.

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An artistic gift

Some hostas have a very high 'wow!' factor, they strike the hardcore hosta enthusiast and the absolute hosta layman alike as being gorgeous.  Hostas like H. June, H. Sagae, and others.
If you set out to produce an outstanding hosta in that league, you'll have to assemble a number of properties to one esthetically pleasing plant.  And some people have a higher esthetical feeling than others.

Luckily people are often fascinated by the bizarre, the deviating.  Therefore you'll find plenty of hosta lovers that are attracted to a hosta that would look like a ball of lettuce.

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Planning

In my opinion this is the essential condition to achieve good results.  Don't carry along any way the wind blows, but follow a plan, get your activities structured.

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Setting your goals)

First you have to set your targets), the breeding of a plant (or more than one) that has all (or most of) the characteristics you'd like it to have.
And there are a lot of featured to go for. 

First of all, there are a number of basic requirements for every new hosta cultivar:

  •  considerably different from any cultivar in existence
  •  a valuable garden plant:
    • good substance
    • good growth rate
    • reasonably slug resistant
    • not burning to easily
    • ...

Then there is the looks:

  •  plant size and shape;
  •  leaf size and shape, substance, texture,
  •  petiole color, leaf color or colors, front and back (glaucous ?), scape color
  •  scape shape, size and position
  •  flower shape, size, colors), scent
  •  ...

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Determining your means

This is when you'll need good knowledge on existing cultivars and on the way treads are inherited.  A fine pass time for those long winter evenings.
In the end, it will pay of to be extra careful when studying the fertility of cultivars, especially when you plan to use them as pod parents.  Your complete fantastic planning falls to pieces when in the end your much sought after mother plant turns out to be sterile.  And don't forget, there are those hostas that don't set viable pollen.

When you have a "construction plan" for your dream hostas, it's time for the most difficult part: how will you try and realize it ?  You must decide which plants to use as parents. 
Maybe you can use existing cultivars, maybe you'll have to grow a plant first that has most, but not all of the desired properties, and use this as the backbone of your breeding program

This requires a good knowledge of hosta species and cultivars, not only of their characteristics, but also of their pedigree.  How do certain treads inherit?
Hybridizing this way means you can control the results to a certain extend, although it's impossible to predict exactly what the results will look like.

You'll need to do a bit of planning:  hybridizing gives you the advantage of being able to cross plants that don't flower at the same time.  You'll have to harvest and store pollen of the pollen parents you want to use.  If you want to make a cross of an early flowering pod parent and a late blooming pollen parent, you'll have to harvest pollen in the autumn to use the next spring. 

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Collecting the required parent plants

If you don't own all of the parent plants you'll need for your hybridizing program, you have to acquire the missing ones.  Especially when you aim at the top in streaked pod parents, this can get a very expensive affair.

Another aspect to bare in mind is that you need plants that are large or old enough to flower and set seed.

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Comparing flowering periods

With parent plants that have overlapping flowering periods, your planning will be a lot easier.  On the other hand, some of the most surprising and innovative results in hosta cultivars can be achieved by breeding with parents that have a different flowering period.  In the latter, you'll need to store the necessary pollen.

A different approach (idea from Jan van den Top, renowned Dutch nursery man): put the early flowering parent in cold storage (a freezer) and let it flower simultaneously with the later flowering parent.

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Seed raising

The process of seed raising is identical for seeds from a hybridizing scheme and OP seeds.

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Selection

When and how will you make your first selections ?

Often, the real problem here is lack of time and space.  The more seedlings you grow on to maturity, the more valuable space they will take up and they more time they require.  Imagine 10.000 seedlings a year you have to nurse until maturity.
The vast majority of your seedlings won't be worth keeping anyway; you'll have to select the best, the prettiest. 
When you're breeding for multicolored plants, it's real easy a first: everything solid must go.
With solid colored plants you will inevitably have to grow on more plants for evaluation, since rather often it's only possible to judge the final appearance in mature plants (about 6 years old).

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Administration

A good administration is crucial to a good hybridizing scheme.  Depending on the number of seedlings that remain after the first selections, after about six years you'll have to be able to tell the parentage of a few dozen up to several hundreds of plants.
The ideal system is a simple one that doesn't require a lot of work, but still is very clear and gives you the least chance on errors.

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Experience

Experience is an absolute plus.  Much of the knowledge mentioned earlier on, isn't available in writing, so it can only be acquired by learning it yourself.

This learning process is bound to be one of trial and error.  You will make mistakes.  Only when you learn from them will you make progress.
Don't hesitate to experiment, trying to do things different from others.  If everyone keeps doing things the same way forever, the results will always be and stay similar.

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