Saturday, July 24, 2010

How to Make a Brand New Rose

A new rose from 'Gemini' X 'Sunset Celebration'
So, “how do you make new roses?”, you may ask.  New roses are made by cross-pollination.  You hybridize one rose with another by taking pollen from the one rose and applying it to the stigma of the other rose.  The seeds develop in the rose hip that forms after the pollination is accomplished.  For those who are new to this hobby, the rose hip (the fruit of the rose) is the rounded swelling that forms where the bloom used to be, kind of like an apple or peach that forms where the blooms were.

Wherever you live, springtime is the best time to hybridize roses, and where I live, in Bakersfield, California, the best months are in April and May. Hybridizing must be done sufficiently early to allow time (3 1/2 to 4 months) for the developing rose seeds within the hip to mature before the weather turns cold.

In order to maximize success it is important to select reliable parents for your rose hybridizing project. If you have a particular rose or two that produces lots of hips, try them for use as the seed parents (the hip bearing parent). Among the larger flowered roses, good seed parents to try are: ‘Gemini’, ‘Stainless Steel’, ‘Singin’ in the Rain’, ‘Fabulous’, ‘Queen Elizabeth’, ‘Sheer Bliss’, ‘Lynn Anderson’ and ‘Livin’ Easy’.  For the minis, try  ‘Rise 'n' Shine’, ‘Fairhope’, ‘Halo Today’, ‘Black Jade’, or ‘Pearl Sanford’.   In my experience, all of these roses reliably produce hips with lots of seeds, and ultimately they all have high germination rates.

Most modern roses produce at least some pollen and can be used successfully as pollen parents. One strategy in selecting a pollen parent for a particular cross is to choose one that has some good qualities that may be lacking in the seed parent.

Before proceeding, a brief review of rose anatomy is in order. Roses are monoecious, meaning that both male (pollen) and female (seed) reproductive cells are present on flowers of the same plant. Pollen is produced in the anthers (yellow sacks at the tops of filaments surrounding the stigmas). The stigmas atop thread-like projections come out of the very center of the bloom. The stigmas produce a sticky substance to receive pollen, which after applied to the stigma, the pollen germinates and migrates down the threads to unite with the ovules to produce seeds. For more detailed information on rose anatomy please do a search on Google or any other internet search engine.

In order to prevent self-pollination of the selected seed parent, the anthers (pollen sacks) must be removed from the blooms before any of it’s own pollen is released. This is best accomplished at sunrise when blooms are in the 1/3 to 1/2 open stage (blooms that would normally open that day). First, all of the petals are removed. This procedure allows better access to the center of the flower. Next, with curved tweezers or small scissors, the anthers are removed. If the variety selected as a seed parent will also be used as a pollen parent with other roses, the anthers may be collected into a cup and placed uncovered in a dry place where they will release pollen by the next day.

Blooms that have been appropriately emasculated of their anthers are immediately ready to receive pollen from another variety. Pollen has the appearance of yellow or tan powder and may be applied with either a finger or paintbrush to the stigma of the seed parent. In order to remember what pollen parent was used for the pollination, a label (paper tags with a string attached, available at stationery stores work well) should be gently attached to the stem below the bloom, which has just been pollinated. Information written on the tag may include the cross and the date, but I just note the pollen parent (it’s easier that way).  Later, when the rose hips mature and are harvested, both parents should be written on the zip-lock bag used to store the hips in order to document the cross.  Proper notation for a cross always lists the seed parent first followed by the pollen parent. For example, in a cross where ‘Gemini’ is used as the seed parent and ‘Sunset Celebration’ is used as the pollen parent, the notation would be: ‘Gemini’ X ‘Sunset Celebration’ (or just GEM X SUN for short).

After hybridizing, it is not necessary to cover the pollinated blooms since bees and butterflies will usually ignore roses without any petals. For approximately the next 6-12 hours, care should be taken not to wash off the pollen from your crosses (by rain or overhead sprinkling). If the cross is successful, a rose hip will begin to form in 2-3 weeks. One should not expect more than about 30% of their crosses to be successful. To improve success, some rose hybridizers recommend that the rose bushes selected to be seed parents should not receive fertilizer or be watered excessively.  I used to think that too, but have found that most rose seed parents still do better with some fertilizer and normal watering.

Later on, assuming that some of your crosses are successful and you have plump rose hips forming, you can sit back and contemplate what characteristics your future rose seedlings may have, knowing that each will be one of a kind, and completely unique!


New 2010 rose seedlings growing in raised seedling benches.  Please note, roses can be grown in regular plastic pots and then later planted in the ground so that they can fully mature.

11 comments:

  1. Hi Jim.

    What fertilizer regime (ie. what type, and what frequency of dosing) do you use for all your roses planted in the ground (eg. seed parent roses)?

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  2. Hi George,
    Most of my seed parents are in 7 gallon pots. I use a good soluble 20-20-20 with minors for them, and fertilize about once or twice a month, probably about 1/4 to 1/2 gallon per plant. For plants in the ground, I use granular fertilizer in the Spring and Fall. Usually lawn fertilizer is cheapest. Soon, I will be using horse manure on the roses in the ground!

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  3. Yeah ok.. that is great information, Jim.

    I'll do similarly to my roses from now on.

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  4. Great information, Jim. Well done!

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  5. You have a very colorful rose seedling bed coming up their. So how big is that bed and how many seedlings would you estimate is in there?

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  6. Thanks Paul!

    Hi Wuchen, I have four raised seedling beds in the greenhouse. Each is 5 feet wide x 20 feet long. There are between 3,000 to 4,000 seedlings per bench to start with, but the culling begins quite early. At the stage in the photo, there were probably between 2,000 to 3,000 seedlings.

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  7. So what minor minerals do you want a fertilizer to have?

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  8. Hi again Jim.
    How deep are the seedling beds in the picture?

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  9. Hi Wuchen, I just use a good soluble fertilizer "with minors". To be honest, I don't remember which minors or the concentrations of them.

    Hi George, the seedling beds are about 8 inches deep at planting time, but over time and with watering, they usually settle to about 6 inches deep.

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  10. Again, thanks so much Jim for the helpful information. I am trying to replicate what you do on a tiny scale. I am sowing them @30-40 seeds per square foot, in one foot deep boxes.

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  11. How do you germinate rose seeds. My rose seeds are difficult to germinate. Should I allow it to germinate in Fridge or should I take out from fridge and sow in normal room temperature, say 25 C

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