Methods

Movie version (48MB)

Text only version

Cross pollination is the process of applying pollen from one flower to the pistils of another flower. Pollination occurs in nature with the help of insects and wind. This process can also be done by hand to produce offspring with desired traits, such as color, size or pest resistance. To cross pollinate you will need to prepare two different roses that are at a similar stage of development. For example a red rose bud and a white rose bud.

1. Choose a rose bud with outer petals that are just begining to open and inner petals that are still wrapped around one another.

2. Remove all the petals by plucking or cutting off with scissors.

3. Once the petals are removed you can see many stamen. One stamen is composed of a long thin filament topped with a circular structure, called an anther. The anther contains the pollen. Removed all the stamen and place them in a container. Lable this container with the flower variety and the date.

The stamen can be plucked of with tweezers or cut off with scissors. Make sure you remove all the stamen from the flower, carefully check the among the pistils and along the outer edges of the base of the flower.

4. Place a bag over the flower and secure it at the bottom with a twist tie so that no insects can crawl in. You want to make sure that you are the only one to add pollen to the pistils.

A paper bag will do if you don't have any bags made specifically for this purpose. Lable the bag with the flower variety and the date.

5. Store the anthers in a warm, dry spot. The anthers should ripen by day three, check them each day for the presence of a green to orange dust (depending on the variety). When you see the dust collect in the container you can apply the pollen to the pistils.

6. Repeat steps 1-5 on the second rose to be cross pollinated.

The pistils are located in very center of the flower. On a rose this structure is shaped like a gourd with a thin elongated neck, topped with a knob called the stigma. Pollen enters the top of the pistil through the stigma, travels down the style to the ova which are contained in the ovary at the base of the pistil. If the ova are fertilized they develop into seeds.

This asiatic lily clearly show the three parts of the pistil. The very top is called the stigma, the middle is the style, this connects the stigma to the ovary at the bottom of the pistil.

7. The pollen is applied to the pistil by simply dipping a cotton swab or your finger into the pollen and then carefully wipeing it along the top of the pistils.

The idea is to get pollen on every pistil. If you are going to be pollinating more than one type of rose, use a different swab for each flower or wash your hands in between types to prevent pollinating with the wrong pollen. Repeat this process for one to three days to make sure that both pollen and stigma are ripe and receptive.

8. Each time pollen is applied place the bag back over the flower and secure it.

9. Let the seeds ripen in the rose hip. If the ova are not fertilized the rose hip will turn brown and shrivel. If fertilzation was successful the rose hips will swell as the seeds develop. It will take two to three months for the seeds to fully develop. After this time the hip will turn brown and should be harvested.

10. To harvest the hip, it is cut from the bush, then cut down the middle with a sharp knife. There may be one to many seeds depending on the number of pistils that were successfully fertilized. Remove the seeds and place them in water, save only the ones that sink. The sinkers are placed in a plastic bag with peatmoss and refrigerated for eight to twelve weeks. Make sure that you lable the bags with the parental cross.

Alternative treatment to lengthy stratification process outline above is to soak the seeds in water for 2 days, then plant. I will try both procedures.

11. After the seeds have been chilled (or soaked), they are ready to plant. Plant the seeds a half an inch or so deep in loose sterile planting media, with good drainage. Keep the seeds moist and between 65 to 70 F. Make sure that you label the container with the seed's parentage.

12. The seeds will germinate in six to eight weeks, although some may take much longer. Keep seeds moist and warm to encourage germination. If you had placed several seeds per pot, transplant seedlings to seperate pots when they sprout a second set of leaves. Plants will grow from 1-3 ft in the first season.