Basic Process of Cross Pollination

Year 1: Cross plant A with B or vice versa, then harvest the seed.

Year 2: Grow out the results of the cross (referred to as the F1 generation) in an isolated area and harvest seed from these plants.

Year 3: Grow out the harvested seed. This next generation (referred to as the F2) is where you should find the results of your aim. Select plants that have the desired trait (using our above example these would be plants that are dwarf and have yellow flowers). Once selected the plants can be self-pollinated (pollinating the same flower or using a flower of the same plant), or crossed with a plant with very similar characteristics, if they are self-incompatible (see explanation previously given under 'Once plants are isolated').

Subsequent years: Use the selection method to get seed true to type, remembering to sow out seeds of individual selections separately to increase your chances of attaining seed true to type quicker.

Special Notes

Fig 1. Prepare the bud for pollination by removing the petals

Fig 2. Remove the anthers from the flower

Fig 3. The flower is now ready for pollination

Fig 4. Pollinate your flower with pollen from the other flower

Sometimes you may have a problem with your desired plant trait coming through into the offspring. Under such circumstances you may need to back-cross some of the crossed plant selections with the original parent (either A or B, whichever has the characteristic that you are having problems with). The term back-cross simply refers to the method by which seedlings or offspring are cross-pollinated back onto one of the parents involved in the original cross.

It is very important to label your plants accurately, and to also keep a small sample of seed from every stage of the breeding, in case you encounter a failure and need to retrace your breeding steps.

How to Pollinate

Grow a bed of each of the two plant types to be crossed (in our example A and B). On the plant you intend to pollinate, any buds or flowers that have colour in them but have not yet opened should be used. Open the buds (fig.1) and remove the anthers containing pollen (fig.2 & 3). Dust pollen from the plant to be used as the pollinator onto the stigma of the one to be pollinated (fig.4). Plants can be pollinated either using a paintbrush or in some cases by rubbing the two flowers together. You can sometimes tell when the stigma is at its most receptive by the presence of a sticky or shiny solution appearing on the tip. In some plant types the stigma can also swell or change shape when receptive.

As you pollinate each flower, cover it with a bag or place an insect proof cage over the whole plant (see 'How to Isolate' above). Once successful fertilisation has occurred, plants have various trigger mechanisms which indicate success. Some will drop petals, on others the stigma will blacken and shrivel. After a period of time the ovule where the seed forms will begin to swell and ripen. Continue with more pollinations on other flowers as they open and label each cross with a lightweight label marked with non-fading ink.

Members of the Compositae (Daisy) family, e.g. Rudbeckia, Chrysanthemum, Tagetes and Dahlia have flowers made up of many tiny florets that open from the outer edge in towards the centre. These small florets should to be pollinated on consecutive days as they open inwards.

When to Pollinate

Mid morning is usually a good time to pollinate flowers. There is no dew on them and temperatures are adequate for the pollen to be effective. Avoid pollinating on a wet day, as any water on the pollen will kill it.

Special Notes

Healthy (not overfed) plants are essential for good seed production. Be ruthless when selecting and discard all but the best. This will save a lot of time and effort in the long run.

With either selection or cross-pollination you should send the seed to T&M only when a reasonable number of plants are fairly similar for the desired trait. Enclose a colour photograph if possible.

Knowledge of your plants will prove invaluable in your breeding work. Try to find out as much as possible about the genus or species you are working on before you start. This is also a good way to check that there are no similar plants already in cultivation before you submit your entry. Make notes on breeding and at various stages of the plants growth and development. It may be helpful to search the Internet and to contact organisations like the Royal Horticultural Society, to find out about groups interested in the same plants as you.