Breeding Dahlias for Beginners
by Ted J. Kennedy
Growing new dahlias from seeds is fun. I am going to cover this subject in two parts:
(1) How to collect seeds and plant seeds.
(2) How to increase your odds of getting a really nice dahlia.
How to collect seeds and plant seeds
Gathering dahlia seeds is very easy. Many varieties make lots of seeds. There is a ripening process for dahlia seeds
and when the seed pods reach the "straw green" stage, they can be harvested. Stages in seed ripening: The flower
blooms and eventually the pollen center shows and the bees start to gather pollen. Then the petals fall off of the flower
(you should make sure all petals fall off) and the seed pod forms. At first the pod is very green and soft. During the next
two to three weeks the seeds inside the pod are ripening. When the seeds are ripe the pod will turn to a "straw green"
or even a light tan color. The seeds inside will change color too and will go from white or green to a very light gray to a
darker gray and sometimes to black. At this point you can harvest the seed pods. We pick them like we pick cut flowers;
that is with a 6 inch stem. We label the bunches of seeds although some people mix all the seeds together. Some
people like to remove the seeds from the pods right away. Others let them ripen further indoors. We store our seeds in
small envelopes labeled with the seed parent and the date of harvest and how many seeds are in the envelope. Be sure
they are completely dry before you store them. We then store them in shoe boxes in our basement in a dry cupboard.
In the Spring, on about April 1st, we germinate the seeds in small 2.5" pots filled with a very fine soiless mix called
germination mix. We place about 15 seeds into the pot and place a label in the pot and cover the seeds with 1/4 inch of
the mix and water each pot. We put the pots in area that is room temperature or slightly above 72 degrees. They usually
sprout in 5-7 days and we let them grow under indoor lights for a another week or so before we carefully divide the
seedlings into their own pots. It should be noted that many perfectly good looking seeds may not sprout and this
probably due to genetic incompatibility between the parents. We grow the seedlings in our small heated green house
and plant them into the ground on about May15th. At this time they are about 6-8 inches tall. The seedling bed has
double rows and the plants are about 6-7 inches apart. They start blooming in early July.
How to increase your odds of getting a really nice dahlia.
Dahlias are octaploid meaning that they have 4 times as many chromosomes as most organisms. This means that you
cannot use classical breeding techniques where one depends upon isolating recessive and dominant traits and then
using them to improve your plants. Dahlias do not have recessive genes in the same way that diploid organisms do.
There are too many genes and to make a long story short, the best way to breed dahlias is to breed like to like. Genes
for a specific traits are quite often displayed in the plant as levels of influence. For example there are genes in dahlias
for bigger plants and flowers. The more genes for “big’‘you have, the bigger the plant. So in some ways breeding
dahlias is easier. The golden rule for breeding dahlias is to breed like types to like types to get like types. If you want a
nice pom dahlia you need to cross some poms. If you want a giant sized dahlia you need to cross large dahlias and
hope to get some big ones. Having said that there are lots of crosses that produce the unexpected. Enough said.
Now we need to explain how we can get like types of dahlias to cross with like types of dahlias.
There are several ways to do this. The most time consuming and probably the most effective way is to hand pollinate the
flowers and to make sure that you have done the pollination and not a stray insect. That method was covered in the
video by Wayne Shantz. (You should watch this video)The other methods are:
(1) Isolation: Growing only flowers that you want to be pollinated together in an isolated area so that the bees can only
cross the varieties you have selected. They need to be isolated by at least 50 feet and more is better.
(2) Removing Flowers and adding extra pollen. Remove flowers from plants that you do not want to pollinate your
mother plants. Conversely, you can add extra bouquets of pollen rich flowers near the flowers you want pollinated. A
bouquet in a vase tied to a stake will suffice. Also, you can attempt to add some pollen to the ripening flowers just in
case the bees are too lazy. Another arcane method is to use a bee tunnel. Plants to be pollinated together are planted
in a row. The row is covered with a fabric to form a tunnel. The bees are forced to fly into the tunnel and will continue in
the tunnel pollinating as they go until they come out at the other end. I have never tried this method.
(3) Grow only specific types of dahlias in your garden Many casual breeders just grow fully double flowers in their
garden. Others just grow open centered types. If you grow open centered flowers, nearly all of your fully double flowers
will be pollinated by the open centered types and your percentage of fully double seedlings will be very low.
Do dahlia seedlings make tubers? Yes, they do but they are usually fewer and smaller the first year.
Do Dahlia seedlings change in the second year? Most of the time they do not but there are some exceptions. The
first exception is health and some dahlias pick up viruses and disease right away. The other “change” is actually in your
mind. People generally remember the seedling as being better than it actually was. They were so excited in seeing their
baby blooming that they tend to ignore it’s faults. Also, the weather plays a big part as most seedlings are blooming in
the late part of the season when it is cooler and they may not do well in hot weather. Also, some dahlias change for the
better the second year. That may be because they were grown in crowded, less than desirable conditions in the first
How many seedlings does it take to get a good one? Open Pollinated: Most breeders report that they average
one really good one per 1,000 seedlings. Of the 1,000 seedlings about 100 will be attractive and if you have the time
and space can be kept for further evaluation. Hand pollinated: We believe that if you hand pollinate that you increase
the odds of getting a nice one by at least two times. How much you increase the odds depends on your ability to cross
the right dahlias. Results from the best isolation methods are as good as hand pollinating as has been proven by
several successful breeders.
|Seed Pod after all ray
florets have fallen off