What’s more beautiful than a handful of dinnerplate dahlia blooms? A dried-up fistful of dahlia seedheads of course! It might seem backwards to love a bouquet of brown pods more than a compote of 'Café Au Lait' flowers but let me explain myself. Within each dahlia seedhead lies up to 100 unique dahlia varieties just waiting to be discovered. The anticipation of being the first person to see a bloom that previously never existed far outweighs growing this year's Instagram star.
Dahlia seeds are each genetically different from their parents and seed-mates. This is because a dahlia has many ovules and requires each one to be fertilized by an individual pollen grain. Essentially, dahlias grown from seed will not be clones of the parent plant and each seed within a head will produce a unique bloom.
However, dahlias grown from seed will still grow to their full height, flower with abundance, and produce tubers. These tubers can then be saved and stored to produce a clone of the parent plant if desired. Dahlia hybridizers refer to these plants as “second-year seedlings.” Often, a hybridizer will grow a new dahlia variety for 3-7 years before naming the cultivar and introducing it to the market.
In order to collect viable dahlia seeds the plant must be given enough time to produce mature seed. Therefore, it’s important to stop deadheading the plants approximately 6-8 weeks before the first frost so the seed pods can mature. Once a dahlia flower fades and the petals drop, the seedhead will become pointed and slowly change color. It will transition from green to yellow before eventually turning brown. Dahlias with dark foliage will produce dark brown seedpods. As the seedhead matures, it should gradually dry out. If moisture drips out of the tip of a seedpod when squeezed it's still too young to harvest.
When a dahlia seedhead is ready for harvest, it will be brown and papery. I prefer to leave seedheads on the plant until they are completely brown. However, if the first frost looms you may be able to pick them sooner. To check if the seed is mature peel back the bracts on the outside of the seedhead. If the seed inside is green, it's not ready for harvest. If the seed is elongated and dark grey, brown, or black it is ready for harvest. When in doubt, wait for the entire seedhead to turn brown.
Once your seedheads are mature, cut them off the plant leaving a short stem. Take the heads inside and place them on a paper plate or towel to dry for 24 hours. Write the name of the seed parent on the plate and note the year the seed was collected. If you allowed the bees to pollinate the dahlias rather than isolate and hand pollinate, you can include the words “open pollinated” in your documentation. This means that you know the seed parent, but not the pollen parent.
Once the seedhead is dry, separate the seeds from the chaff by rubbing the head between your fingers. The hard seeds are dark grey or black. The papery chaff is a medium brown. Discard the chaff and place the seeds into small paper envelopes or seed packets.
Continue to document the seed parent and date collected on the envelopes. Store your seed packets in a dry place until it's time to sow them in late spring. There's nothing worse than opening a packet of saved seed and finding mold. Take extra care to ensure that the seed is completely dry, the envelope is dry, and the storage location is dry.
After you’ve fallen in love with growing dahlias from saved seed you may want to create your own varieties. This will require isolation, hand pollination, petal removal, and patience. First, isolate the seed and pollen parent that you would like to cross. Cover both bloom heads with organza bags when they're in tight bud and allow them to open in the bags. Take care to ensure the bag is tight around the stem so bees cannot visit the blooms.
When the blooms are mature and ready to be pollinated, they will show their disc center. At this time, remove the petals so they don't rot inside the organza bags. A clean, dry environment inside the bag is crucial.
Once the dahlias have mature pollen, remove the organza bag and collect the pollen from one flower with a small paintbrush. This dahlia is the pollen parent. Take the pollen to the seed parent and transfer it from the brush to the open stigmas of the seed parent (an open stigma looks like a short Y). Hand pollination should always occur on a dry day when bees are active.
Immediately re-cover the pollinated blooms with the organza bags so bees cannot reach them. Label the plants by noting the seed and pollen parents.Repeat this process for 3-4 consecutive days. In about 6 weeks the seedhead will be ready for harvest. If you notice excess moisture on the head during this 6-week period remove the bag and squeeze out the liquid before re-securing the bag.
2 окт 2024
