Growing Dahlias From Seed: What Actually Happens

A dahlia tuber gives you the same flower every year. A dahlia seed does not. Every seed in a packet grows into a plant that has never existed before, and will never exist again unless you keep its tuber.

That is the whole appeal, and it is also why people find their first packet confusing. You plant ten seeds from one variety and get ten different flowers.

Where the seed comes from

Most seed people grow was not hand pollinated. Growers with hundreds of cultivars often collect open pollinated seed from the patch and sell it, so what you know is where the seed came from rather than which plant supplied the pollen. The bees handled that part.

I grow seedlings from Floret seed. Floret is a large seed farm here in Washington, and their Petite Floret seed is collected from their own patch. So the seed parent is Petite Floret and the pollen parent is whatever the bees were carrying that day. Three of my seedlings came from that one packet and none of them look alike.

What a first season looks like

Seeds start indoors a few weeks before your last frost, go out when the soil warms, and most bloom the first year. That is the surprise for people used to perennials: you sow in spring and see flowers the same season.

Some will be lovely. Most will be ordinary. A few will be single or muddy or flop over, and that is normal, not a sign you did anything wrong. Breeders grow hundreds of seedlings to keep a handful.

Deciding what to keep

At the end of the season you dig the tubers of the ones you want again and let the rest go. The judgment is not only about the flower. A beautiful bloom on a plant that makes no storable tuber is a plant you cannot keep, and stem strength matters as much as color if you ever want to cut it.

The hard part is remembering. By the following spring you will not recall which of your seedlings held its face up, which one bloomed first, or which one came from which packet. Photographs taken at the time are worth more than any note written in November.

Keeping the record

This is what our hybridizing tools are for. Each seedling gets its own record: the seed parent, the pollen parent or open pollination, the year you first grew it, photographs as it blooms, and a keep, watch, or cull decision each season. Seedlings from one packet group together, so you can see everything that came from a single origin side by side.

Your first twenty seedlings are free, and they stay private to you. They never join the Library or your public garden unless you decide to share them.

If you are growing out a packet this year, start a record for each seedling while they are still in front of you.