Dahlia Hybridization: Evaluating Plant Vigor and Plant Habit

Are you growing dahlias from seed this year? Do you need help deciding which blooms to keep? We can help! Today we’re continuing a helpful series sharing how we decide which first-year dahlia seedlings make the cut here at Triple Wren Farms! Each year, we consider these four things:

Blooms
Plant Vigor
Plant Habit
Tubers

We covered blooms in a previous post and today we’d like to talk about plant vigor and habit.

You’ve planted your dahlia seeds. You’ve lovingly nurtured them into full grown plants and you have your first blooms. You have fallen in love with a few of your new blooms. But… are they tough enough to weather the season’s demands? Are they floriferous enough to earn a spot in your garden? Before we decide to keep a seedling for future years, we consider plant vigor and habit. Let’s start with plant vigor.

Plant Vigor

What does plant vigor mean? The word vigor means “physical strength or good health.” It’s obvious if a plant is diseased or unhealthy. Clearly, you wouldn’t keep those new seedlings. But beyond this, there are 3 specific characteristics of plant vigor (besides the overall health of the plant) that we consider as we’re observing new seedlings throughout the season.

We consider:

– Bloom Productivity

– How fast the plant recovers after harvest

– Stem strength throughout season

Bloom Productivity

This is exactly what it sounds like–how many blooms does this plant make throughout the season? Keep in mind that this will vary based on dahlia form, (i.e. dinnerplate dahlia plants make fewer blooms than ball form dahlias). But in general, keep track throughout the season so that you know about how many blooms your seedling makes. Record whether or not you pinch it, and whether or not you cut flowers from it or simply let it grow untouched. It’s also helpful to keep track of the number of days it takes to bloom. It’s not a deal-breaker if a seedling blooms later in the season, but it’s helpful to know how late in the season.

How fast does the plant recover after harvest?

Making a bouquet from flowers grown in your own garden is one of life’s little delights. If your new dahlia is going to perform as an amazing hybrid variety, it needs to be able to handle its blooms being harvested with grace. You should observe not only how the blooms last in the vase, but also how the plant does. How long does it take to get new branching and green growth from the places where you’ve harvested flowers? Cut blooms from your dahlias, and then observe and record what your plant does over the next few days and weeks. (Remember to cut deeply for best dahlia health.)

Stem Strength Throughout the Season

Another characteristic to consider is stem strength. How strong and how long are the stems? Can they hold the weight of the bloom? Are the stems rubbery or very weak? Take notes about this characteristic throughout each trial season. A good “keeper” dahlia will have strong stems. At Triple Wren Farms, we specialize in growing dahlias for cut flowers, so we’re looking for both long and strong stems.

Now, let’s move on to plant habit.

Plant Habit

If you are new to hybridizing dahlias, you may be wondering what plant habit means. You know personally what a good or bad habit is and what a habitat is, but what on earth is a plant habit?! It simply means the form or shape a plant takes. We’re going to talk specifically about the height of the plant and the branching habit of the plant.

Height

Since we’re focused on growing dahlias for cut flower gardens, we only want to keep dahlias with long stems. We’re looking for plants that are a minimum of 30 inches tall. You’ll want to keep good records about the height of your seedlings as they mature. We keep plants that are anywhere from 30 inches tall up to 6 feet tall!

Branching Habit

This is closely tied to how fast the plant recovers after harvest. We want the dahlia plant to make new branches quickly after cutting and we want them to make lots of new branches so there are lots of flowers to harvest.

Take Notes!

There are so many characteristics to keep track of when hybridizing a new dahlia variety! Taking copious notes and pictures throughout the season will help you to remember everything that you have observed. It will all be worth it when you have a new variety of dahlia that you have nurtured through a few seasons and are ready to release into the world.

Next time, we’ll talk about tubers. Feel free to ask any questions you have in the comments below!

Want to learn more about growing dahlias? The Garden is a positive online membership community offered by Triple Wren. Membership includes:

First access to TWF tuber and seed sales
A wealth of flower garden How-To topics
Frequent seasonal Live Trainings and Q&A’s
Our “Anyone Can Grow Dahlias” e-course
Personalized gardening advice
Encouraging gardening community and more…

Visit our website to find details and join The Garden!