Last updated on March 27th, 2023 at 07:42 pm
By planting dahlia seeds, you can grow your own one of a kind dahlia plants. Each individual dahlia seed holds the genetic material of a unique plant. Learn how to plant dahlia seeds, and grow a beautiful home grown dahlia patch.
If you enjoy hybridizing, harvesting and planting dahlia seeds can be lots of fun.
It’s not quite as easy to hybridize dahlias as it is to hybridize daylilies, for example, however it can be done.
What I generally do is allow the bees to spread the pollen, and then collect the dahlia seeds when they are mature at the end of the season.
With strategic placement of compatible dahlia flowers, you are almost guaranteed some crossing of your intended blooms.
Then all you have to do is harvest the dahlia seed pods, collect the dahlia flower seeds, and then plant them out the following spring.
How To Plant Dahlia Seeds
It’s a good idea to get your dahlia seeds off to a great start by germinating them inside about four to six weeks before your last frost. This will give them a head start on the growing season, and a better chance for successful blooming the first season.
I was very excited to pull out all the dahlia seeds that I had saved last season. Many were from the large decorative types which I had planted closely together.
The initial planting process of dahlia seeds is very simple and easy.
So let’s have a look at how to plant the seeds.
Should I Soak Dahlia Seeds Before Planting?
There is no need at all to soak dahlia seeds before planting.
Once planted they will be watered in, and the moist soil and heat will help to stimulate the germination of the seeds.
The seeds will germinate very quickly after planting without any soaking.
Methods Of Planting
I like to give dahlia seeds the best chance for success when starting out, by providing them with the best place in which to germinate.
This generally means starting the seeds in a good sterile seed starting mix that is free of weed seeds.
As well, it involves keeping the seeds moist and warm during the germination process.
The easiest way to provide these elements is to plant the seeds indoors in pots, especially in colder growing zones like our zone 5b.
That said, dahlia seeds can also be grown directly in the garden as well, when conditions are right. If you choose to plant outside, make sure to plant into a prepared bed and keep the soil moist until the plants start to grow.
So let’s have a look at both methods of planting dahlia seeds.
Planting Indoors In Pots
Planting indoors in pots is a choice location for planting dahlia seeds for a number of reasons. You will likely have more success with your seeds in this location due to the consistent temperature and watering schedule.
When growing indoors there is often more control over the many environmental factors which are important for successful germination.
It is always a bit of an effort to maintain a moist soil until germination is complete, especially if growing outside. Keeping the soil moist is important, because if the soil becomes dry this can damage the germinating seed at a vulnerable time.
It can be beneficial to start dahlia seeds early and inside, especially in colder regions. It gives the new plants a head start on the season. They have a better chance to flower in the first year if they are given lots of growing time.
You are also able to plant out larger and sturdier young plants when you start them early indoors, which gives them a fighting chance in the garden.
Planting Dahlia Seeds Indoors:
- Planting dahlia seeds indoors is very easy.
- Try to use a fairly deep and wide seed tray to support the dahlia roots, rather than starting out in smaller planting trays, such as a 125 cell tray for example.
- 75 cell trays provide more space, along with smaller pots or cups which can also be planted with individual seeds. I also like to use deep cups, such as solo cups which give lots of space for the roots to grow.
- Fill the containers with a good seed starting medium.
- Make a small hole in the centre of the soil about 1/4 inch deep, and bury the dahlia seed. Cover the seeds with soil.
- Water in, and provide bottom heat.
- Keep the soil moist until germination, which should occur within two to ten days.
- Once sprouted, remove from the heat mat and place under grow lights. The seedlings should receive at least 14 hours of light for optimal growth.
- Bottom water the trays as needed.
- Grow under grow lights until the seedlings are ready to be planted outdoors, once the danger of frost has passed.
- It’s very important not to expose the new dahlia seedlings to any frost, as the plants are very frost tender. Dahlias can be easily injured by frost.
- Be aware of the last spring frost date to know when it is safe to plant out in your area.
- Make sure to harden off the seedlings gradually, before planting out, allowing them to gradually acclimatize to the outdoor environment.
- Plant out into a sunny spot in the garden once the small plants are hardened off.
Planting Outdoors In Pots Or Directly Into The Garden
You can also plant dahlia seeds outside once the weather warms up.
If you are planting dahlia seeds outside in cooler climates, you may not have the growing time available in your climate to have the dahlias flower within the first year.
But that’s okay, as you will likely get flowers the second year from tubers which you will harvest at the end of the season.
Can You Plant Dahlia Seeds Straight Into The Ground?
- Yes you can plant your dahlia seeds into the ground in spring, as long as your planting time is after your last frost date.
- If you are planting your dahlia seeds directly out into the garden, make sure to do this after the risk of all frost has passed due to the tender nature of dahlia seedlings and dahlias in general.
- The seeds will grow best if planted after the soil surface has warmed up. If planted earlier they are at risk for moulding.
- Sow into a freshly prepared garden bed that is full of a good humus soil.
- Plant the seeds approximately 1/4 inch deep, and cover with soil.
- Space approximately six inches apart.
- Water the soil, and keep moist until germination, which should occur within two to ten days, as long as the soil is warm and remains moist.
- Too much moisture can cause rot, so allow the soil to drain well between waterings.
- Remember to label the rows with the parent plant name if you are planning to keep track of the parentage of your seeds. Just place a stake in the garden at the head of the row, with the parent plant written in a permanent ink.
Planting Dahlia Seeds Outside In Pots
- Planting dahlia seeds outside in pots is pretty easy.
- Sow seeds at least six inches apart in large pots, in a good soil mix, and bury 1/4 inch deep.
- Water in well, and keep the soil moist until germinated.
- Consider staking for plant support, especially for taller varieties.
How Long Do Dahlias Take To Grow From Seed?
After you plant the dahlia seeds, they will usually germinate within two to ten days.
You will know when they have successfully germinated when you see the tiny green leaves emerge from the soil.
It takes dahlias a bit longer to grow from seed to bloom, than it does for a dahlia to grow from a tuber.
Dahlias will need at least 120 days to grow from seed to bloom, in the proper conditions.
If you are hoping to see dahlia blooms from your seeds in the first year, consider starting them inside early to get a head start on their growth.
What Will Dahlias Grown From Seed Look Like?
The exciting part of growing dahlias from seed is that you just never know what they will look like, until they actually bloom.
Dahlias come in many sizes and shapes, and in a wide range of colours. There are so many dahlia varieties.
Most often dahlia seedlings will present with the dominant traits of the species, which may not be exactly what you are looking for in a garden plant.
You may be surprised to find that many of the seedlings have single blooms and smaller flowers.
This is because the most dominant characteristics in the plant are blooms with single flowers or a single set of petals, open form, tall stems, and small and downward facing blooms.
These are dominant traits in dahlias, and therefore your dahlia seedlings will demonstrate many of them. This will be true especially if you have grown from your own seed, and have dahlias with any of these characteristics already growing in your garden.
I highly recommend the book Dahlia Breeding For The Farmer-Florist And The Home Gardener by Kristine Albrecht, which goes into great detail about hybridizing dahlias, and the resulting dahlia seedlings.
Do Dahlias From Seed Produce Tubers?
When you grow dahlias from seed, they will begin to form tuberous roots.
At the end of the growing season, the tubers can then be dug and safely stored away for the winter until the dahlia tubers can be planted out again the next spring.
The tubers from new dahlia seedlings are usually smaller than those formed from mature plants grown from tubers themselves.
Dahlia Seedling Care
So you have planted and germinated your dahlia seedlings. Now it is time to look at dahlia seedling care, including light requirements, moisture requirements, pinching and lifting at the end of the season.
- Dahlias grow best in fertile and well drained soil.
- When transplanting from the seedling pots into the garden, make sure that they are planted into rich amended soil with good drainage for the best growth results.
- You can grow your dahlia seedlings fairly close together if you have limited space. Plant approximately six to eight inches apart.
- Dahlias do best in full sun, as long as it is not scorching heat.
- Dahlias require at least six hours of direct sunlight per day for optimal growth. Any less than that may result in leggy plants with weaker stems.
- As well, to get flowers during the first season, it is important to plant the seedlings in full sun.
- Dahlias require moderate moisture.
- Do not overwater, as this can lead to rotting of the dahlia tubers.
- Mulching around the plants will help to hold the moisture in the soil without the need for extra watering.
Pinching Dahlia Seedlings
- You can pinch dahlia seedlings, just as you would any other fresh growing Dahlia plant.
- Pinch out the growing tip when the plant is about eight to ten inches high.
- Pinching encourages side shoots and more flower growth. It also promotes strong stem growth and more bushy plants.
Staking The Seedlings
- Staking is part of dahlia care and maintenance, and staking the dahlia seedlings can be a good idea.
- Dahlia plants can grow quite tall and become very heavy when covered with large blooms.
- Sometimes the large plants can even fall over or tip sideways in strong winds if not supported.
- The seedlings may not get large enough in the first season, but just be aware that staking is an option.
- To support the seedlings, you can stake them individually using a plant stake.
- Alternatively you can corral the plants together, by placing posts on the outside of the dahlia rows or garden beds. Tie the posts together with several layers of twine, one above the other, about a foot apart.
- This creates a fence of sorts, which can help to hold up the plants in case they tip over.
Culling The Seedlings
- If you are growing your dahlia seedlings to choose the best from the batch, you will likely need to cull the plants that are not of good quality, or those that you don’t intend to keep.
- You will be able to select the best dahlias to keep once they have bloomed.
- Make sure to label the ones that you plan to keep, and dig them up at the end of the season. The others can be left to compost in the ground, or dug to share with others.
- Culling can be a difficult process for many, however it only makes sense to keep your best plants for storage.
End Of Season Care
- If you are gardening in zones 6 and below, you will need to dig your dahlia tubers up out of the ground at the end of the season.
- This will include the tubers formed from your brand new seedlings.
- Dig the tubers after the first fall frost which has caused the leaves to blacken. A light frost does not count.
- To perpetuate the plants, safely store them away for the season, and before you know it you will have lots of tubers from each of your new plants.
Dahlias are wonderful garden plants and make excellent cut flowers.
Planting dahlia seeds is a great way to start brand new dahlia plants for the flower garden, and is becoming a popular hobby of many flower farmers.
Growing dahlias from seed is also a great way to fill your garden with beautiful flowers.
Each seed contains the unique genetic material of a brand new hybrid dahlia, so you never know what you are going too get until the flower actually blooms.
Planting dahlia seeds is easy, as the seeds are easily germinated if grown using the right techniques.
For best results, start the seeds early indoors.
Make sure not to plant out the seedlings until the risk of frost has passed, as dahlias are very frost tender plants.
If you start the seeds early enough, you may get blooms within the first season. If not, they will bloom the following season from the tubers that are produced.
You can buy prepackaged dahlia seeds, but it’s also fun to collect your own at the end of the season. Save the seeds from your favourite cultivars, and see what beautiful dahlia blooms that you can grow.
This year I have lots of seed to plant from Cafe Au Lait, and Kristine Albrecht’s KA’s Cloud. I look forward with great anticipation to see the news seedlings that will develop and grow.
Have you ever tried to save and plant dahlia seeds? Be sure to leave a comment below to share your experience!