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Flowerface Dahlia Growing Guide

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Dahlias are the queen of the late summer garden and are quite easy to grow

with a few steps!

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Overview
Dahlias are grown from tubers, enlarged starchy roots designed to store water and nutrients for the plant. Tubers sprout from eyes that are found around the base of the stem. Dahlias come in a wide range of colours and shapes and are generally 3 - 5 feet tall once fully grown.

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Anatomy of a dahlia tuber
Healthy and viable dahlia tubers consist of three main parts. It is important to have all of these parts intact to grow a healthy plant.

• Crown - This is the top of your tuber and where the stalk from last year was attached. This is the part where the eyes will sprout from. If you can’t locate the eyes don’t panic, some dahlias don’t readily show their eyes until they are starting to sprout. Alternatively, if your dahlia tuber is already sprouting and you break off a sprout, it will readily grow a new one.

• Neck - This is the most delicate part of your dahlia tuber. The neck attaches the tuber to the crown. If it is broken it will not be able to send energy from the tuber to the crown.

• Tuber – This is the storage unit for your dahlia plant, it's the largest part of your new tuber. The tuber holds nutrients and water that feeds your dahlia until it has formed a root system in the ground.

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Dahlia planting instructions
To plant dahlias you must first until your last frost has passed. Here in Victoria it is usually mid - late April. Once the danger of frost has passed, decide where you want to plant your dahlias. Dahlias can be planted in pots and containers, but they do best when planted in the garden. Dahlias need full sun and rich, well-draining soil to produce healthy plants with lots of flowers.​

 

• Dig a hole approximately 5 inches deep and put some compost and sprinkle of fertilizer (I like Gaia Green Organic All Purpose fertilizer) into the bottom of the hole.

• Place your dahlia tuber horizontally in the hole with the eyes facing upwards. The eyes can sometimes be tricky to spot, they are knobbly bumps that appear on the crown of the tuber. It’s ok if you can’t see the eyes, as long as you have all three parts it should sprout. Plants are resilient and the shoots will find their way to the surface of the soil. If your tuber has sprouts already and you accidentally break it off, fear not! It will grow a new sprout just fine.

• Cover your tuber and wait…

• Once you have planted your dahlia tuber do not water it too much until you see green sprouts emerging from the soil. The soil should be damp, not waterlogged or bone dry. This can sometimes take up to two weeks. If it rains before the sprouts emerge that’s ok, but I generally try to find a dry week to plant my dahlia tubers. Too much moisture in the soil can lead to your tubers rotting before they sprout.

• When deciding on dahlia spacing there are a few options. Cut flower production dahlias are generally planted 1 ft apart in rows. If your dahlias are in a more ornamental setting you can disperse them throughout your garden, but be sure to give them approximately 2 ft. on each side so they do not smother other plants. Giving your dahlia plants more room enables airflow and discourages diseases & insect issues.

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Staking
Dahlias need staking because the flowers are top-heavy and staking prevents the plants from toppling over under the weight of the flowers. There are a few different ways to stake dahlias but the easiest way is to insert a stake into the ground at the time of planting. To do this find a stake that is fairly sturdy and able to support the plant. You can use bamboo or metal stakes from your local garden center. Insert the stake firmly into the ground approximately 4 - 6 inches from the crown of your tuber before you cover it with soil. As your dahlia grows you will attach it to the stake to stabilize the plant. Make your first attachment once your plant has reached approximately 2 ft. and again at 3 to 4 ft. 

If you are growing a row in a straight line, you can use the corralling method for staking. For this method insert your stakes at the corners and at 5 ft. intervals along the line of dahlias, both on the front and back of your row. Once your dahlias have reached 2 feet tall, run a durable string between the stakes to create a cage around the dahlias. This will be repeated a second time higher up once the plants have grown taller. This corralling method is commonly used by cut-flower growers when we are growing rows of dahlias for production.

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Dahlia care
Once your dahlia tubers have sprouted above the surface you can begin regularly watering them. Dahlias need very little water until they have reached 6 inches tall. After this point they should be watered regularly to maintain moisture but avoid waterlogging the soil as dahlia tubers are prone to rot.
Once the plants have reached 6-10 inches I highly recommend pinching your dahlias. Pinching is a technique that forces your dahlia to branch from the bottom and creates more stems. To pinch simply snip the top third of the plant down to just above a strong leaf set. This is a technique used by cut flower growers as it yields more blooms per plant. Pinching your dahlia plant gives you a sturdier bushier plant with lots of blooms. If you choose not to pinch your plant, you will get a large single-stemmed plant with one large bloom at a time.

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Harvesting dahlias
Now that your dahlia is happily growing and blooming you can harvest some flowers to bring into your home. For the best cut, choose flowers that are almost fully open but not yet fully blown. They will continue to open in the vase. The petals at the back of the flower head should be firm and shouldn’t fall off when you handle the flower. With sharp snips, cut deep into the plant above a leaf axle. This will encourage the plant to re-sprout closer to the ground and will give you a sturdier plant with stronger, longer stems. It is tempting to only cut the stem length that you want, but in the long run, cutting deeper into the plant will give you an overall healthier and more productive plant. Once you’ve harvested your flowers, recut the stems and place them in cool water in a clean vase of your choice. For the longest vase life keep them in a cool location out of the direct sun. Dahlias typically have a vase life of 3-6 days depending on stage of harvest and type of dahlia.

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Winter Care & Storage
Dahlias are perennials, however, in colder climates the tubers are dug up for storage each winter. Here in Victoria you can either dig the tubers up for the winter or protect them with a thick layer of mulch overtop to insulate them. It is important to remember that dahlia tubers are prone to rot, so if your soil holds a lot of water over the winter it’s best to dig them up to avoid losing them. Once the first frost hits your dahlia plants will turn black. Once the foliage has turned black you should cut back the foliage to 6 inches.  It is best to wait for about two weeks after the first frost to dig up your dahlias. This waiting period cures the tubers so they will store over winter better. After the two-week curing period, carefully dig your tubers out with a digging fork. They should be left uncovered in a cool spot with good ventilation for up to two days to allow them to dry. Do not place them directly on concrete at this time as the concrete will desiccate your tubers. Once they are dry you can cut off the thick stems and pack the tubers in newspaper, peat or perlite and place them in crates to overwinter. These crates should be kept in a cool spot that stays around 5-10 degrees. A basement or garage is ideal, as long as it won’t freeze. If your storage space is prone to moisture you might consider occasionally putting a dehumidifier on. In the spring you can bring your dahlias out of storage and plant them again for another season of beauty!

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FAQ

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I received my tubers… now what?
Keep your tubers in the bag until you are ready to plant them. Keep the bag in a cool place, a garage is perfect. Most importantly keep them out of any glaring sunlight and definitely not right next to a heater.
Tubers ideally should be planted out from late April till late May. A little bit of this depends on your location. If you’ve got a sunny spot with good drainage, late April is the perfect time to plant them. If your soil tends to hold lots of water it’s best to wait till it dries out a bit. 

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Why are some of my tubers bigger than others?
In the world of dahlias, size doesn’t really matter! As long as you start with a firm tuber that has all of the parts (crown, neck, tuber) mentioned above your plant should grow happily if given the proper care. Often you will see sprouts starting to emerge from the crown.

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Can I grow dahlias in a patio pot or container?
Dahlias prefer a little space to stretch out their roots. I always recommend that you grow dahlias in the ground, but know that’s not always possible. If you are growing in containers try to provide the largest container possible and give your dahlia lots of compost at the start of the season and feed with an all purpose fertilizer throughout the season.
 

What are the best dahlias for pollinators?
Dahlias can be a bit of a conundrum for pollinators. Their tight decorative petals don’t offer a lot of room for pollinators to get in there. Open faced dahlias like collarettes and singles are the best as they allow pollinators easy access to the centre. If you really want a ball dahlia but also want to help out the pollinators, leave the flowers on the plant till the middle opens up, ie: don’t deadhead.

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Do dahlias need full sun?
Yes, dahlias prefer a location with full sun. They will take a partial shade but will ultimately bloom best in full sun.

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What if there is a bit of mold on my tuber?
That’s totally fine. They have been hibernating all winter in my garage and a little mold is inevitable. As long as the tuber is not mushy, you’re good to go. Just give the mold a wipe off before planting. If you are concernes about it you can dip your tubers in Cinnamon. Cinnamon is a natural anti-fungal and I often dip my tubers in it while I’m dividing them.

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Got another question not answered above? For any questions or concerns feel free to reach out to us at flowerfacefarm@gmail.com

 

Thanks for supporting local flower farms and happy growing!