When it comes to gardening, there always seems to be something new to learn. Even experienced gardeners may not know what to do with dahlia bulbs after they have flowered. If you’re wondering the same thing, don’t worry – you’re not alone! Although dahlias are not particularly high maintenance, learning what to do with dahlia bulbs after flowering will ensure that they return to brighten up your garden year after year.
What are Dahlia Bulbs?
Dahlias do not actually have “bulbs” in the traditional sense. Instead, they grow from tuberous roots, often simply referred to as “tubers.” These tubers are fleshy, elongated structures that store nutrients and energy for the plant. They are similar in appearance to a string of potatoes or sweet potatoes connected together.
Here’s a breakdown:
- Tubers: Dahlia tubers are the underground storage organs of the plant. They store energy in the form of starches that the plant uses to grow and bloom in the subsequent season.
- Eyes: On each dahlia tuber, you can often find small growth points called “eyes.” These eyes are where the new stems will emerge in the spring.
- Neck: The tuber’s “neck” is the slender part that connects the tuber to the main stem of the dahlia plant.
- Difference from Bulbs: Unlike bulbs, which are layered (like an onion), dahlia tubers are solid. Bulbs, such as tulips and daffodils, have a layered structure, while tubers are more uniform in texture.
What to do with Dahlia Bulbs after Flowering?
As we mentioned previously, dahlias are low maintenance and with the right care, they will continue to come back year after year. Leaving dahlia bulbs in the ground is likely to be the easiest option and you do not require any kind of technical skill to be able to do this although there are a couple of minor things that you will need to think about. If, however, you live in an area that experiences extreme cold, dahlias will need to be lifted and stored inside and replanted in the spring.
Step 1 – Remove Stem and Dead Head
As soon as the flower has faded and died, you will want to remove the stem and the faded bloom. This is to conserve the plant’s energy stores as the next stage in the plant’s life cycle would be trying to create seeds.
Step 2 – Leave the Foliage in Place
When removing the stem, be careful to leave the foliage in place until it dies back on its own. The leaves will continue to absorb energy from the sun and through photosynthesis, the sun’s energy is converted into vital sugars that are stored in the bulb for the following season.
Step 3 – Leave Alone
Once all the foliage has died back and the bulb has once again become dormant, there is nothing left for you to do. There is no need to water the area or tend to it at all until you fertilise it in the early spring. I did tell you that dahlias were low-maintenance!
How to Lift and Divide Dahlia Tubers?
Every 3 to 4 years, dahlia bulbs will self-propagate into clusters that can be separated to form new bulbs.
Steps 1 & 2
Steps 1 & 2 are the same as above. You will want to ensure that you remove the stem and deadhead the flower but continue letting the foliage continue to grow and absorb sunlight, therefore, refuelling the bulb’s energy stores.
Step 3 – Lift Your Bulbs
Once the foliage has all but died back, you can lift your tubers. Dig an area around the bulbs being careful not to scratch or scar them as this open wound can leave your tuber susceptible to disease and rot.
Step 3 – Clean Your Bulbs
Once your bulbs have been lifted, they will require a clean. It is best to do this with a soft brush. Gently shake off any excess soil and then using a soft brush, give the tuber a gentle clean and inspect for any damage or disease.
Step 4 – Divide Your Tubers
Once you have lifted your bulbs and brushed them off, you will see where the new bulbs have formed, and you will be able to just gently break these apart with your fingers.
Step 5 – Store Your Tubers for Winter
After dividing the tubers, it’s essential to store them properly to ensure they remain viable for the next planting season.
Important: It is best to replant all of your bulbs old and new immediately in the places you wish them to grow next year.
How to Store Dahlia Bulbs?
Dahlia’s do not like a heavy frost so if you have decided to lift them, your dahlia tubers will usually keep for a while with no problems. We recommend using a cardboard box for storage as this will let them breathe as using plastics can cause the tubers to sweat and rot.
Here are some additional tips:
- Curing: Before storing, let the divided tubers dry in a well-ventilated area, away from direct sunlight, for about a week. This process, known as curing, helps harden the tubers and reduces the risk of rot during storage.
- Labelling: If you have multiple dahlia varieties, it’s a good idea to label each tuber or group of tubers with the variety name or colour to avoid confusion when replanting.
- Packing: Place the tubers in boxes or containers filled with slightly moistened peat moss, vermiculite, or sand. Ensure that the tubers are not touching each other to prevent the spread of any potential diseases.
- Storage Conditions: Store the containers in a cool, dark, and frost-free place, ideally at a temperature of 4-10°C. Basements, cellars, or garages can be suitable storage locations, provided they remain frost-free.
- Check Periodically: Throughout the winter, periodically check the tubers for any signs of rot or shrivelling. If you notice a tuber starting to shrivel, lightly mist the storage medium to increase humidity. If you find a rotten tuber, remove it immediately to prevent the spread of disease.
- Replanting: When spring arrives and the threat of frost has passed, your tubers will be ready to be replanted in the garden. Before planting, inspect the tubers one last time, discarding any that show signs of rot or disease.
Read More: How to Overwinter Dahlia’s in Pots
Dahlia bulbs (tubers) are extremely low maintenance and do not really take much in the way of looking after them. As long as you let the leaves continue to grow after the flower has gone, they will still be able to store enough energy to flower the next spring. Many people will just mow over the leaves once the flower has gone but this is not a good idea as you will end up with stunted dahlias the next spring and that is if they even grow at all. If you need to lift and store your dahlia tubers, it is not too difficult either providing you follow the steps that we have laid out for you, you will have beautiful dahlias year after year.
Garden Doctor Tips
“Replant stored tubers in early spring once the ground has thawed!”
“Do not forget to leave the foliage in the ground until it dies back on its own. The tubers need the foliage for photosynthesis!”
“Over time, dahlia clusters will expand. Lift and separate the tubers every 3 years and plant a few elsewhere to establish new clusters!”
“If storing dahlia tubers for winter, check on them every 4 weeks to ensure that none of them have rotted and gone mushy, if any have, throw them away immediately!”
Frequently Asked Questions
How many years do dahlia bulbs last?
Dahlia bulbs do not really like to be out of the ground but those that are in storage and cared for properly will last around 12 months before they require planting.
Do you have to dig up dahlia bulbs every year?
No, dahlias do not need to be lifted every year. Dahlias will do fine being in the ground through the winter although it is a good idea to lift bulbs every 3 or 4 years to separate the bulb clusters.
Can dahlia bulbs be left in pots?
Yes, dahlia bulbs can be left in pots as long as they are planted deep enough and are protected from heavy frost.
Trevor Wright is not just a seasoned horticulturist; he’s the esteemed Garden Doctor. With a BSc in Horticulture and years of hands-on experience in the soil, Trevor has become a trusted mentor for all things gardening. As the founder of Garden Doctor, he’s committed to clarifying the intricacies of gardening, offering straightforward advice that’s rooted in years of practice. His writing is a garden of how-tos, savvy insights, and comprehensive guides that enable individuals to nurture and grow their garden dreams. When he’s not knee-deep in garden beds, Trevor is at his keyboard passing on his green-thumbed wisdom to budding gardeners, ensuring that the legacy of sustainable and joyful gardening blossoms far and wide.