Want to get a head start on your dahlia plants for the season? Want to test your tubers for viability? A pre-sprout test is the way to go.
First, I will talk about the fastest way to test for tuber viability. Perform a pre-sprout test for viability if you are not sure that your tuber has eyes. I basically never do this on the farm. This is simply because I can tell which tubers are going to grow, just by inspecting their eyes. Of course, this takes some practice. You can learn how to identify eyes on your dahlia tuber, here. Still aren’t sure? Then a pre-sprout test is the best way to give the dahlia a chance to prove its abilities.
Second, I will share a great way to get a head start on your dahlias for the year. Start dahlias in pots in a protected space. Then, transplant them out into the garden. You could get blooms around 4-6 weeks earlier than otherwise.
Note that when you begin any type of pre-sprout test on your tubers, you have activated the growth of the tuber’s eyes. This means you can no longer return them to storage in a cool dark place. In other words, they must be planted and cared for. This is a pretty good reason to not start this process too early. Unless you are happy to have some dahlia houseplants (or greenhouse plants) until your “last spring frost date” (frost safe date).
Dahlia tubers are a gardener’s secret weapon for achieving an eye-catching display of colorful blooms. By pre-sprouting the tubers indoors early in the season, you can get your dahlia plants off to an early start. This gives them a longer growing season resulting in bushier plants and more flowers.
Sprouting your dahlia tubers ahead of planting accomplishes two important things
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It allows you to test the tubers for viability, so you don’t waste time planting dead tubers
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It gives the tubers a head start, so you get flowers faster once planted in the garden.
Read on to learn all the ins and outs of sprouting dahlia tubers. With just a little effort and planning, you’ll be rewarded with a gorgeous dahlia display.
When to Start Sprouting Dahlia Tubers
You’ll want to sprout your dahlia tubers about 4-6 weeks before your last expected spring frost. This gives the sprouted tubers time to develop roots and leaves before being moved outside.
If starting too early, the sprouts may get leggy or damaged if kept indoors too long. Be patient and wait until the optimal sprouting window for your climate.
Check Your Hardiness Zone
To determine your last spring frost date, search for your hardiness zone and “last spring frost” online. Another option is to check with your local nursery or extension office.
If you already grow vegetables or annuals, base the timing on when you safely plant those. The timing will be similar for sprouting dahlia tubers.
How to Sprout Dahlia Tubers
Sprouting dahlia tubers is simple and only requires a few supplies. Here is a step-by-step guide:
Supplies Needed
- Dahlia tubers
- Shallow tray or container
- Seed starting mix or potting soil
- Plastic bags (optional)
- Labels
Steps for Sprouting
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Fill tray: Fill a shallow tray or container with moistened seed starting mix or potting soil. Depth should be 3-4 inches.
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** Arrange tubers:** Place tubers horizontally in the soil, eye side up. Space 1-2 inches apart.
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Cover tubers: Cover tubers with 1-2 inches of soil.
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Label varieties: Label varieties using plastic tags or permanent marker on plastic bags covering tray. This prevents mixing up varieties later.
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Keep soil moist: Keep the soil moist but not sopping wet. Dahlia tubers rot easily.
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Provide warmth: Maintain temperatures around 70°F. Heat mats work well for this.
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Provide light: Once sprouts emerge, provide 14-16 hours of light. Sunny windowsills or grow lights work well.
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Watch for sprouts: Check for sprouts emerging in 2-4 weeks. Healthy sprouts will be firm and white, pink or purple. Discard any mushy or black tubers.
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Transplant outdoors: After the last spring frost, transplant sprouted tubers into the garden!
Caring for Sprouting Tubers
Proper care while sprouting dahlia tubers prevents problems like rot, weak growth or leggy sprouts. Follow these tips:
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Provide consistent warmth around 70°F for good sprouting. Fluctuating temperatures delay emergence.
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Water carefully and avoid overwatering. Damp (not wet) soil is best.
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Once sprouts emerge, increase light to 14-16 hours daily. Supplement with grow lights if needed.
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Provide air circulation with a fan to prevent damp-off disease.
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Watch for pests like fungus gnats, slugs and mites which can damage young sprouts.
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Transplant sprouted tubers to the garden quickly to avoid leggy or damaged growth.
Tips to Encourage Strong Sprouts
Here are a few tricks to get the strongest sprouts possible from your tubers:
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Start with high quality, fresh tubers from a reputable source. Old or damaged tubers may not sprout well.
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Choose plump, firm tubers showing no signs of shriveling or mold.
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Sort tubers by size. Larger tubers produce more robust sprouts.
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Dust tubers with a fungicide prior to sprouting to prevent rot and fungi.
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Avoid letting tubers dry out or accumulate excess moisture during sprouting.
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Move sprouted tubers to larger containers if they become crowded and struggle to emerge.
Transplanting Sprouted Tubers to the Garden
Once all danger of frost has passed, it’s time to move sprouted tubers into the garden! Follow these tips for successful transplanting:
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Harden off sprouted tubers for 7-10 days before transplanting. This transitions them from indoor to outdoor conditions.
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Transplant on an overcast day or in evening to prevent wilting. Water tubers thoroughly after transplanting.
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Take care not to damage the fragile sprouts and emerging roots when transplanting.
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Plant sprouted tubers at the same depth they were sprouting indoors, about 4-6 inches deep.
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Space plants 12-24 inches apart depending on variety size. Tall varieties need more space.
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Stake taller varieties to support top-heavy plants once they mature.
Troubleshooting Sprouting Problems
If your dahlia tubers fail to sprout or sprouts are weak and leggy, here are some common issues and solutions:
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Rotting tubers: Soil is too wet. Improve drainage and cut back on watering. Discard any rotten tubers.
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Small or no sprouts: Temperatures are too cool or light levels are too low. Move to a warmer spot and increase light exposure.
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Leggy sprouts: Light is insufficient. Provide 14-16 hours of direct light daily. Supplement natural light with grow lights.
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Pale sprouts: Let sprouts green up for 7-10 days before transplanting. Protect from harsh sun initially after transplanting.
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Wilting sprouts: Tubers are drying out. Maintain evenly moist soil. Transplant wilted sprouts immediately and water well.
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Weak or dying sprouts: Damping off disease is present. Improve air circulation and reduce watering. Disinfect trays and tools to prevent spread.
Get an Early Start for Maximum Flowers
Pre-sprouting dahlia tubers requires some forethought and effort. But it pays off all season long with earlier blooms, longer flowering, and a bounty of gorgeous flowers. Test your tubers for viability, encourage strong sprouts, and transplant to the garden on time. Then get ready to show off your magnificent dahlia display!
To Test Your Tubers for Viability
First, find a tray or container that will hold about six inches of soil. Put this tray in a place where the soil temperature will not drop below 60 °F/ 16 °C. Next, spread about two inches of lightly dampened soil along the bottom. Be sure that the soil is not too wet, otherwise the tubers will rot.
Then, line up all of your tubers horizontally. Be sure to label and keep track of which tuber is which. At this point, space does not matter, because the tubers will be transplanted. So, you can put a ton of tubers into this container.
Cover them with the remaining soil so there is about an inch on top. Do not water, assuming you started with damp soil. Remember, dahlia tubers are very prone to rotting. Note that it is better for the soil to be on the dry side, than on the wet side (once you have a growing plant, water regularly, of course).
Your dahlia tubers will quickly begin to sprout. In a week, dig out the tubers and see what’s happening. Bury the ones that haven’t sprouted eyes. Give them another week, and check again. Give up on tubers after 3 weeks of no sprouts. Eyes can be white, pink, or purple.
Immediately transplant the sprouting to deeper pots, so the tubers are covered in about five inches of soil. Be sure to time this correctly. If they are not moved to a more permanent home (outside into the garden, or perhaps to a deeper container, planted 5 inches deep), then they will grow leaves at a shallow depth and will not make healthy plants. Remember, when you transplant them, use lightly damp soil and do not water until growth begins to appear. Plant the sprouting tuber 5 inches deep, horizontally. Once the leaves pop out of the soil surface, begin watering regularly.
To Get a Head Start on Your Dahlia Season
If you want to get a head start on your dahlias, consider planting your dahlias into small pots. I use one gallon pots. Larger will work well too. Dahlias need to be started in an environment where soil temperatures will be maintained at or above 60 °F/ 16 °C. They also need access to sunlight as soon as they begin to sprout out of the ground. A greenhouse, hoop house, or sunny windowsill are great places.
It typically takes about two to four weeks for dahlias to begin to sprout up out of the soil. So start this process between five and seven weeks before when you expect to be able to plant them outside.
This method is best for people with smaller amounts of dahlias, just because this is a lot of extra labor for the dahlia farmer. The benefit is that you will get blooms typically 4-6 weeks earlier. Other options for getting blooms earlier include planting in raised beds, under floating row covers, or in hoop houses.
Start with about two inches of damp soil. Again, remember not to use soil that is too wet. Otherwise, your tubers will rot before they establish a root system. Plant the tuber horizontally with the eye facing up toward the sky.
Cover in five inches of soil. Do not water until greens begin to appear.
Once your outdoor soil temperatures have warmed to 60 °F/ 16 °C, transplant your happy dahlia plants out into your garden.
Dividing Dahlia Tuber Clumps & Pre-sprouting Dahlia Tubers to Take Dahlia Cuttings
FAQ
How do I wake up my dahlia tubers?
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1. Move from Storage:Take the tubers out of their winter storage (e.g., a cool, dark basement).
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2. Warm Environment:Place them in a warm, frost-free location, preferably between 65-70°F (18-21°C).
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3. Humidity:Keep the humidity high, as this can help the eyes sprout and encourage growth.
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4. Light (Optional):While light isn’t strictly necessary for sprouting, exposing the tubers to some light can encourage faster growth and development.
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Fraylick Farmhttps://fraylick.comWaking Up Your Tubers – Fraylick FarmMar 14, 2024 — It’s very simple- Take your tubers from their storage location and move them to a frost free place that’s around 65-70 degrees. A little warmer is o…
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Garden Bee Flower Farmhttps://mygardenbee.comPre-sprouting Dahlia Tubers – Garden Bee Flower FarmJan 28, 2021 — All you need to do is take your dahlias out of winter storage and move them to a warm room that is above 55 degrees. You want to keep them in the st…
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5. Moisture:Ensure the tubers are not dry. If they seem shriveled, you can lightly moisten the storage medium (e.g., peat moss).
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Garden Bee Flower Farmhttps://mygardenbee.comPre-sprouting Dahlia Tubers – Garden Bee Flower FarmJan 28, 2021 — All you need to do is take your dahlias out of winter storage and move them to a warm room that is above 55 degrees. You want to keep them in the st…
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Wallish Greenhouseshttps://www.wallishgreenhouses.caBringing Dahlia Tubers Back to Life – Wallish GreenhousesMar 10, 2020 — If you kept your Dahlia in a pot through the winter, bring the container into the light and warmth & give it just a little water, like 2-4 cups. You…
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Two Sisters Flower Farmhttps://twosistersflowerfarm.comHow to Save Dahlias for Another Year!If you find that your tubers look shriveled + dehydrated, try adding more moisture into your space either by moving your tubers to a new location or using a med…
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butternutgardens.comhttp://butternutgardens.comSTORING YOUR DAHLIAS – PART FOUR OF A FOUR-PART SERIES ON OVERWINTERING DAHLIAS — Butternut GardensNov 17, 2018 — I have tried three separate methods over the years. One method is to put your tubers in peat moss, which is slightly damp. A fresh bag of peat moss …
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6. Patience:It can take a few weeks for the tubers to fully wake up and sprout. Once you see sprouts, you can consider planting them in the ground or in pots, says Epic Gardening.
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YouTube · Budget Gardening with Vita Locahttps://www.youtube.comHow To Plant Dahlia Tubers || Waking Up Pre-Sprouting DahliasMar 23, 2025 — I’ve never done it but it’s definitely doable you want to dig a hole that’s about 4 to 6 in in depth next you want to place your tubers. so that the…
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Do I need to soak dahlia tubers before planting?
- Place the tubers in a bucket of lukewarm water.
- Let them soak for about an hour.
- Plant the tubers as usual.
How long does it take dahlia tubers to sprout?
- Variety: Some dahlia varieties are naturally faster to sprout than others.
- Temperature: Warmer temperatures, especially soil temperatures, accelerate sprouting.
- Soil Conditions: Well-draining, fertile soil is essential for healthy growth and sprouting.
- Moisture: While tubers don’t need excessive watering initially, maintaining adequate moisture is important.
- Planting Time: Planting later in the season, when the soil is already warm, often results in faster sprouting.
How do you grow dahlia tubers?
Dahlia tubers need well-drained soil with plenty of compost and enough sunlight, water, and fertilizer for optimal growth. For the best results, it is recommended to start the process in the early spring when the soil temperatures are between 50-65F. Plant the tubers 4-6 inches deep and 8-12 inches apart in well-drained soil with plenty of compost.
Do dahlia tubers sprout?
With the right conditions, dahlia tubers will sprout and produce beautiful flowers that will brighten any garden. When it comes to getting dahlia tubers to sprout, the key is to start the process in the early spring when the soil temperatures are between 50-65F.
How do you grow Dahlia sprouts?
Bury tubers horizontally just below the mix surface. Don’t cover them. Check weekly for sprout development. Discard any tubers that haven’t sprouted after 3-4 weeks. They likely won’t grow. Once a tuber starts sprouting, you know it’s viable! Transplant it into deeper pots immediately to encourage stronger growth. What Do Dahlia Sprouts Look Like?
How long does it take a dahlia to sprout?
Of course, once you have a plant that is growing, you will need to water it often. Your dahlia tubers will quickly begin to sprout. In a week, dig out the tubers and see what’s happening. Bury the ones that haven’t sprouted eyes. Give them another week, and check again. Give up on tubers after 3 weeks of no sprouts.
How do I Stop my dahlia plant from sprouting?
Leaving sprouts to grow will weaken the dahlia plant once planted. If your stored dahlia tubers have started into premature growth, take steps to stop continued sprouting: Move tubers to a colder area – Get the tubers into temperatures below 50°F. A garage, shed, or unheated basement area works well.
Can a dahlia plant grow if nipping off sprouts?
Nipping off sprouts now won’t affect the tuber’s ability to grow come spring. However, any growth at this point takes energy away from the tuber’s food reserves. The tuber needs that stored energy to grow a strong, healthy plant later on. Leaving sprouts to grow will weaken the dahlia plant once planted.