FROM BUD TO BLOOM
a Dahlia’s Guide to Looking Fabulous
So, you've received your dahlias, lucky you! But now what?
Follow along for tips and tricks to ensure your tubers get the best possible start.
First Things First: Storage
Until you're ready to plant, keep your dahlias dormant in a cool, dark place—ideally between 4–8°C. Too cold, and they'll freeze (and a frozen tuber is a goner).
Waking the Hunnies Up
At Havenley Farm, we like to give our dahlias a head start. Why risk planting duds in the field when you can wake them up a little early?
Roughly 3 to 4 weeks before your region’s last expected frost, give your tubers a head start indoors. Nestle them into slightly moist soil inside a ziplock bag and keep them in a warm room—around 20°C should do it nicely. This little trick convinces the tuber it's been planted, jumpstarting root development. Early root growth not only boosts vigor once planted out, but also offers a bit of insurance against any surprise spring downpours. Think “moist,” not “marinated - do not water.
Get your soil tested now so you know how to amend your beds for optimal growing. The pH level of the soil should be 6.5-7.0, slightly acidic. To adjust the pH level in your soil you may add Lime to increase your pH level, or Sulfur to decrease your pH level a month ahead of planting.
Bring on the SPF
Once the weather warms up... slowly introduce your dahlias to the great outdoors. This is called "hardening off"— moving them outside for a few hours each day to acclimate. Skip the scorching midday sun and let them enjoy a little fresh air and filtered light. Once the risk of frost has past and the soil temperature is around 15°C, plants are now feeling confident and are ready to go party.
Let's Talk Planting
Your dahlias are ready for their big debut. Dahlias thrive in fertile, well-drained, slightly acidic soil. Think rich, fluffy, and full of nutrients. If your soil needs a little help, amend it with compost, aged manure, or a balanced fertilizer. I plant our tubers with a handful of blood meal for season starter nitrogen insurance on top of the organic soil amendments (after testing our soil, of course). Whether you’re planting in garden beds, raised beds, or containers, make sure they’ve got what they need to succeed. They are heavy feeders all season long. Plant horizontally, with the growing eye facing up and cover it.
Planting in pots?
No problem—just make sure your containers are at least 5 gallons in size. Dahlias are not fans of cramped dorm rooms.
When your dahlias are 6-8 inches tall, find the middle stem and pinch it out above a set of leaves. This will hurt to do, but in return it will cause the plant to send out lateral stems yielding 5-10x more blooms!
Label your plants NOW (we write directly on the tuber using a garden marker) then again at planting and again with a neck tie label once the stalk is mature enough to handle a necklace.
Timing is Everything
Dahlias need 120 days to grow and develop tubers, so don’t delay—get them in the ground as soon as the risk of frost has passed and the soil begins to warm. We plant early to mid May / Mother's Day keeping it safe. Well draining soil is essential.
Plant in full sun, pretty please.
While they can tolerate a bit of shade, dahlias are true sun lovers. A location with full sun all day will give you the best blooms. If you plan to show your blooms, you will want a bit of afternoon shade.
Think Aperol Spritz & St. Tropez
Once the dahlias sprout and new roots form, you can begin regular watering. Overwatering too early is a fast track to rotting tubers.
I like to plant in colored groups of the same variety about 4 - 6" deep and 12" apart. We drip water every second day once they are established.
One of the most common mistakes dahlia growers make is overfeeding with high-nitrogen fertilizers mid-late season. While nitrogen is essential for plant growth at the beginning of the season, too much of it can lead to problems: floppy stems, oversized leafy plants, undersized blooms, or worse—no blooms at all. Mid- Late season, Epsom salts and potash can benefit dahlia plants by providing essential nutrients and improving overall health mid-season. Epsom salts, rich in magnesium, can help dahlias utilize nitrogen more effectively and enhance leaf color, while potash, particularly in the form of sulfate of potash, promotes strong flower development and vibrant blooms. No more nitrogen once you see blooms!
Grab Your Fork—It’s Dahlia Digging time
Getting ready to dig? Time to cue the countdown.
About a week before you plan to dig up your dahlias, cut the stalks down (assuming they are all properly labelled) to about 4–6 inches above the soil—just enough to give you a good handle when it’s time to lift the clump. Leaving the clumps in the ground for a few extra days can help the "eyes" (the little growth points) swell and become more visible, which can make dividing easier later on. Will it boost storage success? Maybe. Is it absolutely necessary? Not at all.
That said, if the weather’s about to turn soggy or your soil drains poorly, go ahead and dig them up right after cutting the stalks. Wet, heavy soil is no friend to a dahlia tuber - cue the suction and snapping sounds. Leave generous room around the stalk while digging (12-14") to avoid slicing the tubers in half. Gently lift and set aside to be washed. Feel free to chuck in some organic matter like compost, well-rotted manure, or leaf humus into the hole getting ahead on soil amending for the following spring.
And while you're at it, keep an eye out for signs of disease, especially crown gall or leafy gall—often visible around the crown of the plant. It’s not the most glamorous part of dahlia season, but catching problems now can save you some serious headaches later.
Multiply your Magic
Easier watched than explained. Once washed, some clumps will be harder to divide - but this is how it's done.
Tuber TLC
After you’ve divided your dahlias, give the freshly cut tubers about 24 hours to air dry and form a callus. Think of it as them toughening up for their long winter nap. Just don’t forget about them—leave them out too long and they may start to soften and shrivel (some varieties are drama queens and some are more sensitive than others).
Once dry, pack them up for storage and nestle the tubers in your storage medium of choice. At Havenley Farm, we use a vermiculite/ peat moss combo because it’s easily accessible in our area, but whatever you choose, make sure it’s just barely damp—not moist. If it’s too wet, you’re rolling out the red carpet for rot.
Pack the tubers in loose layers, keeping each one separated by the storage medium—no snuggling allowed. Leave the lid off the container for a week or so to allow any access moisture escape.
Then, move them into their cold, dark winter hideaway—somewhere around 4–8°C is ideal.
But don’t just set it and forget it!
Check in on them frequently through the winter. Look for condensation (a sign they might need some air), or signs of drying out, like wrinkling or shrivelling (which could mean humidity is too low or it’s getting too warm). Make small adjustments to keep them happy until Spring.