In November, Martha Stewart shared a blog post about one of her favorite winter garden traditions: Protecting her beloved dahlia tubers without digging them up. Dahlias may appear like they’re fragile and can rip easily, but with the right care in winter, they can survive the frigid cold and bloom back to life come spring.
Martha’s method is actually quite simple and surprisingly doesn’t require much effort from the gardener. It’s perfect for the person who wants beautiful dahlias without the yearly ritual of having to lift and store the tubers.
Why Leave Dahlias in the Ground?
Dahlias are tender perennials, which means they can’t naturally handle freezing cold temperatures. Most gardeners dig up and store dahlia bulbs in their basement or garage in order to replant them when warm temperatures finally return.
Leaving dahlias in the ground allows the root system to mature undisturbed and saves the gardener time and guesswork in spring.
1. Start With a Thick Mulch Blanket
Start the winter process by cutting blackened foliage down to a few inches above the soil. After than is the most important step: insulation.
To do this, create a deep pile of mulch, around 8 to 12 inches (20-30 cm) high, over each clump of tubers. This could consist of shredded leaves, pine needle mulch, or straw. This keeps the soil temperature stable and protects tubers from the dreaded freeze-thaw cycle. Try this Premium Brown Pine Bark Mulch from Lowe’s. It offers excellent insulation and settles naturally over the winter months.
2. Add a Weather Shield
If winters where you live involve heavy rain, ice, or strong wind, adding a breathable cover will help. This plant cover from Amazon is for plants low to the ground, protecting them from sleet, snow, frost, and wind. It’s great for an easy, hands-off approach and works well if you live in a very cold climate. You can also buy a roll of burlap fabric from Amazon. Burlap is a favorite as it keeps the mulch in place while still allowing moisture and air to move through.
Bonus tip: If you use burlap, you can tuck a few evergreen branches leftover from the Christmas on top for a bit of extra protection and a cute holiday aesthetic.
3. Don’t Forget About Drainage
Cold can be challenging, but soggy soil is a whole other beast. Dahlia tubers rot easily when wet, especially in compacted soil, and even if they’re insulated. If your garden tends to stay damp in winter (say if you live in an area that gets a lot of rain), consider slightly raising your planting area or mixing in a coarse compost to help improve drainage.
This garden soil from Lowe’s works especially well as it loosens dense soil and helps drain water away from the tubers.
4. Mark Your Clumps for Spring
Your work isn’t completely done! Once you’ve tucked in your dahlias for the winter, place a marker next to each dahlia mound. Winter has a way of making you forget what is planted where, especially when it gets covered by snow and leaves.
What to Expect When the Weather Warms
Once spring arrives, we’re all so excited that it’s tempting to uncover everything right away. Resist this temptation! Pull back mulch gradually to protect the tender new growth, especially as you can still have unexpected frost, even in spring.
The tubers will sprout when the soil warms up, and if winter still causes some partial dieback, dahlias usually rebound quickly once they get going.
A Gentle, Sustainable Way to Garden
Martha Stewart’s hack for winter dahlia defense is a reminder that gardening doesn’t need to be hard labor. With a thick layer of mulch, breathable protection, and a little patience, you can keep your dahlias safe throughout the winter.
