Our dahlia digging and storing project continues at the farm.
Dahlias are frost-tender tuberous plants that can overwinter outdoors where the weather is mild. However, here in the Northeast, severe winter conditions will cause them to split and rot, so they must be pulled from the ground and stored away every fall. Several days ago, my gardeners uprooted all the dahlia tubers, rinsed them and set them inside the temperature and humidity-controlled greenhouse where they could cure. Now, they are ready for storing.
Enjoy these photos and tips.
Since dahlia plants only thrive as far north as USDA plant hardiness Zone 9, cold-climate gardeners must dig up and store the tubers each year.
Dahlia tubers – sometimes referred to as “bulbs” – are not true bulbs at all, as they differ in both appearance and growth function. Bulbs are round and consist of one swollen root. Tubers, come in a variety of shapes and form in a cluster. They also grow out of the “eyes.”
Here is a closer look at the hollow stem. It is completely dried through. If you don’t have a temperature and humidity-controlled greenhouse, these tubers can dry outside if there is no rain forecasted or in any room that does not get any direct sunlight. The drying process could take up to a couple of weeks.
Ryan inspects each dahlia tuber and trims away any parts that are rotten. He also checks the “mother” tuber or the original tuber that was planted, which is more likely to rot than the new ones.
Just to be sure, Ryan also writes the variety of the dahlia on one of the tubers, so there is absolutely no confusion later.
Next, Ryan trims the stem slightly, so it is just about two to three inches long.
Ryan coats any cut side with Douglas fir bark dust. This dust helps to heal the sliced area, so it doesn’t shrink or curl. The slightly acidic bark is also a natural fungicide and moisture buildup barrier that will help deter rot. Come spring, the dust can be left on it when planted to thwart decay before they sprout.
You can find fir bark dust in some specialty garden shops or online. You can also use sulfur dust in the same way.
Ryan also generously coats the freshly cut stem.
All those mesh bags saved from our bulb orders come in handy for storing tubers. These bags come in a variety of sizes and provide lots of air circulation. If you don’t have any mesh bags, any well-ventilated bags or boxes will do.
Ryan places each tuber clump in a bag and surrounds it with wood shavings. Some gardeners prefer storage mediums such as vermiculite, coarse sand, sawdust or sphagnum peat moss.
Because we also use wood shavings down in my stable, we have a good supply here at the farm.
Ryan adds enough shavings to keep the tuber dry. This is important as any moisture that causes rot could spread to other tubers.
We also save all the plastic crates that come whenever we order large collections of bulbs. I always try to reuse, repurpose or recycle everything at the farm.
The bags of tubers are then placed into a crate.
Ryan places the marker in the bag, so it is ready when spring arrives and time to re-plant the tubers.
It is important to ensure each bag gets ample air circulation – in the bags and in the crates. Overcrowding may promote rot.
Ryan does this process for each and every clump of tubers. He checks and trims any rotten pieces and feels each tuber. They should all feel firm to the touch.
Here’s Gavin carrying each crate down to the basement greenhouse. The ideal storage temperature is above freezing but below 50 degrees Fahrenheit.
Be sure to check the tubers a couple times over the winter, and discard any that have rotted. Environmental changes in the storage location, such as increased humidity or fluctuating temperatures, can still damage overwintering dahlia tubers. And then next spring, they’ll all be taken out again for planting – I can’t wait.
If you live anywhere but the warmest regions of the United States, it’s time to dig up and store those precious dahlia tubers.
When in bloom, dahlias provide some of the garden's biggest and most spectacular flowers in many different sizes, forms, and colors. This year, my dahlias were especially productive - I made dozens of arrangements for my home. However, native to Mexico, dahlias are not winter-hardy and tend to split in freezing temperatures or mold in soggy, wet soil. This week at my Bedford, New York farm, my gardeners dug up all the dahlia tubers, so they could be stored indoors for the cold season.
Here is our step-by-step process. Enjoy these photos.
Wait until the foliage has turned yellow and brown before digging up the tubers. This is important so that the plant can gather energy for the following year. It will store starches in the tuber which will fuel initial sprouting in summer. The best time is a couple weeks after the first frost when they’re well into dormancy yet haven’t been harmed by the cold.
First, Ryan cuts all the stems down leaving about five to six inches of the main stem. These stems will be used to hold the tubers as they are lifted from the soil.
Dahlia stems are hollow making them quickly susceptible to rot. This is also why dahlias often have to be staked to help support their very large flowers.
Phurba digs up the dahlia tubers with a garden fork starting about a foot away from the center stem. He is very careful not to let the tool come into contact with any of the tuberous roots, which can be easily damaged.
I always say to “use the right tool for the right job.” My Martha Stewart garden forks from QVC are perfect for digging up our dahlia tubers. They come in sets of three, each with a fork, a shovel, and a spade for tilling, turning, and transplanting anything in the garden. https://qvc.co/377bklz
Phurba loosens the soil around the dahlia tubers by thrusting the fork into the ground and then slowly prying up the soil freeing the tubers.
With one hand on the stem, Phurba gently removes the entire mound from the ground.
Dahlia tubers consist of a stumpy stem with several swollen sections attached to it. Phurba pokes the clump gently to knock off most of the dirt.
Phurba and the others work in an assembly line fashion, so the task is done quickly and efficiently. While Phurba digs up the tubers, Gavin removes the cut plants from the area.
All of these dahlia tubers have been safely pulled and are ready to be rinsed.
Next, Phurba washes the dirt off the dahlia tubers by hosing them down. If you’ve already put the hoses away for the season, you can also swish the tuber around in a bucket of water. Be very gentle—even the slightest puncture can introduce pathogens, causing the dahlia bulbs to rot in storage.
Tuber productivity varies between varieties. Here, Ryan shows how small the tuber was when planted, and on the right, how much it has grown. Each clump pulled had anywhere from five to 20 tubers. Not all will have full eyes allowing them to grow a stem next spring, but we definitely harvested more than we planted.
Here is a clean clump of dahlia tubers with their roots intact.
To dry the dahlias, we use shallow plastic mesh trays like these that provide good air circulation. They’re available at Johnny’s Selected Seeds and can be ordered in multiples of five. https://bit.ly/355EPCu
Phurba carefully rinses all the dahlia tubers and leaves them in place until they are collected by the variety and put into trays with appropriate labels.
All the tubers will look similar, so it is crucial to keep them with their individual markers. These tubers are ‘Penhill Watermelon’ dahlias – a dinner plate variety with a giant fluffy mix of peach, lavender and the tiniest hint of yellow flowers.
Dahlia ‘Kelvin Floodlight’ is also a dinner plate variety – a butter-colored flower that grows up to 10-inches across.
This day was very rainy and wet, but these tubers are rinsed and waiting to be placed into trays.
Here are all the cut dahlias ready to be carted to the compost pile. Here it is easy to see what they look like after the first frost – all the foliage has darkened and died.
Before they are bagged and stored, the dahlia tubers must dry completely. Ryan places all the trays of dahlia tubers into our small hoop house where they can cure properly. The curing process involves high temperatures and high relative humidity to prepare the roots and tubers for long periods of storage and to heal the skins wounded during harvesting.
Now this garden bed is empty and ready for planting the next crop. I wonder what it will be. How did you prepare your dahlias for storage? Share your gardening comments with me in the section below.
If you’re a passionate and serious gardener like I am, you know that soil is one of the most important factors in creating a healthy and productive garden.
Good soil provides plants with access to nutrients, water, and air. It stabilizes plant roots and helps the plants maintain a natural resistance to pests and diseases. Every year at my farm, we spend a good amount of time preparing the soil in the gardens for planting. This includes removing debris and old root systems, tilling the earth to break up large clods, and adding rich nutrients and compost. Not long ago, we worked on a new bed located in one corner of my lower hayfield. It’s a tedious process, but well worth the effort for the next gardening season.
Enjoy these photos.
I used to store smaller loads of compost here, but I decided to clean up the area and move the compost piles to the location where all the biodegradable matter is stored. It is a good spot for a garden because it has plenty of room and plenty of light. This past summer, we grew pumpkins in this space.
Across the field is my grove of weeping willow trees. I’ve planted so many trees here at the farm – I am always amazed at how much they grow and thrive here.
The first step is to rake up any remnants of vegetables and other roots and vines. This makes it easier for the rototiller to do its job and prevents anything from getting caught in the machine’s tines.
Pete also picks up any big rocks that would be in the way of the rototiller’s path.
Rototilling is one method of turning up the soil before planting. We rototill the vegetable and flower gardens every year – regular tilling over time improves the soil structure.
This is a Barreto Heavy-Duty Mid-Sized Tiller. On rear-tine tillers like this, wheels are standard operating equipment. This particular model has an 18-inch tilling width and uses hydraulics for easy maneuverability.
Pete starts tilling the beds on one side of the garden and goes up and down in rows from one side to the other mixing in any of the leftover compost as he goes.
The machine is set to till the soil at about six to eight inches deep. On some tillers, the speed of the rotating tines helps determine the speed of the machine.
As he moves, Pete makes sure to overlap his passes slightly, so every bit of soil is covered. Tilling also helps to level the ground as it turns over the soil.
The machine needs a lot of control to maneuver it through the soil beds, so Pete has to go slowly.
This is what the soil looks like once it is upturned. When this is done it is a good time to determine its condition – too much sand in the soil may make the soil too dry, and too much clay may make it too wet. The soil should be a good combination of earth, sand, and clay. My soil is very well balanced, but I always add extra nutrients to keep it as healthy as possible for my crops.
Only rototill when the ground is moist, but not wet – the soil should still crumble when picked up. And do this on a day when there is little or no wind, which could also slow down the task. And be sure to wear proper safety gear such as eye and ear protection.
On the right is soil that hasn’t yet been tilled. On the left – beautiful nutrient-rich overturned soil. If you are not sure what amendments the garden soil may need, test it. Kits are available at garden supply stores and online. It is very easy to do and tells exactly what the soil is lacking.
After a good portion of the area is tilled, Ryan starts sprinkling some lime over the entire bed.
Lime works to increase the pH of acidic soil. Lime also provides important plant nutrients, including calcium and magnesium; improves soil texture; and helps convert other soil nutrients into usable forms.
Garden lime is a powdered or pelletized product made from naturally occurring minerals.
Gavin also sprinkles super triple phosphate onto the tilled soil. Heavy rain was expected later in the day, so everything would be well absorbed.
Super triple phosphate increases root development and helps plant sugars move more efficiently for larger flowers and more fruits.
Here is Pete just finishing the last row with the rototiller.
Building up the soil is the most important part of preparing a garden for growing vegetables and flowers. Rich soil will encourage and support the growth of healthy root systems. I am looking forward to planting this bed next year.
Martha Pins
Martha Tweets
