Tips from Olle Garden Bed: How to Overwinter Dahlia Tubers (step-by-step guide)

Dahlia is the favorite of the garden, for good reason. They will bloom gorgeous and noisy flowers every year, but they must pay a price for their early amazing display. The following content also has some reference value for raised garden beds.

Therefore, after planting tubers in spring and pouring out in summer, there is an additional gardening work to be done in autumn: preparing dahlia for winter.

Can I leave my dahlia underground for the winter?

If you want them to be beautiful compost, you can. Well, maybe this is not what you want to hear, but this may happen if you don't dig out your dahlia tubers before the ground freezes.

Admittedly, some gardeners with warm climates may be able to leave tubers underground in winter. However, please remember that the Dahlia tuber is the so-called "tender bulb", which will not survive well in the ground temperature below freezing point.

Other tender bulbs (although some are technically bulbs or rhizomes) include calla, crocodiles, gladiolus and tubers. The tubers of these plants are unable to deal with temperature changes, and if left underground, they may become mushy and unable to survive.

Even so, don't rush to dig them out. Leave the tubers underground as long as possible at the end of the growing season, which will allow them enough time to cure well and store more energy for next year.

Here is a detailed guide on how to overwinter dahlias.

Step 1: Remove the top of Dahlia after the first frost.

As usual, in gardening, we use nature's time to arrange our work. So you should wait until the first frost, and then dig out your dahlia tubers.

The expert's advice goes even further. Even if you are experiencing a few minor frosts, you can leave the tuber underground because it continues to mature underground. At this point, you can buy yourself a few weeks until the first hard freeze kills all the leaves. Once this happens, it's time to dig out the tubers.

If you are planting several varieties of dahlia, now is the best time to label them. I know it's easy to think that you will only rely on your memory, but I guarantee that once you dig them out and dry them, it's not easy to distinguish tubers.

The best way to label a tuber is to attach one or more name labels to the stem. Later, you will transfer this label to a paper bag or cardboard storage box.

Then cut off the dead leaves, leaving about eight inches of stem attached to the tuber. Some people like to cut it lower, but I think it's easier to handle them with eight inches as a handle. If you choose to store them this way, it also makes them easier to hang and dry (more on that later).

After removing dead parts, you have two choices:

Option 1: Leave the tubers underground to force their "eyes".

What kind of terrorist programs are we talking about here? The eye of a tuber is a small protuberance that will become a bud. Next spring, these bean sprouts will grow into beautiful dahlia plants. The theory is that leaving tubers underground without leaves forces plants to start growing again. Let the eyes be clearly visible in autumn, making it easier to separate them at this time.

If this option is selected, always cover the exposed stems with aluminum foil or inverted yogurt cans to protect the hollow stems from rain. If you don't, they basically act as pipes, collecting rainwater and transmitting it to the core of the underground tuber. This can quickly lead to tuber rot and decay. About ten days to two weeks should be a long enough waiting time for eye development.

Option 2: Lift the tuber off the ground immediately after removing the leaves. This brings us to the next step.

Step 2: Lift the Dahlia tubers and arrange them.

Please note that I did not say "dig out" the tuber, because the digging should be minimal. Also do not pull out the tuber, otherwise you may damage any eyes that may have formed.

Instead, use a shovel to cut a square around the lump, and then use the same shovel as a lever to gently lift the tuber from the ground. You may encounter some root resistance. At this point, we can take root because their work this season has been completed.

If you lift them out of the dry soil, the tubers should be relatively clean. The dirt can be loosened and removed with a light brush. If you dig them out of wet, sticky soil, you should let them dry for a day before trying to clean them.

Step 3: Separate the Dahlia tubers.

Dividing tubers in autumn is a matter of personal preference. Some gardeners prefer to skip this step now and divide it in spring, just before they replant tubers for the new growing season. The advantage of waiting until spring is that the eyes of tubers are bigger and easier to find.

I prefer to divide my dahlias in autumn for two reasons. The main reason is to avoid the common "spring unbearable season" in gardening. I think I can spend time taking care of bulbs and tubers in autumn, because once the frost comes, there will be less gardening to do.

However, because most of my gardens are planted with seeds/bulbs/tubers, I am very busy with the beginning, pot planting, re pot planting, transplantation and reproduction of seeds in spring. Allocating my dahlia tubers in the fall is just one way to help me keep gardening chores going next year.

The second reason why I prefer autumn division is that it makes it easier for tubers to dry correctly before warehousing; They can also be stored more neatly and take up less space.

Here is how to divide the tubers of Dahlia.

First find the eyes on each tuber in the lump.

Always look for the top of the tuber, the eye stem growth area around the crown. The eyes do not grow along the body or around the root of the tuber, so this is the first clue that is easier to find them.

Use your fingers to feel small bumps under the surface. Sometimes, they are also visible. However, some tubers have no eyes, while others have multiple eyes. You want more of the latter. In some dahlia varieties, the eyes are more prominent than other varieties, so if you are not sure, you can wait until spring to separate them.

Cut the tubers from the main block, making sure that each tuber has at least one eye, preferably more. You can also divide the lumps into smaller groups and put the three tubers together.

Remember those famous brands you stuck on the stem? Ensure that the individual tubers are still in order at this stage.

It doesn't matter if the tuber is broken, as long as you have good taste. You just need to scab the broken tubers longer, and then you can store them.

At this point, you can discard any tubers that show signs of decay. You can try to save them by cutting off the rotting parts, but I find that the risk of rotting spreading to other healthy tubers is not worth this extra step.

You can get rid of the "mother tuber" - the central tuber that has produced all the young tubers throughout the season. Mother Tuber has done her duty, so it's time for her to rest in the compost heap. You can also get rid of any tuber without eyes, although I prefer to do so in spring, before I plant them, in case the eyes are too small to see with naked... eyes.

Can I skip the Dahlia tuber department altogether?

If this is your first time around the Dahlia merry go round, you may want to ask why you bothered to split the Dahlia tubers first. Can't we plant the dough as it is in spring?

You should never skip the step of splitting dahlia tubers, whether you are in spring or autumn. If you want exuberant, exuberant flowers, it is. If you put the tubers together, they will be too crowded and will compete for space in the spring. Think of it as a botanical version of sibling competition.

Therefore, even if you may germinate and eventually blossom, the stem will be slender and the flowers will not grow so big. And because tubers are already overcrowded, they will not breed in summer. Who doesn't want more free dahlias?

Step 4: Dry the Dahlia tubers and clean them again.

Now that you are ready to store individual tubers, it is time to clean them again. Gently brush away the remaining soil (if any) with a brush. Remove the feeder roots and the remaining stems. You can also wash the tubers with a hose, as long as you promise to have enough patience to let them dry properly before storage.

Then put them flat to dry or hang them in a cool and dry place to dry, with good airflow. The porch, pavilion and even the garage are good places to dry the tubers. When the skin is wrinkled, you will know that they are ready for storage, similar to the dried ginger root. For some people, it takes about five days, although in my humid climate, I found that tubers take at least ten days to heal properly.

Similarly, patience is a virtue. The better the dahlia tubers are treated, the more likely they are to be well stored in winter.

Step 5: Store Dahlia tubers.

Always store the tubers in a cool, dark and dry place.

The first thing to remember at this stage is to store the dahlia tubers at the right temperature - between 32 and 55 F (so above freezing, but below 13 C). Do not store them in rooms where the temperature is below freezing in winter. Similarly, if the storage area becomes too hot, the tubers will begin to sprout and develop prematurely to produce roots. Ideally, you want this to be as close to the planting time as possible.

The second thing to remember is humidity. You should store the tuber in a way that is not too dry, but this allows some water exchange between the storage container and the tuber itself. This means, for example, that just one cardboard box will cause the tuber to shrink, but a cardboard box full of newspaper lumps is a perfect choice.

Some of the things you can use as storage containers include plastic and wooden boxes, paper bags, cardboard boxes, baskets, and gunny bags. As a storage medium, look for wood chips, pet bedding, newspaper or butcher paper pieces or reuse some packaged peanuts. Some gardeners suggest using vermiculite, but I find that when I examine tubers, this option tends to stir up too much dust indoors. In general, I prefer to avoid using vermiculite alone - that is, not mixing in the potting medium.

This brings us to the last step (yes, there is one more).

Step 6: Check the Dahlia tubers once a month.

Ah, you think storing them is the last step, don't you? Not so fast. If you don't take the time to do a few quick checks during tuber storage, all your work will be in vain. You should check the tubers regularly - I try to do it once a month - to see how well they stay.

Remove and discard any tubers that show signs of mold, decay, disease, or any other type of damage. You can also discard the withered tubers (which feel hollow to the touch) and the tubers that have just become paper shells. They can't grow any bean sprouts.

If the rot is at the root end (not the crown end), some rotted tubers may be salvageable. You can cut off the rot, scab the cut, and then put the tuber back in the box with other tubers.

The wintering of dahlia tubers may sound like a complicated process, but I guarantee that this is not the case. Once you get the hang of it, it will become very fast. And I think the Dahlia you will get next year (and the money you saved by saving your own tubers) is definitely worth the effort.