5 Steps To Divide Dahlia Tubers (2024)

FAQs

When should you divide dahlia tubers? ›

When to Lift and Divide. Tubers will continue to take up and store nutrients until it becomes too cold and they go dormant. The American Dahlia Society recommends lifting the tubers every year, either 120 days after planting, or in cooler climates, after the first frost that's cold enough to kill the foliage.

Do You Soak Dahlia Tubers Before Planting? Generally, dahlia tubers do not need to soak before planting. However, if they appear dried out and shriveled, you may want to soak them in a bucket of tepid water for one hour before planting.

Rinse Dahlia Tubers

Make sure not to puncture the skin of your tubers, as this could cause them to rot over the winter months in storage. Gently rinse excess dirt off of the tubers with a garden hose or in a tub of water.

Though the foliage may be dead, dahlia tubers will continue to develop for a time. Delay cutting dahlia stems until right before digging, because the stems are hollow and can collect water, which in turn promotes crown rot and tuber decay.

Dahlias will die if hit by a long frost, so it is wise to dig them up at the end of the summer and overwinter the tubers indoors. This is an ideal time for splitting dahlia tubers. In spring, plant each healthy one for even more of these lovelies. Dahlias can be propagated through seed, cuttings, and root division.

After a hard frost, when the dahlia foliage and stalks die back, cut the plant back to about 6 inches from the ground. Some growers prefer not to cut them back because the stems are hollow and cut stems can fill with water and potentially cause the tubers to rot.

Each plant will produce a clump of new tubers which, undivided, will produce smaller plants with poorer quality blooms. Eventually the plant will become so congested and the results so poor that it should be lifted and divided.

As long as you plant a clump or tuber that has at least one eye, it will grow into a plant.

Pack the tubers

You can also store dahlia tubers in vermiculite, or wrap them in dry newspaper. Once packed into their pots, store your tubers in a frost-free place, such as under the greenhouse staging, in a dry shed or garage.

When planting dahlias, it is important to allow them enough space to grow. Some varieties can become quite large and planting too close can cause plants to not receive enough light or air flow which can lead to mildew issues later.

Can you plant dahlias 12 inches apart? ›

Dig holes for planting.

Most Dahlias are spaced with approximately one tuber per square foot. The largest varieties of Dinner Plate Dahlias will do best with wider spacing, about 12-18 inches apart, to allow for foliage and flowers to grow. Compact varieties can be planted with multiple tubers per square foot.

Dahlias get quite large, so allow at least 12 to 18 inches (30 to 46 cm) of space between plants.

As you get towards spring and are ready to start planning your garden or farm season, we recommend pulling your tubers out of storage and waking them up by bringing them into a warmer environment with temperatures in the 60s two weeks before planting.

Dahlias love to be in the dirt. The dirt is a friend to Dahlia Tubers. They prefer loosened and well drained soil. If you have clay or thick/heavy soil, loosen it well, and you can add sand or peat to help with drainage.

Dahlia tubers should be planted 10cm deep in fertile well-drained soil, outdoors in spring when the frost has disappeared. They prefer to be in a sunny location and spaced at approximately 45cm apart. In areas where there is extreme cold, dig up dahlias and store in a cool peat over the winter.

In short, when you are looking at dahlias that seem dried out, it does not mean they will not be viable. You can tell by the feel of the tuber if there is still moisture inside and as long as they are not dried out, they will be fine.

Waking up your tubers 10 to 12 weeks before your region's average last-frost date will help ensure that you have healthy plants—not too leggy or root-bound—ready to set out in the garden in early summer.

Next, there must be the right amount of moisture in the storage medium. Too much water will encourage rotting of the tubers. On the other hand, if the medium is too dry, the tubers will begin to shrivel, and if enough moisture is lost, they'll die.

Store in a well-ventilated, frost-free space: 40º to 45ºF is ideal, 35º to 50ºF is acceptable. Check on the dahlia tubers occasionally over the winter. Remove any tubers that have started to rot before the decay spreads to healthy tubers.

Cut away feeder roots and the bottoms of the tubers.

Neither the roots nor the tuber tips are required to regrow the dahlia in the spring. If you can obviously see the 'eyes' of the tubers, which look like little pink bumps, you can cut back the stalk and crown even further, so long as you don't remove the eyes.

Can I store dahlia tubers in sawdust? ›

If you can't bring yourself to wrap the tubers in plastic, store them in a loose, barely moist, non-soil medium, such as peat moss, sawdust, sand, or vermiculite.

What month do you cut back dahlias? Cut back dahlias in late fall – October and November, however don't cut them back immediately. 'Leave the stems to go black from the first frost for approximately a two weeks to allow the sugars to go back down the stems to feed the tuber.

The key to successfully storing dahlia tubers for the winter is making sure they stay dry, have good air circulation and are in a cool, dark spot. You can store the tubers in a variety of containers – milk crates, plastic bins, paper bags, and cardboard boxes all do the trick. You may choose to pack them in peat moss.

A dahlia that's pinched produces twice as many branches from each leaf node. This gives you a stronger, bushier dahlia with more flower stems. Though pinching slows growth for about 2 weeks, the plants quickly catch up. Dahlias can also get leggy if they are not receiving enough light.

Dahlias are vigorous plants and the stems can become overcrowded. You may wish to thin them out in June/July to improve the overall display: Aim to keep seven to ten sturdy stems per plant.

It's also a good idea to divide dahlias every year because of how quickly the tubers grow. If they get too large, they will rot or become too heavy to lift and store.

If you take cuttings in early spring as sprouts burst to life, you may get five, 10, or even more plants from one tuber.

Similar to a potato, the tuber sends up a shoot that becomes the plant, which produces leaves and flowers. Underground, the tubers multiply each year (again, like a potato). You only need one tuber with one "eye" to successfully grow a vigorous dahlia plant.

The size of the tuber is irrelevant in most cases. We grow some varieties of dahlias that never produce tubers larger than our pinky, while some produce HUGE tubers that we have to cut down to size. It all depends on the variety of dahlia.

The first application of fertilizer for your dahlias should be about 30 after planting and repeated every 3-4 weeks throughout the season. Follow the manufacturer's directions on the application amount. One of the biggest mistakes with dahlias is overfeeding them with high nitrogen fertilizer.

Can you store dahlia tubers in kitty litter? ›

Towards the end of the year (October or November), dig up the tubers and store them just as you would potatoes -- a cool, dark, dry place with air flow is best. Separate the tubers. Then wrap them in paper towel, place in sawdust or kitty litter, or hang in discarded stockings.

After cutting, dipping, and marking the tubers, let them dry. Expect to let the tubers dry for about 24 hours for small roots and 24 to 36 hours for medium to large roots.

I like to divide my dahlias before storing them, but you can also wait to divide them in the spring. My dahlia tubers are stored in plastic containers with vermiculite. You can also store your dahlias in peat moss. Don't store your dahlias in cardboard boxes as the cardboard will suck the moisture out of your tubers.

You only need one tuber with one "eye" to successfully grow a vigorous dahlia plant.

planting dahlia tubers in the ground

If you don't have space to plant the tubers in pots first, you can put them straight into the ground in spring – just make sure the frosts are nearly over. Plant the tubers just under the soil surface and ensure they are approximately 75cm (30in) apart, depending on variety.

Dig holes for planting.

Most Dahlias are spaced with approximately one tuber per square foot. The largest varieties of Dinner Plate Dahlias will do best with wider spacing, about 12-18 inches apart, to allow for foliage and flowers to grow.

How many dahlia plants can I get from a tuber? One tuber = one dahlia plant = many blooms per plant. The number of blooms per plant varies, depending on the variety (the smaller the bloom, the more you tend to get per plant). Some people will take cuttings from their dahlia tubers (do so at your own risk).

In short, when you are looking at dahlias that seem dried out, it does not mean they will not be viable. You can tell by the feel of the tuber if there is still moisture inside and as long as they are not dried out, they will be fine.

Dahlias do not like mulch or store-bought garden soil, as many of these products can possibly harm the tubers. Once soil is loosened and dry and about 12-15 C (55-60F) you are ready to plant!

Bulbs should be planted pointy-side up, but if you placed them upside down don't worry. Bulbs know “which way is up” and they will turn themselves around.

What happens if you don't Deadhead dahlias? ›

It may be feeling distinctly autumnal right now, but if you've planted dahlias the good news is they will keep on flowering right through to the first frosts. There's just one catch: to prolong flowering you will need to keep deadheading them, thereby encouraging the plant to produce new buds.

Dahlia tubers should be planted 10cm deep in fertile well-drained soil, outdoors in spring when the frost has disappeared. They prefer to be in a sunny location and spaced at approximately 45cm apart. In areas where there is extreme cold, dig up dahlias and store in a cool peat over the winter.

The tubers should be planted in full sun and well-drained soil with lots of organic matter after the risk of frost is over. Make sure you do not over water dahlias after they are planted. They need very little water until the plants are at least 6”-12” tall.