FAQ: Dahlia Basics

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Table of contents
» What kind of plant are dahlias?
» Are dahlias perennial or annual?
» 'Dinnerplate' or 'Mammoth' Dahlias?
» Where can I go to buy new dahlias?
» Sellers: Distributors versus Growers
» How do you grow dahlias?
» How can I keep my dahlias for next year?
» Does the size of the tuber determine the size of the plant?
» What are those codes next to a variety name?
» Can I Grow Dahlias From Seed?
» How do I start my dahlia tubers/seeds inside before planting time?
» Where can I ask questions about dahlias?
» I want to learn more! How do I find information in this group?
» Difference between roots from the bottom of the tuber versus bottom of the shoot

What kind of plant are dahlias?
Dahlia (UK /deɪliə/ or US /dɑːliə/)[4] is a genus of bushy, tuberous, herbaceous perennial plants native to Mexico. A member of the Asteraceae (or Compositae), dicotyledonous plants, related species include the sunflower, daisy, chrysanthemum, and zinnia.

The stems are leafy, ranging in height from as low as 12 in (30 cm) to more than 6–8 ft (1.8–2.4 m). The majority of species do not produce scented flowers or cultivars. Like most plants that do not attract pollinating insects through scent, they are brightly colored, displaying most hues, with the exception of blue.

Flower forms are variable, with one head per stem; these can be as small as 2 in (5.1 cm) diameter or up to 1 ft (30 cm) ("dinner plate").

The dahlia was declared the national flower of Mexico in 1963.The tubers were grown as a food crop by the Aztecs, but this use largely died out after the Spanish Conquest. Attempts to introduce the tubers as a food crop in Europe were unsuccessful.

There are 42 species of dahlia, with hybrids commonly grown as garden plants.

A great variety of forms result from dahlias being octoploids—that is, they have eight sets of homologous chromosomes, whereas most plants have only two. In addition, dahlias also contain many transposons—genetic pieces that move from place to place upon an allele—which contributes to their manifesting such great diversity.

-text borrowed from Wikipedia

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Are dahlias perennial or annual?
Dahlias are what growers in the Northern Hemisphere call 'tender perennials.' They will come back the following year if the tubers do not rot and do not freeze.

Depending on your zone and soil conditions, dahlia tubers might survive a winter left in the ground. Many growers choose to dig their tuber clumps and store inside after frost kills the top of the plants. Others treat their dahlias as annuals, leaving them in the ground to survive or die, and simply planting more in the early summer to take any lost dahlias.

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'Dinnerplate' or 'Mammoth' Dahlias?
For mass marketers in the gardening business, the phrases 'Dinnerplate Dahlias' or 'Mammoth Dahlias' bring in big platters of money as casual gardeners imagine 11 or 12 inch blooms growing in their garden (after all, my dinner plates are eleven inches...) and spend money for a random mix of dahlia varieties that often average 4-6 inches with the best of care and experience. By the time the dahlias bloom, the casual gardener forgets the sales gimmick with the fantasy of huge blooms, and starts enjoying the real thing.

There are varieties that grow extra large 'dinner plate' size, which we call A and AA's, but without proper cultivation practices, even those varieties will be significantly smaller then their potential. Here is a chart that explains the different sizes of dahlias... http://cubits.org/Dahlias/thread/view_post/1180195/

Cultivation practices are extremely important, if you want to grow your dahlias to their full potential. Check out this article for advice about how to get on the right track...
Or check out the Growing Season FAQ here: http://cubits.org/Dahlias/faqs/view/growingseasonquestio/

I hope this starts you out on a great adventure with dahlias, and you join our ongoing conversations soon.

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Where can I go to buy new dahlias?
Normally you can pre-purchase dahlia tubers or plants between November through May, with shipping dates from March through May.

Members of this group have links to their storefronts here:

There are currently (as of 2016) two 'Big Lists' of dahlia suppliers and dahlia varieties out there:

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Sellers: Distributors versus Growers
There are two types of dahlia sellers: distributors and growers.

The DISTRIBUTORS simply resell a product that they buy from another distributer or buy directly from growers. From necessity, the distributers must buy in bulk in order to make a decent profit. Most bulk sales in dahlias come from Holland, and many serious growers moan on a regular basis on how bad the average of success is with the correct variety type. The distributers simply don't care, as even the collection names are rarely accurate, and they know that casual growers probably won't care once they see any type of color, anyways. Terms such as 'dinnerplate' and 'pompon' are mostly meaningless, as they are simply words that have been proven to sell product. Normally, they will give you credit for another product if you complain.

The GROWERS sell tubers they have grown. Typically it's one or two people doing all the digging, labeling, storing and fulfilling orders, with less than a dozen growers I know about that have seasonal employees outside their immediate family. In the U.S., you are sold individual tubers that resemble chicken legs instead of the dusty often-broken mini-clump that the distributers sell from Holland. This is because the growers divide up field clumps from plants for resale instead of mass-producing cuttings in small spaces to sell like the Holland growers. As a result, there is much more variety offered by growers that sell. Although there are still mistakes made in labeling, (we are human, after all) there is accountability as you can normally contact the person who made the error and they will make it right (all the way back to making sure that variety is correctly marked the following year in their beds). Growers typically use correct terms for the varieties they grow, as many of them are show people and take great pride in their product.

Although a buyer can expect to spend a bit more on purchasing from a grower directly, the likelyhood of being happy about the outcome is higher. Nothing is wrong with buying from a distributer, but it helps to know that they are marketing to casual growers who typically don't care about the end result so long as it's pretty. Just adjust your expectations with the lower price point.

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How do you grow dahlias?
A simple answer to that question is this:
-plant out after the danger of frost is over
-plant down about four inches
-support the plants with stakes or cages
-water and fertilize often
-cut blooms and deadhead frequently to encourage more blooms

The best place to find in-depth answers to that question is in the Growing Season FAQ, found here:

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How can I keep my dahlias for next year?
You can either prepare the beds for winter and hope they make it,
You can dig the tuber clumps to store inside and hope they make it.

There is a learning curve in overwintering dahlias, but it is very possible to do well and keep collections intact over multiple winters.

Read detailed questions and answers about overwintering dahlias here:

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Does the size of the tuber determine the size of the plant?
The simple answer is, 'no.' However, there are two important points to keep in mind to qualify this simplistic answer...

#1. GROWTH DEVELOPMENT: Dahlia tubers consist of starch in the body, with meristem tissue (called eyes) on the 'head' of the tuber. From the eye comes the sprout, from the tuber comes the energy for that sprout. A sprout can live without the tuber starch after it has grown enough (average is 3 inches) to put out roots of its own, so tuber size does not limit plant size once feeder roots are established.

#2. NEXT SEASON'S TUBERS: Most serious growers that I know actually prefer the smaller tubers, about the size of a roll of quarters, with necks no thinner then a pencil. They avoid the fat baker potato sized tubers, saying that those tend not to make many tubers for the following season. However, plant size is the same regardless of tuber size because plants develop from the meristem tissue, not the body of the tuber (starch depository).

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What are those codes next to a variety name?
There are so many different shapes and color combinations of dahlias that most new growers are absolutely amazed at the diversity in this species.

And those who are avid dahlia growers have a system for keeping all those forms, sizes and colors straight. Check out the code chart here: http://cubits.org/Dahlias/thread/view_post/1180195/

Here is a fun article that explains how the dahlia community keeps track of all the forms, sizes and colors here...

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Can I Grow Dahlias From Seed?
Dahlias can be grown from seed, but they will not necessarily look like the parent plant. This is how new varieties are born. To reproduce a particular variety of dahlia, the new plant must be grown from a piece of the original plant, such as a tuber or cutting. Just as children of the same parents look different from their parents and from each other, seedlings will usually have some resemblance, but can look very different. They inherit some characteristics from each parent, in different combinations.

Dahlias are genetically even more variable than humans. Like most organisms, we have two sets of chromosomes ("diploid"), one set from each parent. Dahlias have eight sets of chromosomes (they are "octoploid") so there are many more possible combinations of genes, and differences are often a matter of degree, not just either/or characteristics. It is true that smaller flowers are more common than large flowers, and open centers are more common than fully double centers. The dahlia seeds available in packets are almost all bred to produce the small bedding-type dahlias

Breeding dahlias to get certain characteristics is what hybridizing is all about.
– see the FAQ on Hybridizing Basics

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How do I start my dahlia tubers/seeds inside before planting time?
Many experienced growers pre-start their tubers and seeds inside so there are both leaves and roots before setting them in the ground, giving the plant a head start in the season. Other growers, experienced and otherwise, don't bother with pre-starting.

Read detailed questions and answers about pre-starting dahlias here:

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Where can I ask questions about dahlias?
We have an active membership in this group that would love to help or point you in the right direction. However, you must belong to a Cubit group or this group to write comments or ask questions. Click here to join: http://cubits.org/dahlias/join/on/?submit=Join this cubit!

Once you are a member, please feel free to speak up and ask anything dahlia-related in the 'Reply' box at this link:

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I want to learn more! How do I find information in this group?

Look on the TOP right hand side of your screen. There are links that take you to different areas on this forum, and you should really check them out!

The most important four:

1. Articles- this gives you an overview of the care dahlias require, and explains the codes that tell growers what type of variety they are growing. Well worth the time to read!

2. FAQ (frequently asked questions)- the best place for a quick answer on growing dahlias. A great place to learn the basics, and ask for more information. Most questions are answered within the same day.

3. Database- there is a variety archive that has images and descriptions of many popular types of dahlias. You may search for a specific variety, or add one that we haven't documented yet!

4. Forums- careful- you can get lost for DAYS in there! The forums group different discussion threads together according to topic, and go back for years. It's amazing what gems of wisdom or silly chit-chat you can uncover... Feel free to join in on the discussions! If you have a question after reading older threads, you can re activate them by adding a comment at the bottom of the thread. Or, to be part of what's being talked about currently, lurk on the 'recent threads' section on the main page, and jump in when you wish.

Want to join in on the conversations but not sure where to start? Join the group, then click here to introduce yourself!

Once you get more comfortable with the Cubit layout, this all will be second nature for you! Again, welcome to our 'Growing Dahlias' community, and we hope to talk dahlias with you soon!

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Difference between roots from the bottom of the tuber versus bottom of the shoot
The roots from the bottom of the tubers are to get the plant started. There is food and water in the tuber to feed the shoots at first. When the tuber grows roots it is able to shuttle water & minerals from outside up to the new growth. Eventually the plant gets big enough to start needing more, and grows its own roots from the base of the shoot. Those are the ones that will support the plant for the rest of the season, and make new tubers. If the mother tuber is very big, the shoots don't have to go looking for food, so they don't make as many roots of their own, and you get fewer tubers at the end of the season.

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Other FAQ pages that may help you:
» Help! I'm new here... What do I do?
Learn the best places to check out first on this forum!

» Pre-Season Questions

Quick answers on how to pre-start tubers, take cuttings, starting from seed, etc.

» Growing Season Questions

Quick answers on planting, watering, dealing with pests, topping and disbudding.

» Post-Season Questions

Quick answers on digging, dividing and storing dahlia tubers

» Hybridizing Dahlias- Basics

Currently open to Cubit Members & Active Members.

» Hybridizing Dahlias- Advanced

Growing Dahlias:

A place to learn about dahlias, and a vibrant community of dahlia growers to ask, share and enjoy.

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The Discussion Dahlia

'Unrecognized Form' Dahlias
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