DAHLIA TIPS for the FALL

Dahlias can be the most beautiful in the fall. They’ll continue to bloom until the first killing frost. There are Dahlia Shows all across the country in September. It is a great place to see  wonderful, inspiring, award-winning flowers. The Rochester Dahlia Society has one every September. 
 
Stop fertilizing your Dahlias by late August to encourage tubers to store nutrients for survival over the winter.
 
Rochester’s Zones  6a and 6b are not mild enough to leave tubers in the ground over winter. Most will not survive in the harsh conditions here. Tubers must be dug up and stored. This is a careful, meticulous process and every Dahlia grower has their preferred methods. If you’ve found a good method that works well for you, then that is the best method.
 
When to Dig?
This used to be easier to determine. A killing frost freezes and kills every Dahlia stalk. It was obvious then that it was time to dig. Now a killing frost often does not occur until late November or there is only a partial frost. Tubers can rot if left in wet ground too long. Pick a time to dig when conditions are best to do so. It should still be warm enough to be comfortable digging and using a hose to wash tubers.
 
Dig tubers up between late October and the second week of November. As long as tubers have been in the ground 120 days they can be taken up.  
 
The first step is to cut off the stalks leaving 2-3 inches. Then allow 1-2 weeks for the tubers to harden. Whether it is 1 or 2 weeks is also dictated by weather. Some growers protect the cut end of the stalk with foil or other material, but many find this is not necessary.

Digging                    
Using a shovel cut around the stalk in a circle 12-18 inches in diameter. You must allow enough room, so the tubers or roots do not get cut. A tuber with a cut neck will not grow. Carefully dig up, lift, and remove the tuber clump using a pitchfork or shovel.  
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WATCH OUT FOR LABELS!
From the moment tubers come out of the ground, be constantly vigilant that their labels stay with the clump. Most of us in the Rochester Dahlia Society have a label tied to the tuber, one in the ground and one on the stake. Yet every year we inevitably end up with a tuber or two that loses a label. These are now a “Mystery tuber” or as we call them, No Id or Noids.
 
Wash
Place your tubers in a basket or container that allows you to wash them and lets the dirt and water flow through. Some use laundry baskets. I use a metal mesh compost riddler set on top of a wheelbarrow. Wash tubers gently but thoroughly with the spray nozzle on low.  Be careful not to break any tuber necks. Allow the tubers to dry. This is a step where labels can easily get separated from their tuber.

​Trim and Dip                                
Keep your clumps and tubers on tables or another elevated work surface. Don’t put them on a concrete floor which can fatally chill them. They also won’t dry as fast. If you have old towels those can be used on the tables.  While drying, don’t leave tubers outside overnight or in a garage. If the temperature goes below 35 degrees, it can kill them.
 
Most of your clumps will be large and each tuber is full of feeder roots that have grown outward to get food for the plant. Trim off all the feeder roots with pruners or garden scissors. You can also cut off any small skinny necked tubers in the clump or tubers attached to another tuber.  These won’t grow. Remove the large “mother” tuber. This is the original tuber that produced the plant. It is big and old looking and is usually a different color. This tuber will usually not produce a plant again and rot.
 
Before storage, the tubers must be left alone to dry thoroughly. This can take 2-5 days. Any cuts in the tuber from trimming must heal for 24-48 hours.
 
Some growers dip their tubers or clumps in a 10% Borax solution or 10% Clorox solution to fight fungus. Others treat their tubers with powdered Sulphur, Cinnamon, or another other type of fungicide. Some growers do not treat for fungus and have not had a problem. Making sure the tubers are dry is the key to successfully storing them. And watch out for those labels!

​D-I-V-I-D-E
You can do it! Many growers divide their tubers in the fall. It makes them easier to store and quick to pot in the spring, but it is harder to see that critical EYE. Every tuber MUST have an eye, or it will not grow. Eyes are found at the top of the tuber where it joins the stem. To be viable a tuber must have an eye and part of the stem. 

​Those who prefer to divide in the spring cut the big clumps into more manageable smaller clumps of whole tubers.  The eyes are easier to see in spring, and many will start to sprout. It’s so exciting to take a tuber out of its bag and see a sprout already started.
 
Whenever you decide to divide,  you’ll need shears, scissors, knives, and a favorite tool of the RDS- a PVC pipe cutter. Some tubers are hard to cut! It is suggested to clean all cutting tools after dividing a clump of tubers. This will reduce the risk of spreading disease from one clump to another.
 
If you need help, there are a lot of resources available. The RDS does dividing demonstrations every Fall and individual help is available, too. Contact www.RochesterDahlias.org. Another good source with instructions and pictures is  www.Coloradodahlias.net. Click on Dahlia Culture.
 
 
Pack and Store
Your now dry clumps or single tubers must be packed up and put in some type of storage medium- with their labels of course. They can be put into plastic bags, plastic boxes, or tubs, or some use Styrofoam grape boxes. The tubers are then covered with medium. Storage mediums include peat moss, a peat moss/ vermiculite mixture, vermiculite alone, wood shavings, sawdust, or even potting soil. A new method some have tried and like, is to wrap a bunch of individual tubers in plastic wrap clumps usually by variety. They are then stored in a refrigerator.
 
Your bags of tubers should be placed in a box or tub to protect them from light during their winter sleep. Mold, rot, and shriveling are the things to look out for which can destroy Dahlias in storage. Check your tubers each month over the winter. If you see rot or a tuber is mushy, discard it immediately. It will infect the whole bag. If some are moldy spray them with Lysol and wipe. If shriveled spritz them with water. Tubers need to be moist but not too moist and dry but not too dry. But don’t despair. For the most part they are very hardy and survive winter storage well.
 
In late February bring the boxes out of the dark, open the containers and bags inside at room temperature and keep them in light to “wake” them up. Keep them like this until time to pot each tuber in early April. Be sure to check for mold or shriveling during this step, too.
 
From fall digging, to storage can take several weeks. This is especially true for those with hundreds of tubers to take care of. But once inside out of the elements you can take your time to do it.
 
The storage temperature for Dahlias should ideally be around 45 degrees F. A range of 35-50 degrees F is suggested. They should be kept in the dark.
 
Digging washing and storage is a labor of love. As we put them away, we are already thinking of new tubers to try next year. Is it worth it? YES! That first spring bloom makes it all worthwhile.