The busy time of the Exhibition season is over. The blooms are available for all, with no cutting restrictions or rules; no special "don't touch that one" blooms. You've eased up on the heavy disbudding. Fantastic bounty. Then the rains begin . . . and stop . . . and the blooms return . . . and on . . . and on . . .and then the frost.
I find that I'm always quite ready for the end of the blooming season. It's not a sad time at all. Rather it's an exciting opportunity to see what the UNDER-GROUND HARVEST has produced. Those fabulous tubers that the Dahlia makes so freely. Well usually there is a good crop, but it is never certain! What will you find when you dig? What about that new, expensive one that bloomed so well? Will you be able to plant lots of it next year? There seems to be some mystery about digging and storing Dahlias, but it is very easy. This is what to do. . .
Cut off the top growth. Leave a few inches of stem exposed above ground to act as a handle and as a place to tie the variety label. Some folks move the stake label to the stem right away, even before digging. Remove the stake. The stem should not be full of water, nor hollow enough that water could fill it. If it is water filled, you must dig immediately and trim the stem back to solid tissue. Sometimes rot will have already produced those brown streaks that extend into the healthy white tissue of the tuber. This is a bad sign. If the variety is replaceable, give up and discard it on the spot. Benomyl CAN work, and I'll try it if I have to. Now I've gone and scared you! Well, unless you have brutally disbranched or cut extremely long stemmed blooms, you will not get this problem in normal cultivation, so relax.
The tubers are quite safe in the soil for a week or two as long as the ground does not freeze. Some people like to divide their garden tasks into stages and cut down and clean up at one time, and then dig a few days later(after a rest!). Many feel that the eyes plump up a bit and are easier to see. I don't like to leave them like that myself, so I dig in small sections of 10 or 15 clumps immediately after topping.
Use a spade or shovel, round or straight edge, but with a good strong handle. Do not use a garden fork. A fork won't cut the fine roots free and much more damage will be done. Insert the spade straight down about 9 inches out from the stalk and continue around in a circle. Then work the spade in and under and lever the whole mass up. [Photo] Not too much. If it is stuck, you will have to spade around again and cut all the feeder roots. When free, push down on the handle some more and if you are strong enough, lift the whole mass out of its hole and, while still on the shovel, bounce it gently once or twice to get rid of some dirt. If it is too heavy, most of the dirt can be removed with your fingers and judicious small shaking movements using the stalk as a handle - and then lift it. Clean away any easily removed soil and set aside. Dig another one. Etc . . . Don't forget to label them! This is where the crowd will split into different treatment techniques depending upon many very important personal differences.
Technique #1. Leave the dirt on. Let dry. It is very important to do the drying in a COOL area to prevent shrivelling. The dry soil will largely fall away. Trim the stem and all surplus & long, thin roots. If you have a root cellar or frost free, dirt floored shed, this will be sufficient - in fact it is ideal! Perhaps a covering of newspaper and/or a dusting of fungicide. This is Ferncliff Garden's technique (our major local specialist grower). Cutting the clump into separate tubers can be done at any time, however it is critically important to allow a COOL drying/healing/callusing time. Remember - the tuber is a living, growing thing. Give it a chance to heal.
Technique #2. Wash the dirt off. [Photo] Let dry. A cool drying period is so important. It is probably the one thing that most determines successful storage. Cutting the clump into individual tubers is best postponed for a few days to allow the development of a tough surface skin. Cool, but no frost of course. Then divide. Chemicals can be used at this point, but many are finding that nothing, or perhaps some Sulphur, is quite sufficient. I find it convenient to pass the cut tubers through a wettable sulphur bath because I want them wet anyway so that I can write their name on them with an Indelible Pencil. Let dry & heal for at least a few days. Once properly dried and cured and with healed cuts, the tubers can stand amazingly warm conditions without shrivelling. I have had tubers in a shed all summer that are still plump in August! The Dahlia survives its wild Mexican dry dormant season because of the WATER that it stores. Proper curing is the key. Give the natural survival mechanisms a chance.
Once you have divided, I recommend Vermiculite & plastic bags for convenient storage. I have tried SAND - too heavy! Peat Moss - too drying! Soil - too variable. The clear plastic vegetable bags at the supermarket are excellent and big enough to hold a typical divided clump. Add a 4 inch pot of dry vermiculite - the bag doesn't have to be full, but full is OK. The purpose is to create a micro environment of dry Mexican mountain soil. If spoilage does occur the vermiculite soaks up the released juices and largely prevents the spread of disease. Do take a look once in a while, through the clear plastic bag. Don't tie it, just fold over firmly. Wear a Filter Mask when working with vermiculite or pearlite. They are cheap insurance. Get some. I mark the bag with labelled masking tape and pack them into grape boxes. 18 boxes = 300 clumps and about 2000 tubers.
Some have tried coating with wax to help keep the tubers from drying out. The key element for safety is to use a double boiler. Easily made or bought at a second hand store. The wax never gets hotter than boiling water. Use a tongs of some sort. Tubers MUST be surface dry and cured is even better, so that subsequent shrinkage will not promote wax cracking.
Place the tuber into the hot wax and immediately pick it up with the tongs, hold to drip for a couple of seconds, place onto newspaper. Roll a variety up in newspaper cabbage rolls. Write on the outside. Keep as cool as possible - not freezing. Tubers treated this way are a bit more tolerant of warmer storage. Some claim slower starting in the Spring, but I dispute this. I have stopped doing it as my storage is cool enough not to need it. Waxed tubers are wonderfully clean to handle! Also, the occasional rotted one is somewhat contained by its shell, and neighbours are protected by theirs.
My storage is in an unheated basement room that also serves as a wine cellar.
During the whole digging/cutting season you should keep a note pad handy and jot down a few things.
You are bound to break or spoil a few, but never mind, everybody does! You'll have plenty.
If you only need a few for next year you can take a chance and leave them in the ground, with a really good layer of mulch, and dig and divide in the spring. Maybe you'll be lucky . . . lots of people are, but the better varieties are often the least tolerant of waterlogged conditions. And you will miss the excitement of seeing just what has grown under the ground. And then there is that 'Pot Root' idea, but that is another article. Good digging!
Copyright © 1996 Wayne Holland
email to nospam_hydahlia@shaw.ca just delete the nospam part!
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