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Re: Observation

CCREDUX@aol.com wrote:
How do you protect the plants in the winter? I have overwintered containered hostas with only mixed success. Method used was to lie pots at about a 45 degree angle with the ground (patio) and cover with hay or straw. What is the best method? Do you or does anyone else put the pots in an unheated shed (garage)?
Many thanks,
Clyde Crockett z5 Indy (brrrrrrrrr) IN
We probably winter about 40,000 hostas outside in containers.  We also winter some varieties in unheated cold frames, but those are generally the ones that come up very early in the spring, plantaginea and montana types and such, and the protection is from late spring frosts and freezes, not winter temps.  Our cold frames stay a bit cooler in the spring and the plants stay dormant a bit longer.  While we always have losses due to one thing or another, in the great scheme of things, our percentage of losses is very close to zero - knock on wood.

We winter our pots under microfoam and white plastic.  Microfoam is similar to styrofoam, but it is flexible and it comes in 6'x300' rolls.  The purpose of the microfoam is to keep temperatures from fluctuating rapidly, not to keep the plants warmer. Microfoam is probably not practical for the homeowner because I don't think it is available in small pieces, but you can use other things that will serve the same purpose. Plastic goes on top to keep any water from getting into the plants while they are covered.  In our area, we cover sometime in December, depending on the weather, and uncover around the end of February.  When to uncover is always a question, because the plants under the covers will break dormancy earlier, so we want to wait as long as possible to uncover, but make sure we do it before they come up. Sometimes we have to recover if we get a cold spell.  Bait for the mousies is also necessary under the covers.

The main problem for the plants over winter is water, not cold.  They should be moist, but not wet, when covered, and as long as they are covered with plastic, they should not need any additional water until spring.  I suspect the biggest reasons for losses are the soil mix people tend to use and the size of the containers.  Drainage is all important.  If you look at the mix that most growers use for hostas, you will see that it is usually made of bark or some other very chunky material, not soil or peat.  Unfortunately, because most people don't like to pay much for potting soil, most retail mixes are not very good. If you use peat or soil based mixes, which hold a lot of water, you have to be much more careful to make sure the plants don't have too much water.  I always suggest using the smallest container possible.  If you are going to give the plant room to grow, do it in the spring, when the plant is in active growth.  If you put a plant in a pot that is larger than its roots can occupy before dormancy, it is probably going to hold too much water and crown rot is likely.  For the same reason, we do not like to divide or pot plants after August so the roots have a while to grow into the pot before winter.  Also, resist the temptation to water the plants when you uncover.  Until they start to grow leaves and the weather warms up, water will do more harm than good.   Water only enough to keep them from drying out completely, if the pots are damp, that's all they need until they start producing leaves.

Since the main cause of losses is crown rot, we are considering using ZeroTol as a drench to see if it makes any difference.  Since ZeroTol is essentially very strong peroxide and is effective on both fungi and bacteria, it might be worth while to experiment to see if a peroxide drench, maybe 10 oz of peroxide in a gallon of water, would be helpful.  Since ZeroTol is also apparently effective on nematodes, I would think peroxide drenching would be a good idea as long as we determine that it does no damage.  I doubt that it can do any harm, but I don't make any guarantees and I suggest you try it on your undulatas before you drench your Dorothy Benedict.


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