Powdery mildew and pots

jacqueinthegorge(USDA 8 / Sunset 5)June 27, 2013

1) Some of my dahlias already have powdery mildew - we are having a long, cool, moist spring. I made up a baking soda solution and sprayed. Well, I overdid the application, and quite a few leaves have shriveled in protest. But on the bright side, the new growth coming in looks to be free of powdery mildew. In order to keep them that way, how often do I need to repeat the application? (more sparingly of course).

2) Gophers ate two of my dahlias planted in the ground. So I dug the rest up, and put them back into large pots. Interestingly, the root balls were smaller after 3 weeks in the ground than they were when I took them out of the pots - I suspect due to the aforementioned long, cool, moist spring, the ground was a bit too cold to be welcoming. But soon, the soil in the pots will get too hot, and I know they don't like that. I wonder, has anyone here experimented with partially burying the pots in the ground? How did that work for you? Any other solutions to the gopher issue?

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Jacque, I am anticipating mildew mold this season because I planted way too close this year, and because some plants I got at auction had some already on their leaves.

I immediately took those leaves off, and will be stripping all leaves from about a foot down once the plants achieve three feet height. This allows ventilation through the plants, drying the leaves from rain and morning dew to discourage mildew.

I've not heard of the baking soda solution, but many people swear by using milk. Here's a recipe I recently copied from a dahlia discussion:

Mildew- Mix 1/3 cup milk with 2/3 cup water and spray on the leaves. Whole milk, not skim.

As for planting pots in the ground, there are some growers that do that all the time. It allows the ground moisture to keep the pot soil from drying as quickly, and protects from underground attacks. Perhaps someone else can go more in depth about growing in sunk pots, as I haven't tried it.

As for gophers... Elmer Fudd is the best solution I've found, fighting with a rabbit population that decimated the new growth of a dozen plants each day. Three types of deterrents have not worked, and I'm not fencing at this late date. Some tender-hearted souls advocate catch and release. One gopher for a taste of dahlia can do a lot more damage then my bunnies in a day... Imagine a family of them moving into your garden.

    Bookmark   July 1, 2013 at 11:51AM
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jacqueinthegorge(USDA 8 / Sunset 5)

Thanks CCvacation, I will try the milk spray. Seems like it would not be as damaging to the leaves.

Oh the gophers are terrible on dahlias here. We gas the tunnels, and it keeps the population down, but all it takes is one...

Another thing I may try is planting a trap crop for the gophers. Jerusalem artichokes are a lot cheaper to replace than a named dahlia, and I imagine the tubers are very similar in food value to a rodent.

I'll let you know how plunging the pots works. Because it's so windy here, the tallest dahlias I grow are 3 feet. I have some 10 and 15 gallon pots I can put them in, so maybe that will work. Between the heat and the damage from the baking soda, some of my dahlias look really sad! and many of the others are showing the beginnings of mildew. Crossing my fingers...

    Bookmark   July 2, 2013 at 8:40PM
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jacqueinthegorge(USDA 8 / Sunset 5)

The soil in the sunk pots is definitely cooler. But I think that even my shorter-statured dahlias would be happier in 10-gallon containers. I know at least some of the fabric pots are meant to be in the ground, but I'm wondering how they hold up when attacked by gopher teeth. Anyone have any experience? I've also thought about drilling lots of holes in my containers to give the feeder roots more running room, while keeping the tubers safe. I'd think the heavier duty injection-molded containers would be somewhat resistant to gopher teeth, I'd appreciate some opinions.

    Bookmark   July 17, 2013 at 9:01PM
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