Sun or shade?

I'm getting ready to put in my new dahlia bed. I have a question. Everything I've read says full sun is best but some shade is okay. One site said if you lived in a hot and dry climate, part shade was best.

The summers here, July and August in particular, are very hot and usually very dry. In addition, my soil is very, very rocky. Even in areas where I've improved the soil or put in a raised bed with new soil, the biggest problem is keeping everything from being dry as a bone during those months.

So should I put the bed in full sun or in an area where it gets some shade?

I think partial shade is perfect for your area.
Christine

hart, if you have a problem with hot dry summers, do you mulch your beds to conserve moisture? I find it a necessity. Of course not before the sprouts come up, because they need the heat to come up.

Yes I mulch, but I basically live on a pile of rocks with some strips of better soil here and there. It can rain or I can water deeply and a day or two later, depending on how hot it is, that soil is dry as a bone again because the water just drains down.

It's nice and lush here in the spring when we get plenty of rain but it's not usual go to for weeks without rain in July and August.

This is part of my front yard last May. See all that nice green grass? By July, the grass will be gone and nothing left but extremely drought tolerant weeds like prickly pear and pussytoes.

Well, I think I've found the perfect spot. It has much better soil than the rest of the yard, although I have lots of compost to work in there too. It gets shade in the late afternoon but sun the rest of the day and even later towards evening.

Thanks everyone for your help. Tod, how warm should the soil be for planting? I have a soil thermometer so I can make sure it's just right.

I read that it's best to have a minimum of 55 degrees soil temp at night. I think weather-wise it should be at least 45 degrees, I think I heard, I try to stick to that. More heat = faster sprouting.

70F for planting out. I dig the holes in advance and let the sun warm the soil up. What's your zone hart? What's you high temps in the summer? Inquiring minds need to know all the details LOL ^_^

I'm in zone 6. It's colder here in the mountains than in the rest of Virginia. Highest temperatures in the summer can be over 100 but 90s is more typical and it gets much cooler at night. Most of our really hot weather is in July and August.

We get a lot of temperature swings in the spring. It was cold enough for me to be running the pellet stove the other day but yesterday and today were in the 90s. Our last frost date is supposed to be April 15 but it sure isn't. Usually it's mid to late May.

Hart you're talkin to a Rocky Mountain girl. Cold nights are my life. You are in a perfect climate for dahlias. They are native to the mountains of Mexico. I wouldn't worry about sun/shade if I were you. Grow them where you want. I would plant them out after you know your last frost date for sure.

That's very good to know. I am worried about being able to keep them moist enough in the hot part of the summer, though. Thanks again, Tod and Dahlianut.

I think our mountains are probably bumps in the road compared to the Rockys, Dahlianut. LOL That's part of Massanutten Mountain in the distance in the photo above. Beyond that we have the Alleghanies and the Blue Ridge on the opposite side behind me.

I start mine peat moss which helps hold moisture. We've been in drought and I try to be waterwise.

I have lots of peat moss. I also have a lot of nicely aged rabbit manure. I think that might help if I worked it in with the compost. Do you start yours in pots and then plant them out? I could do that if they need to be planted right away.

The spot I'm thinking about for the new bed does hold moisture a lot better than, say, the front yard. Make that a LOT better. LOL

hart I woke mine up awhile ago and they are growing in the greenhouse. I have such a short growing season I like to be an early bird. LOL re the "mountains" definition. Sometimes when I see "mountains" in other places I think O those are drumlins. It's all relative and our different perspectives make life grand, dontcha think?

I think our mountains are just the right size. LOL My sister lives down in southwest Virginia where the same mountains are much higher than here. It's a little too bumpy down there for me.

Massanutten is a lot smaller than the Blue Ridge or Alleghanies, though. If the angle was right and you could see the Alleghanies behind Massanutten, they dwarf little old Massanutten. It looks pretty far away in that photo too but it's only about a mile and half from here.

This is my backyard http://lokeshshah.googlepages.com/D2_ExitGlacierRainbow.jpg

TOTALLY kidding. It's from Alaska so it's probably Chocolatemoose's backyard.

Luckily we don't have any glaciers either. LOL

hart, our summers tend to be hot, humid, and dry in July and August here- I'm thinking not too far off from your climate, and Dahlias do very well for me. Most years I set them out in late April with good results. We've had temps in the 80s for several days running, so I got mine planted a few days ago and am already seeing some sprouts. I was really impressed with how well the Dahlias dealt with the drought last summer, even after watering restrictions set in. Most of mine were in full sun last year, where they got the brunt of the heat of late afternoon, and they took it like troupers, so I agree with Dahlianut and don't think you need to be too concerned about too much sun.

That's really good to know, Neal. I'm more worried about the dryness than anything. It helps a lot when I have decent soil and mulch but where there's nothing but rocks underneath, it still dries out pretty fast when it's so hot.

The one dahlia I've been growing for years is in a bed that gets shade in the hottest part of the afternoon and so I don't really have anything here I can use for comparison to the areas with full sun.

Would you consider using the moisture holding polymers?

I use them in for my dahlias in containers and it has really reduced the amount I have to water.

Yes, I use those. It helps a lot when I improve the soil and usually I put in a lot of nice, new soil, peat moss, compost, anything I can get my hands on.

When I'm talking about rocky btw, I don't mean soil with a lot of rocks. I have parts of my yard that are nothing but rocks and some ground up, sandy former rocks.

I have another question. I was looking at members' garden photos at some of the dahlia society sites last night and many of them showed shade structures and even umbrellas over the dahlias. So if they need full sun, what was that all about? The umbrellas were pretty cute, I have to say. LOL

Sometimes the umbrella is to protect a good bloom meant for a show from rain or fading from excessive sun. I have contemplated the umbrella thing after a few ginormous blooms got pasted by a good rain. Those things weighs several pounds sopping wet! :) A structure with shade cloth could benefit you as far as intense sun.

Thanks, Tod. That makes sense. I've had big blooms from my one existing dahlia weighed down with rain water. Peonies too. I'll bet the shade cloth keeps them from getting pounded by rain as well as providing shade.