Why did this happen to my annual flowers?

Question

My annual flowers that I planted in pots did well for the first two weeks this year and all of the sudden they turned yellow, brown, and crunchy and slowly died. I planted Geraniums, Pansies, and Petunias. They all got full sun just like they were supposed to. I don't understand. What happened? It's rained constantly here so did they get too much water? I planted them in draining pots, I just don't get it? Here are some pictures:

http://flickr.com/photos/11708454@N06/2655838095/

http://flickr.com/photos/11708454@N06/2655839225/

http://flickr.com/photos/11708454@N06/2656668742/

http://flickr.com/photos/11708454@N06/2655841883/

On a happier note, take a look at my other plants that are doing awesome:

http://flickr.com/photos/11708454@N06/2655831899/

http://flickr.com/photos/11708454@N06/2655834871/

http://flickr.com/photos/11708454@N06/2656683542/

http://flickr.com/photos/11708454@N06/2656664614/

Answer 1

Did you feed them. Like Miracle Grow...first sign a plant is hungry is it turns yellow. And pansies are not for full sun. They cant handle the full hot sun. They are best in a area that gets morning sun which isn't the hottest.

Answer 2

The main cause of yellowing and eventually plant death is overwatering. If they constantly got water from the rain, this could have resulted in overwatering. Plants take slight drought much better than overwatering. You should only water those plants after the first couple inches of soil have completely dried out. They should also be allowed to drain completely after watering before being placed into a saucer or something. Even if they're sitting on flat concrete, the water and residue from the soil could have sealed up the drain holes, preventing the water from completely draining and resulting in root rot.

Another problem could be excessive heat. I had a bunch of tomato plants in pots and a recent heat wave killed them all, even though I kept them watered (the bottom leaves turned yellow, then the plants wilted and died). Unlike plants in the ground, the soil in a pot will heat up excessively some times. This literally cooks the plants' roots, killing the plants.