Hi Sherry, 

Thanks for reaching out with your question. I'm sorry you were having trouble with your old shasta daisies but glad you're trying again with new plants. Happy to also hear you are  mulching and regularly watering them. Those are both great ways to care for these perennials. 

When establishing the new plants, make sure you're watering them a few times a week as they get established. As the season progresses, I would also recommend deadheading any spent flowers. This CSU Extension fact sheet has a great overview of perennial care that you might find helpful. 

One additional question - did you ever divide your old shasta daisies? We recommend dividing your perennials after 3-5 growing seasons. If the plants get too overcrowded, they will bloom poorly or not at all. 

Thanks and happy gardening! 

Katie G., El Paso County Master Gardener

Hello Sherry,

I am another Master Gardener and I wanted to also mention that the white powdery substance on the leaves may be powdery mildew.. They affect virtually all kinds of plants: cereals and grasses, vegetables, ornamentals, weeds, shrubs, fruit trees, and broad-leaved shade and forest trees. 

Powdery mildews are characterized by spots or patches of white to grayish, talcum-powderlike growth. Tiny, pinhead-sized, spherical fruiting structures that are first white, later yellow-brown and finally black, may be present singly or in a group. These are the cleistothecia or overwintering bodies of the fungus.

Powdery mildews are severe in warm, dry climates. This is because the fungus does not need the presence of water on the leaf surface for infection to occur. However, the relative humidity of the air does need to be high for spore germination. Therefore, the disease is common in crowded plantings where air circulation is poor and in damp, shaded areas. Incidence of infection increases as relative humidity rises to 90 percent, but it does not occur when leaf surfaces are wet (e.g., in a rain shower).

Here is a fact sheet that also mentions possible ways to control for powdery mildew should the problem arise again.