Question
QUESTION: Hi LIG...

I live just north of Atlanta, GA and I have a question about my dahlias.

I purchased a couple of potted dahlias from Wal-Mart and initially, I transplanted them into a bigger pot.  One day when I came home from work, I noticed the leaves on the larger plant were a little brown and crispy.  I also noticed that the flower buds turn brown and die, never opening up.

Today, I decided to put them in the ground and when I did, I noticed on the lower leaves, my friends, the leaf miners, have been hard at work.  I put down some Bayer Flower and Rose Care Fertilizer (with insecticide) to take care of that little problem, but why are the leaves turning brown and the buds dropping?  I don't over water them (I've learned that lesson the hard way over the years) and originally, they received morning sun for at least 5 hours.  Where they're now planted, they should receive at least 6 to 8 hours of full sunlight.

So Far, it has been a wet spring/summer with the forecast of scattered showers another 3 days this week--could this be the culprit?

Thanks in advance for your help.

ChiTownDivaus

ANSWER: ChiTownDivaus,
Brown buds and leaves can be caused by any of the following, or a combination of the below:
1. Fertilizer burn. If the plant has too much fertilizer it will "burn" the leaves, browning the newest foliage and buds first. This is likely to happen if a plant has been fertilized with a synthetic fertilizer (liquid, granular or time-release) when it is dry, or anytime fertilizer is applied at too high a concentration.
2. The plant goes too dry in-between waterings. When the roots get too dry in between times when the plant is well watered, the foliage and buds turn brown.
3. Fungal problems: if the weather is wet and cool, and foliage and buds are constantly damp, fungi can cause either leaf spot or browning of buds.  Fungi are unlikely to cause an entire leaf to brown, however....usually just spots of the leaf.

From now on I'd do the following: no more fertilizer for awhile, including the Bayer product.  Water deeply less often: when you do water, use a soaker hose or sprinkler and leave it on for at least an hour and a half - so that the soil is deeply soaked and then you can wait for another four to six days to water again.  Spray the foliage with Serenade if you think fungus is the problem. Serenade is an organic fungicide (red bottles, available at garden centers) that helps get rid of "the bad guys".

I hope this helps,
C.L.

---------- FOLLOW-UP ----------

QUESTION: Hi CL...

Thanks for responding to my question.  I use soaker hoses in my garden so I should be good there.  The weather this week is suppose to be hot, hot, hot--in the 90s hot!  So you're saying that I don't need to water the dahlias for another 4 or 5 days?

Thanks

Answer
Because the moistness of the soil depends not only on the temperatures but on the type of soil you have, judge by the look and feel of it. If you dig down about three inches and the soil is moist, don't water. If, however, the soil is dry three inches down you should water deeply and then wait until it is dry again before watering again.  It is possible that you might have to water a bit more frequently while the plants are getting established (if you recently planted them) but after they've been in place for a month they should need less water.

Clay soils or those high in organic matter will retain water longer, while looser soils or sandy loam will need watering more often. But no matter what type of soil you have it's always better to water deeply but less often, especially once the plants have gotten established - so keep those soaker hoses on for a couple of hours and soak the bed well, then don't water again until the soil is dry.  A deep soaking will help the plants develop deeper root systems so that they are better able to withstand hot, sunny weather.

I hope this helps,
C.L.