Expert: C.L. Fornari - 6/19/2007

Question
I have 7 tidal wave petunia plants that are starting to dye and I don't know why, I water them 2 times a day once in the morning and once at night and they get 7 or more hourse of sunlight.  I am not by any means a gardener, trying to keep things alive for the first time, so any help would be great.

Answer
Jan,
It sounds like they are getting too much water - plants need a good soaking every few days and then time to dry out a bit in between.  If petunias have roots that are constantly wet they rot, and the leaves wilt and turn yellow.  I know that this is confusing to a new gardener because the signs of wilting from too much water look just like a plant that is thirsty, so the natural response is to water them more.  

Newly planted annuals might need watering every morning in very hot (85 degrees and above) sunny weather, but as their roots grow wider and deeper they are able to go longer between waterings.  So the first week they are in the ground you could water them once a day in hot weather, and every three days if the temps are below 70 degrees in day OR night.  In the second week water them every other day, and the third week every three days, and finially, most annuals are fine with a every four day DEEP watering in hot weather and every five or six days in cooler weather.

Deep watering is when you set up a sprinkler and leave it on for 45 minutes to an hour and a half.  Handwatering does not wet the soil deeply enough to get good strong root systems established.

A deep soaking less often is better than a handwatering every day, for just about all plants.

Another tip: never fertlize a thirsty plant.  If you use liquid fertilizer, apply it after the plant has been deeply watered.

I hope this hleps,
C.L.