Expert: C.L. Fornari - 4/7/2008

Question
I live in So. Calif. My sister planted over 50 small impatiens all over the yard,
some in containers, some in the ground. Most are thriving! Some died in two
weeks. The ones that died are right next to ones that are thriving. However,
in one spot in the garden, six died in a row. Perhaps it was a bad "batch" in
the nursery. My neighbor thought I was overwatering (every day). Now, every
other day. They get sun, partial sun, and shade, depending on the time of
day. However, during the day when there would be no shade, it's been
overcast.

Answer
Mary,
My guess is that your neighbor is right - even for new plants, watering every day or every other day is too much if the plants are in shade or if the weather is cloudy, especially if the temperatures are below 80 during the day.  New plants don't have that many leaves to support, so they don't take up as much water. If the soil feels damp one inch down from the surface you don't have to water.  In general, a deep soaking less often is better than a little every day. Frequent splashing of impatiens foliage causes leaf-spot fungus - plants get spotted leaves that then turn yellow and drop off. It can also cause crown rot where the stem area that is next to the ground gets a "water soaked" look and the plant wilts and keels over.  This is also caused by the fungi that flourish in very wet conditions.

You want to allow the very surface of the soil to dry out between waterings, but as I said you want the soil an inch below the surface to be damp when the plants are small - once they get larger, and have larger root systems, you can let the soil dry out to two inches down.

Always water in the morning so that the foliage has a chance to dry out, and whenever possible water with a sprinkler not by hand - people get bored LONG before the soil is soaked down to six inches, which is what you want. Deep watering makes for deep root systems, and a plant with a deep root system can go longer between waterings.

The four that died in a row might have done so because there were more fungal spores in that area to grow and attack stems or leaves.

The good news is that it's early in the season, so you could replace those plants if you wish and in three or four weeks you'll never know that they were planted at a different time.

all the best,
C.L.