Gold Coast Gardener

September 17, 2006

By Gene Joyner, Extension Agent
Palm Beach County Cooperative Extension Service

Water is considered essential for most landscapes and during much of the year we get regular rainfall. Seasonally though we do have dry periods in which we get little rain for extended periods of time requiring irrigation systems for many landscapes to keep plants looking attractive. Too much water though can be detrimental and during the wet summer season and early fall sometimes we get daily rain and once the soil becomes saturated puddles of varying sizes may form in low lying parts of the landscape and in some cases the water may not dry up for several days or even a week or more.

Plants that are subjected to flooding for extended periods sometimes suffer damage to their root systems by a lack of oxygen. There are some plants native to wet areas that tolerate flooding with no problems and if you have a low spot in the landscape certainly try and put plants in those areas that do like being flooded.

Roots that are kept saturated more than 2 or 3 days often start to suffer lack of oxygen and your feeder roots may die creating leaf loss on the plant or dieback of some of the top. Small plants may have enough damage that they’re even killed and there are also certain landscape plants that are very water insensitive and actually drown after just a day or two of standing water.

A good example would be avocado and papaya. If these are flooded for more than two days with surface water, you’re probably going to have the entire plant die regardless of how big it is. Many garden vegetables and bedding plants are also water insensitive and if they are flooded for more than a couple of days they will get serious root rot and diseases that ultimately may kill them.

Plants just from normal rainfall can sometimes experience leaf diseases, flower blights, or fruit rots and this month is the wettest of the year generally because of the close passage of many tropical storms. Hopefully by early to mid October the rainy season will come to a close and then we’ll be in dry conditions up until next June when the rainy season resumes again.
Make sure in the landscape if we’re not getting any rainfall though that you’re not guilty of overwatering. Most plants, particularly shrubs and trees, can get by nicely on irrigation about every 5 to 7 days. If you have bedding plants or small newly installed plants they may require watering 2 or 3 times a week depending on the location in the landscape.

Even your container plants can be injured by excessive moisture. Frequent rainfall that doesn’t allow soil in containers to dry out often can result in leaching of nutrients very quickly, plus the fact that it sometimes subjects the roots to invasion from disease creating root rot or other serious damage.

Hopefully everything will be fine in your landscape for this wet season and you won’t have any major damage, but if you do see problems that you think might be water related and aren’t sure how to combat them efficiently, contact the Palm Beach County Extension office for free advice. Dial 233-1750 in the north and central county area or 276-1260 in the south county area.