I have a request by King County (Seattle) area to write specifications for woody vegetation planting requiring the use of slow release (8 month) high nitrogen, low phosphorus granular fertilizer (21-3-7) and SoilMoist (or equivalent moisture retention agent).

The County indicates that amongst arborists and landscape professionsals consulted there is some disagreement regarding such augmentation, but maintains that there was increased success when moisture retention agents were used.

It is my understanding that wetlands professionals are moving away from use of admixtures in plant pits as a means of encouraging roots to go beyond the plant pit in search of nutrients and water. Of course, supplimental irrigation may be necessary during at least the first year of plant establishment, with the assumption that late fall planting is preferred, depending on wet season hydroligic support to support root establishment and migration.

I apoligize for this lengthy posting, but would like to hear from others who have wrestled with this issue. Thanks. You can also reply directly to me at tonyroth@comcast.net

I am unaware of any published rational standards for fertilizer in wetland plantings. If you are planting into a soil with higher organic content there should be no shortage of Nitrogen. On the other hand one of the primary effect of flooding soils that are high in unavailable phosphorus is to release large quantities of phosphorous. Also, are your soils demonstrably low in nitrogen or high in phosphorus. This is very confusing. The ordinary way to deal with this is to use a balanced slow release fertilizer and to put it in the planting hole. This method assures that the plants' needs will be met and that the nutrients do not run off the soil surface. Do they want the fertilizer put on the soil surface or in the planting hole? Agriform tablets are a good choice and were originally designed for woody plants. I have used them with excellent success in a number of wetland forest plantings.

The water retention agents are good if the plants are not handled properly and might dry out during the planting. They might also help with water retention in the soil. But if the planting is done well and the plantings are irrigated what is the purpose of all this extra bother and expense.