Recovery from Flooding

The exact amount of time a turf surface can survive completely submersed is not definitive. The time tolerated differs between species and is also impacted by the time of year, depth and quality of the water. With winter flooding the likelihood of recovery is much higher due to the grass being relatively dormant. With minimal levels of growth through the winter due to the low temperatures the plant’s respiration requirement is low and the period of tolerance extended.

Summer flooding, though less likely to occur in the first place, is likely to cause more damage if it is prolonged. The higher temperatures will make it more likely for algae to form, blocking out sunlight and leaving an unwanted layer over the surface once the waters recede.

Nature always tends to find its way, so with flood prone areas tending to be in lower lying it is expected to see the turf dominated by perennial ryegrass and bentgrass (also annual meadow grass). These two species can cope well with extended periods of flooding.

Tall Fescue has a noted ability to tolerate being submerged, although it is very rarely found in golf course fairway mixtures due to its coarser texture. Older varieties were not only broad leafed, but also very dark in colour. However, breeding advances in this species may present an opportunity worthy of future consideration – tall fescue is highly tolerant of drought conditions as well as flooding, so might be a solution as extreme weather patterns become the new normal.  Keep an eye out for new varieties such as Baraline and Bardesta, which are resemblant of a better-quality ryegrass, with a much better texture and paler colour.

For areas that are underwater for extended periods, some level of die back is to be expected. In such areas there will likely be a slime-like layer of decomposing material that once dried will form crust over the surface. If overseeding is required to reinstate the surface, the first thing is that it must of course be dry enough to work on and operate machinery. But even then, the soil conditions are likely to be unfavorable to drill straight into.

Decomposing organic material will contain toxins that inhibit seed germination. If dry enough to do so, scarifying off affected areas to remove the organic deposits is recommended. It is important to rejuvenate the soil, so opening the surface by solid or hollow tining will improve airflow in the soil and be of benefit to soil life. Aeration holes will also make an ideal ‘pot’ into which seed can be broadcast.

When it comes to choosing a seed mixture overseeding and repairing flood damaged areas, the best option would be to choose a 100% perennial ryegrass blend.  Suggested products would be our Ultrafine 100, Extreme or RPR Golf blends. Why choose 100% perennial ryegrass?

• On winter flood damaged areas the priority is likely to be getting the area beck into play as soon as possible. Perennial ryegrass has the fastest establishment time and is superior to other species for germinating in cooler spring temperatures.
• If the area is prone to flooding or if the ground is naturally moist, it is unlikely that fescue would not tolerate such conditions in the long term. In areas where ryegrass is naturally prevalent it makes sense to stick with it. Bentgrass, although tolerant of damp conditions, is generally not used in current fairway mixtures. At a fairway height of cut, a good quality perennial ryegrass offers a superior surface to bentgrass, not to mention far superior tolerance to wear.

Finally, it is also important not to forget about nutrition on fairways that have been flooded. Although heavy land might not need much encouragement in terms of growth due to the rich soils, lighter soils could be quite depleted. An application of an appropriate fertiliser will help with recovery of existing and establishment of new grass plants.