What are the effects of flooding on plants?
The recent torrential rainy weather has made us all think about the effects on our homes and gardens. Claire King from the University of Reading (funded by the Royal Horticultural Society) is researching the effects of flooding on lavender, stachys, cistus and common sage. She has been flooding plants for either three or 17 days during the spring, summer or winter. Surprisingly, no plants died when entirely flooded in winter for 17 days, but about a third of the sage and cistus died when they were flooded in the summer. Summer flooding causes the most harm, as plants are in active growth and not partially shut down. Claire found that when the plant is drenched slowly, it has time to adjust by making new lateral roots near the surface, whereas sudden flooding causes more damage. If your prize plants are flooded, lift them, if possible, and pot them up adding some freedraining compost. You may need to cut back the top growth a little to compensate for the death of some roots, too.
