How long can trees survive in flooded ground?

13 Jan 2016

This recent spell of wet weather is a challenging time for trees that find themselves in the wrong place. A tree seed germinates where it lands and can grow for years before a calamitous event comes along to kill it. Unlike animals, plants can’t just get up and move from their position if it turns against them and this is one of the reasons why it takes more than a million tree seeds in nature to produce one single mature specimen. Like Turtles, Trees adopt the ‘pot luck’ approach to reproduction and rest all their hopes on the volume of seed produced.

Tree roots need oxygen as well as water. Too much oxygen and they die of drought, too much water and they drown. Newly planted trees that have been in the ground for less than 5 years are more prone to suffer in waterlogged areas as their root systems are less expansive that established trees. If a recently planted tree is waterlogged it is important to dig drainage channels and get the water away from the drowning the root system. Prunus (Flowering Cherries) are particularly sensitive to being saturated whereas Malus (Flowering Crab Apples) are more tolerant, but in any case if the tree’s roots are under water for over a week this can be really bad news. In the worst case the tree simply dies but in many scenarios the trees flush a pale yellow in the spring and succumb to bacterial canker and ooze over a longer period before failing.

There are however some water specialists that can lengthen the odds. Willow (Salix), Alder (Alnus), Poplar (Populus) and Swamp Cypress (Taxodium) all like it wet and once established can tolerate waterlogged ground for several months when dormant. Please see our guide to these genus on the following link: www.barcham.co.uk/tree-finder/#wetland . This range can be particularly useful for gardens that are near rivers that routinely flood in winter.

If you are worried about the way your garden gets saturated in the winter you can always adopt an old Victorian planting tip by mound planting. Only half bury the container root system and raise the soil up and over the other half to get the root system above any flooding issues that may come along later. Be sure not to make a steep mound that can erode, graduate a couple of metres in width and plant the tree at the top of it. Ironically this means greater attention to detail on watering in the first spring and summer but this is nothing that one of our Tree Hydration Bags can’t sort out! Planting a tree too deep can exasperate flooding worries as the roots are pushed lower down into the water table and are therefore deprived of oxygen.

I hope this helps answer a few questions but remember we are only a phone call away for further information!

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