We ask our volunteers to keep watering even though a lot of rain might fall during the growing season. That’s because street trees are growing in a pretty hostile environment and fragile saplings need help to adapt. Their roots have been constrained into a small ball at the nursery and have to be trained to spread and deepen. They’re planted in just a shallow layer of topsoil and must contend with rubble and all sorts of sub-surface works.

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Surrounded by paving or tarmac and with only a tiny square of earth open to the elements, they can’t take advantage of rainfall in the same way as a tree growing naturally in a wood or field and they can’t reach down for groundwater either. It doesn’t help that the tree pits are sheltered from the rain by the green watering bag and the leaf canopy also deflects it away. What looks to us like a heavy, soaking downpour will in fact be mostly lost to run-off.

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Clearly, if we get continuous heavy rain for a long period it’s wise to hold off watering. A prolonged storm can saturate the soil to the extent that oxygen can’t get to the roots and the tree suffers. The blocked pores beneath the surface will need a chance to dry out before you water again.

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But if we’re just getting showers or the odd day of rain do keep going with your watering routine. The Treegator is ideal for newly planted trees because it lets water percolate slowly through the soil over several hours, encouraging deep roots that will eventually be able to tolerate drought.

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Here are some professional links that might be helpful:

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Arboricultural Association

• Watering young trees in dry weather

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Tree Council

• Managing and caring for trees

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Trees for Cities

• Watering urban trees

 

Barcham’s nursery

• Watering newly planted trees (Barcham’s supplies much of the council’s stock)

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Treegator

• How often to water

 

Treegator

• How to use the bag

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London Tree Officers Association

• Water management guidance.