Gardening

Drought resistant plants in an urban courtyard garden

  • 25 June, 2017

I just got back from a two week holiday and although I have quite a few plants growing in pots in the garden I didn’t really give them much though on leaving as we nearly always has some degree of wet weather here in Bristol. Also, most of the pots have a tray of some description to retain water from rainfall or watering. Most of the time I worry about the plants being too wet as some of the trays I have are just old kitchen bowls etc that have turned up from somewhere and have been used for mixing compost with pearlite or grit etc when potting up. As I’ve introduced a new plan I’ve grabbed one of these to act as a water tray and there it’s stayed.

However, not all of the pots had a tray underneath and uncommonly for June we had a heatwave of up to 34 degrees and no rain.

I started being concerned about this while away but had no way of getting them watered so was interested to see how things had fared on my return.

The birch was the first thing that I saw with yellow and brown leaves, it was actually much worse than the pictures, but I was too fast to start tidying the plant up before taking a picture, simply imagine more brown leaves closer to the main stem.

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I wasn’t worried overly worried about this about this as the tree had been rescued form a woodland that we planted of approximately 416 trees. The trees were all British natives and were bare root plants ranging from whips of about 1m to standards at approximately 4m in size. The birches were the exception and were all supplied in containers (pots) of about 10L, the site for the planting was on a windswept hill with no irrigation beside a very low pressure tap that wouldn’t reach the far side of the site of approximately 500m away. The birches suffered more than any of the other trees and some of them yellowed and lost some of their leaves even though a lot of these were nearest to the tap and watered more. All of the trees on the site had been planted in a good tree planting compost and well mulched. I suspect that one of the reasons that the birches struggled was that the compost that they were supplied and grown in didn’t re-wet well once dry, In a nursery they would have been drip fed with water so it is unlikely that this would happen but when they get to site it is a very real possibility.

Also, birches just don’t have a very good drought tolerance, as they have none of the mechanisms available to other trees such as a waxy leaves, the ability to turn the leaf from the sun, a light underside of the leaf that can curl and reflect the sun or needle type leaves. As our plants hadn’t had any time to get their roots into the ground to find water reserves and none of these defences available they yellowed, browned and lost some of their leaves, after a phone call from the client suggesting that ALL of her trees were dying I got out there pretty quick to have a look. It was a bit disturbing to see the yellowing of the birches at first but on inspection I could see a new bud on all of the leaf stems. They all came through well.

The third picture above shows the tree that was saved from the site discussed, it is a Betula pubescens – Downy Birch or White Birch, this tree likes damper conditions than the more common Betula pendula – Silver Birch, it’s main stem somehow got snapped and left just a small branch which has gone on to become the leader and new trunk.

 

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Above you can see new buds by a failing leaf and also where leaves have fallen, you can use the fallen leaves to mulch below the tree (you wouldn’t do this if the leaves had fallen through disease). The tree is still in its original pot but I have it stood in another larger pot that I intend potting it up in to. I am keeping it in a pot as we have a small garden and birches can get pretty large. The larger pot has no holes in at the moment and this may have helped the Birch along as I watered before we left. The other little plant is a sedum aurea that I popped onto the soil of the pot before we went so that it had some access to water through the bottom of it’s pot.

The other pots in the garden were quite interesting in how they fared with the drought. In the first blog picture you will see two foxgloves that are very dry and extremely wilted and basically dead and a Hosta ‘sum and substance’. The hosta I would have expected to have suffered more as they are generally more associated with damp and shady environments. The foxgloves (Digitalis purpurea) are a woodland plant and will grow in sun or shade but are most commonly thought of as liking partially shaded light dry soil. Looking at the native habitat of a plant will give you the best chance of understanding what it likes in order to grow best, Woodlands can be shady and damp with a humus rich soil but often woodlands are dry shade. The plants were in the same size pots and in a slightly shaded area, the foxgloves were decimated and the hosta was as good as it was when we left.

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More later. A.