As the sun climbs steadily in the sky and the weather becomes warmer and drier, our street trees are gearing up for a rapid growth spurt. The saplings will be thirsty and their older cousins will be needing a bit of care after months of dormancy. We plan to resume minor maintenance work and street visits in early May, Covid permitting, but in the meantime the focus has to be on watering.
Watering guidance
The council is now planting the last batch of trees for the 2020/21 season, so within a few weeks there will be almost 60 new arrivals here, each needing a regular soaking to encourage deep root growth. It’s largely up to us to make sure they survive any heat stress and drought. Southwark’s maintenance teams are contracted to water new trees, but we’re waiting to find out exactly when they’re due to start and how often they’ll visit.
Our target is to work up to delivering around 50 litres of water a week to each young tree in the summer months (May-August). You can start with a lower figure in March and April and slowly cut back again through September and early October, but if at any time the weather is especially hot, dry or windy do increase the volume. You’ll know if a tree is getting stressed from lack of water because the leaves will be limp, rather than firm. And don’t worry about giving them too much: you can’t over-water young trees but you can easily give them too little.
Every new tree has a green Treegator watering bag zipped around the trunk which releases water slowly, allowing it to reach down to the roots instead of running off into the gutter or along the pavement. There’s a square cut out of the metal tree cage where your hose or watering can goes in. Always aim for the little slit between the two straps at the top of the bag otherwise the water will just pour straight through. And if you come across a faulty Treegator that’s not filling or emptying properly please let us know and we’ll ask for a replacement.
The bags can hold about 55 litres but you don't have to fill them to the brim in a single weekly visit. Water is very heavy to carry so it’s perfectly all right to space out your watering trips over a few days, as long as the weekly total in summer is about 50 litres (11 gallons). Keep up the routine for the first two or three years after planting, so don’t leave out the young trees from the previous couple of seasons.
Here are some links that might be helpful:
Arboricultural Association Watering young trees in dry weather
Tree Council Managing and caring for trees
Trees for Cities Watering urban trees
Barcham’s nursery Watering newly planted trees (Barcham’s supplies much of the council’s stock)
Treegator How often to water
Treegator How to use the bag
London Tree Officers Association Water management guidance.
Early spring blossom
The beauty of spring blossom is inevitably short-lived. The photos attached below were all taken on Saturday 27 March but six days later, after a spell of light winds, the gorgeous Yoshino cherry avenues of Stradella Road and Winterbrook Road are now almost stripped of flowers. The buds first opened up around the 15th of March, so the 2021 Herne Hill ‘hanami’ - the name given to the cherry blossom viewing festival in Japan - lasted less than three weeks.
Both streets looked amazing this year. The Stradella Yoshinos, including some sizeable trees, are mostly on the odd-numbered side, but on Winterbrook the few remaining gaps on both sides are being steadily filled in until the avenue is complete. Yoshinos (Prunus x yedoensis) are becoming more common on other local residential streets and you’ll spot them at places like Melbourne Grove in East Dulwich.
Yoshinos have what are known as single flowers, with one set of petals, like a wild dog rose, but you'll find double flowers (multi-layered petals, as in a hybrid garden rose) on many of the other ornamental cherries that are just starting to bloom, like the young tree pictured at 54-56 Beckwith Road.
If you get a chance, take a walk over to Casino Avenue for the annual festival of magnolias. These too won’t last much longer, so enjoy them while you can. Most of them have white flowers but three are a stunning deep shade of pink, like the one pictured at no. 112.
Southwark plants five kinds of magnolia - Magnolia Galaxy, M. Grandiflora, M. kobus, M. x loebneri 'Merrill' and M. x soulangiana - so if you’re a keen gardener you might be able to identify which varieties we have on Casino.
The Guardian ran a photo feature on Tokyo’s hanami on the last day of March, alongside a thoughtful editorial which concluded “This year, as we remark on the fleeting beauty, we should also remind ourselves what we are doing to nature. Though we cannot cling to its gifts, we have a duty to cherish them.”
Catkin season
The many birches around Herne Hill are in bloom too, but their flowers - which we know as catkins - are seriously understated compared to cherries and magnolias. Birches are monoecious trees, which means they have male and female flowers on the same tree. The smaller female catkins, which stand upright, appear in the spring and thicken later in the year, but the classic hanging catkins are all male and may have been on the tree all winter.
The long male catkins on the tall silver birch (Betula pendula) outside 34 Stradella Road, pictured below, are looking particularly graceful.
Birch catkins grow in groups of twins, triplets and even quads, as you can see from the close-up of the young downy birch (Betula pubescens) at 26 Elfindale Road. If you zoom in you’ll see how each male catkin actually encases multiple tiny flowers.
Elfindale is a great street for birch-watching. You’ll be able to pick out the silver birch by its elegant drooping branches; the downy birch, browner than the other types; the paper birch (Betula papyrifera) with its peeling bark; and the bright white Himalayan birch (Betula jacquemontii), now increasingly common round here. Of all the different species, though, only the silver birch and the downy birch, with its brown bark and branches, are native to Britain.
Other members of the birch family also produce catkins, although at different times of year: alders (on Stradella), Turkish hazels (on Beckwith, Holmdene Avenue and Danecroft Road) and hornbeams (most easily seen along Lover’s Walk, which runs between Gallery Road and College Road).
New arrivals
We reported in the last newsletter that we were expecting 42 more trees to be planted by the end of April or the start of May. We’re pleased to say that three of those newcomers are already in the ground: an Umineko cherry (Prunus 'Umineko') opposite no. 1 Ruskin Walk and two more Yoshino cherries on Stradella, one facing no. 1 and one on the bend outside no. 50.
Still pending
So where do we stand with the other 39 trees on this season’s planting list? You can check their status in this spreadsheet:
Here’s an outline of the situation at the end of March:
Twenty-one tree pits on the pavement are now ready to be planted
Six more tree pits still need to be dug
Another seven trees could be put in without delay on grassy areas along Casino Avenue, Red Post Hill and Sunray Avenue, where no pits are needed.
Five locations might need a bit more work before they’re ready to be planted.
Those five are at:
16/18 Sunray, where a dead liquidambar needs to be removed from the grass verge
51 Hollingbourne Road, where a small tree was blown down last year
37 Half Moon Lane, where a big hole was left after a London plane stump was removed
113 Sunray Avenue, where the kerb might need some attention before the verge can be replanted
the corner of Elmwood Road and Frankfurt Road, where another big plane stump is still in place.
The other eight tree stumps that were standing three weeks ago have all since been ground out.
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