We’re in the first days of summer and the sun is finally shining, but it’s been a puzzling spring. After an exceptionally cold and dry April we’ve just been through a very wet and windy May, and it’s only in the last few days that the sun has stayed out long enough to give our young trees the growth spurt they need.
Tree Watch on your street
Now the good weather is back and pandemic restrictions are being lifted we’ve resumed our programme of street visits. During May we spent an hour or two with our friends on nearly every one of our 23 streets, looking at the new plantings, checking on the watering situation, identifying gaps that need filling, carrying out some minor maintenance and reporting back to Southwark on more serious issues.
We had one rainy but enjoyable session with the Burbage Road Residents Association who wrote this very kind report to their members:
“Do you know your Himalayan birch from your liquidambar or your Chanticleer pear? BRRA members Tyrrell, Anne, Charles and David joined Jeff and Paul, of Herne Hill Tree Watch, for a Saturday stroll along Burbage Road in May, with a touch of light maintenance for good measure, ensuring our very many beautiful trees stay that way.
“Herne Hill Tree Watch is a community group caring for street trees on the Southwark side of Herne Hill, with a direct line to tree officers at Southwark. You can learn a lot from knowledgeable neighbours and help to make a difference, just by noticing the trees as you walk past and reporting thirsty young saplings.”
Why water trees when it's been raining?
We’ve been asking our volunteers to keep watering even though a lot of rain has fallen in the last few weeks. Part of the reason is that this year’s planting season has been delayed by a couple of months and the trees that have only recently gone in have a lot of catching up to do.
But even in a normal year we still need to water our young trees despite spells of rainy weather. 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.
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.
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.
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.
Watering in the early morning or evening is best, otherwise the summer sun can evaporate the moisture. And if your tree is unusually big - like the aspens, planes and some ginkgos and birches that have gone in recently - give them more water than normal. Even though they look strong, they take longer to establish than a little sapling.
More new trees in the ground
The council has continued planting through May and by June 5 had achieved a total of 51 new trees for Herne Hill since November/December. It’s a great result - two extra trees on average for every street in the neighbourhood, beautifying them, keeping them cool and shady and contributing to the fight against global heating.
Paul has worked out that there are now over 900 trees in the roads we cover, which means that these 51 new ones have boosted our street tree population by about 6%. Let’s try to keep up that growth rate in the years ahead.
The range of species has been very broad, which will help build the diversity we need in a changing climate. Since the beginning of May Casino Avenue has welcomed a new hornbeam, a swamp cypress and a golden Indian bean tree. There’s been a whitebeam for Nairne Grove and a quince for Sunray Avenue; a pair of London planes for Half Moon Lane and another for Elmwood Road; Himalayan birches for Frankfurt Road and Burbage Road; an Umineko cherry for Elfindale Road; and finally a Yoshino for Hollingbourne Road.
You can see the full list of plantings for the entire season here. The table also shows there are still 10 missing trees that were scheduled for 2020/21:
A tassel cherry at 36a Carver Road.
A ginkgo opposite 8 Casino.
A Himalayan birch at the top end of Elfindale, alongside 77 Herne Hill.
A London plane to replace the stump at the junction of Elmwood and Frankfurt.
Two Henry's limes on Red Post Hill, at 42/44 and 56.
Two almonds in the garden square outside 49-71 Sunray.
And two Yoshino cherries opposite the Baptist church on Winterbrook Road.
Paul and Jeff will be seeing Julian Fowgies, the Arboricultural Services Manager for Southwark, and Ernst Erasmus, the arboricultural officer for the south of the borough, in Herne Hill on June 10 and we’ll take the opportunity to find out what their plans are for the outstanding trees. We’re also going to be discussing with them the plan to complete the Yoshino planting scheme on Winterbrook, which still has a few gaps to fill.
Late bloomers
Most of the spring blossom has blown away by now, but it’s been a good year for flowering trees in the rose family (Rosaceae). That group includes cherries, almonds, peaches and plums (Prunus), apples (Malus), pears (Pyrus), hawthorns (Crataegus), medlars (Mespilus), photinias (Photinia) and whitebeams, rowans and service trees (Sorbus).
The Swedish whitebeams (Sorbus intermedia), like the one below opposite 131 Casino, have put on a good display this season. It’s got the classic whitebeam foliage - glossy dark leaves with a pale, furry underside - but with scalloped edges.
A little further along the road at 122 Casino the vivid red blooms of the Paul’s Scarlet hawthorn (Crataegus laevigata 'Paul's Scarlet') lit up the street almost up to the end of last month.
May is traditionally the time for hawthorn blossom (known colloquially as mayflowers) but the pretty cockspur thorns only began opening up in the final week of the month. They’re much more shapely (and much less thorny) than the native hawthorns and have glossy oval leaves, not lobed.
This broad-leaved cockspur thorn (Crataegus prunifolia) outside 35/37 Half Moon Lane is clearly attractive to wildlife: it’s been buzzing with bees since the flowers emerged. Come autumn the foliage will colour beautifully and it will be covered in small red berries.
Over on Hollingbourne Road, outside no. 19, there’s a hybrid cockspur thorn (Crataegus x lavallei), also in full flower. It’s a similar tree to the broad-leaved species but with a more upswept, wineglass shape, and its shiny dark green leaves and big orange fruit stay on until the winter.
Two more unusual street trees complete this month’s selection: a laburnum and a tulip tree. There used to be two laburnums (Laburnum X watereri 'Vossii') on the little strip of grass outside Sunray Gardens, by the pedestrian crossing over to Charter School. But one of them died last year and eventually keeled over in the wind this spring.
It was replaced by the council with a ginkgo and immediately the laburnum’s cousin a few yards away, which had also looked wretched for the past couple of years, sprang defiantly back to life. It put on a brilliant show of yellow pea-like flowers, hanging in long, drooping clusters.
If you’re quick and you’ve got the patience to look carefully, you can catch this year’s tulip tree (Liriodendron tulipifera) flower show. The creamy yellow blooms, pictured here on the tree at the corner of Howletts Road and Warmington Road, aren’t easy to spot, dotted about high up in the lush dark green foliage, but once you find them you’ll immediately understand how this tree got its name.
You can find other tulip trees on Beckwith Road, Burbage, Hollingbourne, Holmdene Avenue (two) and Stradella Road.
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