Writings from Wales March 2013
We finally finished tidying the garden midmonth and so I can start my favourite spring past time planting up the new borders. Of course autumn is usually the recommended time for planting, and it is true that, given good conditions, plants can make some good root growth in autumn and early winter. However, in a wet site like ours, and with the small size of plant usually sent by mail order, we have had losses with plants being unable to cope with the occasional waterlogging. Spring planting has been more effective for us, but we do have to be willing to water if the spring is dry.
Over the past 3 years I have been developing a new woodland garden under the shade of an old oak. It is quite a large site (20 m by 17 m) and I have been developing one quadrant per year. I have settled on a fairly robust procedure. We kill off the vegetation with glyphosate in the summer and clear the site of any remaining perennial weeds by hand in autumn. There is one fundamental rule for making gardens under trees. DO NOT DIG. Breaking up the trees root system can lead to the slow decline and death of the tree. And even if it survives, it will do so by pushing new feeding roots into the bed you have planted. Instead build the planting medium up on top of the existing soil. Woodland plants do not root deeply. They need a good, humus rich medium, but it need not be deep. I apply layers of garden compost, leaf mould and the contents of ditch clearing (see last months column) to a depth of about 6 ins and let the worms mix it up for me. I include small sticks and other woody material in our compost bins which makes for a good open medium for woodland.
I like to grow many plants from the woodlands of East Asia, where the plants get dry winters and wet summers. The extra height of the bed helps drainage in the winter and I lay a leaky hose over the site and then cover it all with a layer of part rotted shreddings as a mulch. In a normal year I only have to use it a few times in very dry spells. In my experience many mature trees do not try to root up into this layer. I think that their main area of root activity is at and beyond the drip line, and closer in they behave themselves. An exception to this is willows, which are only suitable for supplying dry shade.
The first quadrant is now reasonably well established. I have planted some small understory trees including a Hydrangea heteromalla, an Acer palmatum and Alangium platinifolium. The latter is a lovely thing with dangling white flowers with reflexed petals and exerted, bright yellow stamens. The next layer includes some rhododendrons (macabeanum, sinogrande, x loderi etc. that may eventually be part of the understory) and quite a few cultivars of Hydrangea serrata. Then we come to the herbaceous layer. I plant fairly randomly to get a natural mix of arisaema, podophyllum, aralia, epimedium, polygonatum, disporum, tricyrtis, actaea etc. Not at all artistic, but it looks good to me!
Some of the early flowering shade plants are beginning to appear in the garden in spite of the late spring. Last year I started to buy varieties of arum with good leaf shape and markings. I particularly like Arum Tiny.
I have struggled several times to grow Chrysosplenium macrophyllium. It needs a very moist soil, seems to hate being waterlogged but cannot cope with even a short dry period. I think I have finally been successful. It is in flower at the moment. I wonder whether my current success is due more to there being different clones around, some being less fussy than the others.
The corydalis have also started to flower. Corydalis malkensis is a particular favourite (see below). It is slow to bulk up and does not seem to self-seed as freely as Corydalis solida. I think I will try to collect seed this year.
Finally a mention of hepaticas. I like them but I cannot grow them well. I have read the books, and I try, but although they survive, they do not thrive. One exception is Hepatica x media Harvington Beauty. It is a hybrid between Hepatica transylvatica and Hepatica nobilis. It is vigorous, easy to please and produces masses of mid blue flowers. If you want to try hepatics, please start with this one, it will encourage you to persevere.
Text and photographs by Joe Sime of the HPS Shropshire Group.