Diarmuid Gavin: The arrival of March means it's time to get busy in the garden
A few years back we took a Sunday afternoon family trip to Mount Venus nursery in the hills of Rathfarnham. Browsing amongst the leafy aisles which were filled with garden jewels I spied a nicely mature Japanese maple. I squeezed it into an impractical sports car, got it back to the garden and planted it where it could be viewed from the living room. (Young maple tree pictured below.)
I was warned at the time that it was too open a site, quite exposed to the wind and without any shade or shelter... but sometimes I just won't listen! I chose design considerations over the happiness of the plant. It grew a little but really it's never been happy with leaves often being scorched by the end of the summer. A lesson learned… a regret which lingered.
The other week saw some lovely mild and sunny weather and so the garden called. The maple was still dormant, enjoying its winter slumber and so the day was perfect to move this tree to a place it would like to be. It's not a job I would tackle if the tree was any larger - this maple is about 4ft high - or had been in the ground for more than three years as the root ball would simply be too big to handle without machinery. While it's OK to cut some roots, you need to gather a big enough rootball that incorporates the tips of the roots as this is where absorption of water and nutrients occur.
I also like to do this job as close to spring as possible so that as soon as the soil warms up the roots will start growing. Hopefully by the time the leaves start to unfurl, the tree will have settled in. I prepared the new planting hole first - this time in a sheltered, dappled shade area of the garden, adding in some fresh compost - before digging up the tree and re-homing it.
It's also a good time to get some herbaceous planting done. I decided to enhance the area around the maple tree with some suitable shade-loving plants. Brunnera is great for dry shade and the cultivar Jack Frost, with its silvery leaves, is superb for brightening dark areas and, in a month or so, will start to produce bright blue forget-me-not like flowers. I also put in some foxglove, acanthus and epimedium which are all plants that should be happy in this position.
So, what other jobs can you be tackling in March? If your soil is not frozen or waterlogged, you can lift and divide perennials. This could be for the same reason that I lifted the maple - they're not doing well in that area or you just want to make some changes in your planting scheme. The division of them will create new vigorous plants, especially with those plants such as aster and phlox that tend to grow in clumps producing new growth around the outside. Gently tease apart the plant into new plantlets. You can discard the old centre and replant your new stock immediately in a well prepared soil with some slow-release fertiliser. Perennials with deep tap roots can't be divided so leave the likes of oriental poppies, lupins and eryngiums alone, while some such as hellebores, dierama and aconitum prefer not to be disturbed at all.
Other perennials and grasses that you have left overwinter can be cut back to ground level now and the rotting vegetation removed. I skipped cutting back the penstemon. The foliage may provide some protection to the crown in this very cold weather and it can be clipped back in a couple of weeks.
Finally, I got round to pruning some of the shrub roses. Basically you don't want your rose to grow weak and spindly with just a few flowers on top so you cut back the stems to a half or a third of their height, making the snip just above a bud which will keep the bush more compact and encourage new growth. Remove any dead wood and aim to keep the centre of the shrub open.
It was a great start to a fresh year of gardening.
To give tree roots a head-start when planting, try adding some mycorrhizal fungi or root builder to the compost.