Thinning

Sunday, 08 June 2014

Agapanthus clump in need of division

This long weekend I am doing some much-needed thinning out of congested plants. It's not a task I tend to get round to very often, but I am giving some clumps to someone who is starting a garden from scratch so this seemed to be the perfect opportunity to improve the wellbeing of my own plants without having to throw out a lot of plant material. This is a great time of year to tackle the task as plants will survive the ordeal much better in cooler months.

It's so easy to forget about those tough clump-forming plants that just gradually increase in girth year by year, usually via rhizome-like roots. It is quite startling when you realise they have actually filled in a square metre of space and are probably facing a lot of competition now for water, nutrients and even soil to grow in! Flowering begins to be affected when clumps get too overgrown. When I started my garden 20 years ago, there was basically nothing in it and I was so envious of other people's established gardens, so it still seems surprising to me that I now have significant clumps of plants that I can pass on to other gardeners to fill their gaps.

Phormium growing in paving with crowded dwarf Agapanthus around it

Thinning out plants is a concept that has application to all levels of the garden - from a batch of tiny seedlings in a punnet to a border and to a thicket of trees. All plants do need space around them to do their best. Whilst it is heart rendering to thin out seedlings, the ones that are left will thrive much better for not having so much competition. Plants in borders can actually be killed when overgrown or swamped by vigorous companions nearby. I find it very hard to space plants properly when first planting out a new border, thus much tinkering is required to get the balance right over time. Some plants particularly need space around them to show off their form - for example, grasses and other arching plants such as Phormium and taller members of the Iridaceae family. I grow some of these plants in square beds in paving in front of the house, where they aren't crowded out by other plants.

This very thick clump of Clivia is going to be divided

The main clumps I am planning to divide up include huge swathes of Clivia and Agapanthus. These are wonderfully undemanding plants that give welcome greenery all year round plus long-lasting flowers in their individual seasons: the Clivia in late winter/early spring and the Agapanthus in late spring/early summer. I have yellow, pale orange and brilliant red/orange Clivia and a few different sorts of Agapanthus, including some named bright blue/purple ones and a miniature form: all in need of urgent division.

Mondo grass growing around Dietes robinsoniana is very congested

Other clumping plants I have my eye on are the mondo grass I have in the garden and various types of Liriope, including the giant one. These plants are evergreen and give a lovely linear texture in gardens, with the bonus of coping with shade. Aspidistra is another clump that has grown to enormous proportions and I will be digging some of it up too. Its lance shaped leaves provide year-round form and it grows in dry, inhospitable places where few other plants will survive. There are a few variegated forms that also do well in our climate.

These bromeliads need to be thinned out

I am also going to pull up a range of bromeliads, as these too can stealthily cover much ground. There is such an array of colours in the leaves and flowers of these shade-loving plants and they need basically no attention during the year. They can provide an instant effect in a new garden if grouped together.

All these plants can contribute to the evergreen backbone of a garden, along with evergreen shrubs to give permanent form - something I am craving more and more these days. Most of them came from my parents' garden in the Blue Mountains. It's good to be able to pass plants along, and my plants that remain will benefit from the reduced congestion. The exchange of plants amongst friends is one of the most appealing aspects of gardening, and many plants in my garden are living reminders of the people who gave them to me.