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.

Reader Comments

  • By Chris 2071 Monday, 09 June 2014

    Do you grow the different colours of Clivea together,or in the same bed, or do you separate the yellows and oranges, say, in different parts of the garden? Do the colours mix effectively? Chris I do have the different colours in different areas. The orange ones are with abutilons (orange and red) and Scadoxus puniceus (bright red/orange in late winter) whereas the yellow ones are with a blue salvia that flowers in late winter and I have other yellows next to yellow abutilions and variegated yellow-leaf shrubs. Deirdre

  • By margaret 2122 Monday, 09 June 2014

    Plants in my garden also need dividing, including clivia, liriope, some rhizomatous begonias, and an especially large clump of two varieties of aspidistra, so your article has spurred me into action - thank you. In answer to Patricia, I separated a large clump of yellow clivia, this time last year, and they flowered really well in spring. I did the same with my white haemanthus, with no detrimental affect. Thanks for that reassurance on the clivias, Margaret! I am enjoying your white haemanthus flowering at the moment. Deirdre

  • By Chris 4034 Monday, 09 June 2014

    Good idea Diedre , My white agapanthus has a large root system and need more space around them. My orange Clivea has not flowered yet, so I might look at dividing it and moving it to another site. Bromeliads are good to put in most spaces as they do not seem to have a large root system, and they keep humidity in an area. Gardening is learning, I feel we learn everyday especially with your help, Thanks . Having now done the agapanthus and clivias this morning, I was stunned at how congested the roots were and felt ashamed that it took me so long to divide them! Deirdre

  • By Maureen 2118 Monday, 09 June 2014

    Looks like we are all thinking along the same lines - especially re my agapanthus which are somewhat overcrowded and U had very few flowers last year. Thanks Deirdre for putting our Sunday meeting at the RHS with Ross Bolwell on the events site too. Cheers. Thanks, Maureen. I am so pleased I have done the dividing and the excess plants will be going to a good home. Deirdre

  • By Richard 2112 Monday, 09 June 2014

    Clivias, are almost indestructible so long as not too damp or in too much sun. I dug up 2 large clumps of Belgian Hybrids last September; I divided 1 and replanted, & they all took including those planted with virtually no roots attached. The other clump is still sitting out of the soil looking as healthy as always, & should flower in this state. For yellow, cream, red & pastel Clivias at bargain prices, try Victoria Garden at 1007 Old Northern Rd Dural during the flowering season (September) Thanks for those great tips, Richard. I would like to visit that clivia nursery some time. Deirdre

  • By Helen 7256 Thursday, 12 June 2014

    Do you know if Clivia will grow (and flower well) in cooler climates? I have a frost free garden on King island - summers are mild with average summer days of max 19-25 and winters not very cold with day time temperatures 10 - 15 degrees and minimums generally above 5 degrees . I do have Dracena fragrans growing well in my garden in a very sheltered position.Hi Helen, I think it might be worth a try. Grow them in a sheltered spot under a tree, as they like shade in any case. They are great for late winter-esrly spring colour or in pots (which could be another option for you). Deirdre

  • By Marinka 2041 Saturday, 14 June 2014

    My neighbour kindly passed on a generous amount of cliveas & bromeliads to me in May last year to fill in a new bed I"d created under a tree. The bromeliads flowered within weeks of being planted & the cliveas also flowered in late winter. Perfect instant garden for free! I can also recommend dividing salvia leucantha pretty much any time & it will flower the following autumn without fail - another great instant space filler & super hardy, too! Great to hear all that, Marinka. These plants are all wonderful for helping create new garden areas. Deirdre

  • By Trudi 4223 Saturday, 21 June 2014

    This winter I am radically cleaning out and dividing plants, especially many bromeliads. I have also divided and bought some new daylilies. I easily forget how much better the garden looks if it is not so congested with plants. Many native ferns too had it much too good! A few month ago I have started to plant a new butterfly garden, mainly from cuttings plus a few new addition and also my new love of cottage gladioli. It is a good time of year to reevaluate the garden. Thinning out really does benefit the plants and makes the garden look better. Your butterfly garden sounds a delight. Deirdre

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