Last week I visited a garden that used standardised plants most effectively to add rhythmic formal structure to its design. Training plants to a single trunk and clipping the foliage into a rounded or domed shape is a good way to give height in a garden without taking up too much space at ground level, especially in narrow areas. The area around the trunk can often be planted up with low-growing specimens. A standardised plant is often a good alternative to an overly heavy shrub blocking out light to surrounding areas of the garden and limiting other plantings. A row of standard plants can be used to divide sections of the garden, and single specimens can provide a strong form to contrast with more billowing plantings below it. Small standardised specimens are ideal for creating a touch of formality in courtyards and on balconies, or on either side of a front door or a seat.
The best plants to use are bushy types with fairly compact foliage - some examples suitable for Sydney gardens include Japanese box (Buxus microphylla var. japonica), cumquats, lilly pilly (Syzygium species), bay tree (Laurus nobilis), rosemary (Rosmarinus officinalis) and Murraya paniculata. Some flowering plants are also suitable, providing a lovely spectacle when in bloom: Camellia varieties, Gardenia florida, Rhaphiolepis indica, Heliotropium arborescens and Fuchsia cultivars. Some trees can also be trained as standards, such as the ornamental cherry, maples and the mop-top Robinia 'Umbraculifera'. These are usually grafted.
I have found that standardising a plant can be a way of controlling shrubs that otherwise can grow in a rather unruly fashion, taking up too much space and looking untidy. I have a specimen of Solanum rantonnetii trained (by a friend) to a single trunk and it is a much better-behaved plant grown this way than allowed to grow as an unfettered shrub (though does require a fair amount of clipping!). Similarly, I have contained Buddleja 'Spring Promise' to grow as a standard: it now takes up a lot less space at ground level, allowing other plants to grow nearby.
I once saw a wonderful specimen of Abutilon megapotamicum grown as a weeping standard - a good way of taming this rather lax and rambling shrub. Weeping standards can provide a gorgeous feature, but they usually need a strong circular sustain of some kind to bear the weight of the top growth. Some plants grown in this way are actually climbers - such as Wisteria cultivars, climbing roses, honeysuckles (Lonicera species), Bouganvillea cultivars and Stephanotis floribunda.
Standardised plants can be expensive to buy, but you can train your own shrubs or climbers if you have the patience. It is best to start with a plant that has a nice straight tall stem. Give the stem support with a strong stake. Strong lateral shoots along this stem should be removed, but weaker laterals should be just shortened in the early stages of the development of the plant, so that their foliage can help the plant manufacture food to build the strong central stem. Once the central stem has reached the desired height, allow three more sets of leaf buds to develop then pinch out the growing tip. This allows growth of shoots from the lateral buds below to form the main framework of the head of the standard plant. These laterals can be regularly tip-pruned - and then shortened by half after the first growing season. Once established, prune it to shape regularly. At this stage, any shoots that develop on the trunk can be removed.
Standardised plants grown in the garden need the usual fertilising and watering as other shrubs; those grown in pots need extra care to make sure they remain looking at their best.
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These plants bloom for many months in my garden - and some are in flower all year!
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Many scented flowers are in bloom now.