As I write this on Tuesday 29th Nov. the forecasters are predicting -3ºC at 0600 tomorrow in Brockwell Park. That’s colder than anything we had last winter. With this in prospect I wrapped one of the stems of the sikkimensis on Sunday as well as the crown of one of the Beshornarias. In conditions like these the surface temperature of the plant stems fall below 0º and frost forms on them. For a Hot! border this is a test but we’ve already mulched the tender varieties with a 15cm covering. What will suffer is the top growth.

We’ll probably have to take down the Colocasia, the Cannas and the Dahlias, leaving them tucked up under their mulch. Almost certainly the Ensetes will be stopped in their tracks but we can probably leave them until the spring. If the Ricinus survive we’ll need to de-seed them. The Tithonias need to come out. We’ve saved seed from the Ricinus and the Tithonias. We’ve also saved one or two viviparous plantlets from the Hedychium greenii. Actually, this is not a lot of work to do which is good because I want to spend at least an hour in the greenhouse talking about the borders that you are planning.

Form, Texture and Colour

For this session we’re interested in those plants form, texture and colour and with what other plants might go alongside, in front or behind. Managing form and texture will have a big impact on the look of your border.

Form is is what is seen when first looking at a border from a distance. Every plant has a distinct habit, a unique shape and size which develops and changes as the plant matures. These shapes divide and define the spaces in the border. Some forms are more dramatic than others and so attract attention. The site of a specific plant may block a view, or open a sight-line, or alter the view. The form of the plants selected and their placement are critical to creating dynamic spaces and pleasing lines.

Thinking bout the Hot! border the first impression is of height and this is achieved with plants that have very distinctive forms. The bananas, bamboo, the giant reed and the castor oil plants all get to 2.5m+ but with completely different forms. None of these has been planted for their flowers – our interest is the impact of their form, texture and colour of the border as a whole. The rice paper paper plants and the fountain grass are also intended as structural components. Even the Canna ‘Purpurea’ are there more for its form than floral interest. These plants give structure and shape to the border They’ve been selected for their form, texture and overall colour.

Looking at the border as it is in August you can also see the value of repetition. The border uses repeated motifs – both species and shapes to give coherence to the border as a whole. Most obviously the two bananas on either side of the path to the shelter. These unify the two sides of the border and suggest that the two beds are both part of the same composition and should be regarded as a whole. There’s repetition too at the other ends of the beds with two large block of Cannas holding either end. The diagonal line tending toward the shelter on both sides is also a repeated motif using plants of all scales. The displacement of these diagonals help to give the border dynamism and a sense of movement.

Looking at a completely different style of border see how form and repetition are used by Piet Oudolf in his design for New York’s HighLine.

The Black eyed susan’s repeated every 15 metres or so draw the eye forward. In narrow sections of this 2km long elevated ex railway line park its important to keep the planting flowing forward. They rise above the massed Senecios and two grasses punctuating the border with their lax free-flowing form.

Ina wider section of the park the stooled Eucalyptus erupt from the mainly clumping species below again providing punctuation as the planting below subtly changes their form and colour providing dimension to the border and introducing the more wooded section beyond.

In Oudolf’s design world he is also planning for the forms of the plants when they’re dead. Here dramatic seed heads climb out of the already browned grass flower heads. These grases should continue to look good until February when they’ll be cut down to ground level only to shoot again in March.

In a more traditional herbaceous border you can also see the use of repetition. Here the sure hand of Gertrude Jekyll punctuates the border with dark red hollyhocks.

This example also illustrates the importance of texture. The holly hock have quite large leaves but these don’t predominate when planting amongst species with more filigrenous leaves. Managing texture is about managing the close view of the border. If you plant lots of coarse plants together you tend to foreshorten the view and the space will appear smaller. In a border with less than 2m depth it advisable to have sections of planting that allow the viewer to see ‘through’ the planting as this adds depth.

In the Hot! border you can see a very wide variety of textures and leaf shapes from the highly serrated Melianthus through the ‘elephants ears’ Taro to the 2m paddles of the red banana. The change of texture through the border coupled with the diagonal drifts creates movement and rhythm

Just a reminder of how the planning is done here’s a small section of the HighLine as a working drawing from Oudolf’s workshop