Proper Pruning
Salvias play a major role in this planting, and essential to their success is
pruning. Left on its own, the fall-flowering forsythia sage may reach 8 feet in
height. By cutting back the plant by half in midsummer, Mary keeps it 4 to 5
feet tall with numerous spikes of flowers. Other plants in the border are also
managed this way, including Mexican bush sage (Salvia leucantha) and Tatarian
aster (Aster tataricus). Salvias in the border that do not require pruning are
'Lady in Red,' 'Indigo Spires,' and pineapple sage (S. elegans).
Supports for Growth
Another technique for a full fall bloom is to support these tall-growing plants
so they stand upright. Plastic-coated metal grids are placed over the young
plants in late spring and early summer. Rather than trying to stake plants after
it is too late and risk breaking stems, Mary supports them as they grow. These
grids are available at many garden centers and through mail-order companies.
Plants that benefit from this care include the salvias, garden phlox, pink
boltonia (Boltonia asteroides 'Pink Beauty'), switch grass (Panicum virgatum'Heavy Metal') and yellow shining coneflower (Rudbeckia nitida'Herbstsonne').
Tricks of the Trade
At 120 feet long, this border is relatively narrow--only 4 feet. Mary compensates
by taking space from behind the fence. 'Callaway' crabapple trees with their
bounty of red fruit echo the colors of the border and give the illusion of
depth. Any garden that has a long season of bloom has foliage from
perennials that have already finished flowering--daylilies, iris, and such.
However, Mary sees the leaves as assets. They are full, green, and offer
vertical form and interest. There are also plants grown strictly for their
ornamental foliage--grasses, sweet potatoes, Caribbean copper plant (Euphorbia cotinifolia), and coleus.
The stone walk that separates the border from the lawn becomes less of a
path as the garden spills onto it. Still, it is probably best to step back and
view the border from the lawn. It's almost more than you can absorb at a single
glance.
With the help of Mary's tips and favorite plant combinations, you can savor
a lush fall border in your garden too.
Cutting Them Back
The key to managing many tall, fall-flowering annuals and perennials (whether
they come back in spring or not depends on where you live) is midsummer pruning.
If left unpruned, they may flop from their extreme height or get out of scale
with the rest of your border. Simply cut the plants back to half their height,
whatever that is. They will branch, be fuller in bloom, and flower somewhat
later. The results are worth the wait. Mary Zahl encourages her clients to prune on Bastille Day, July 14th. It's a naughty, but
handy way to remember. Plants that benefit from a trim in midsummer include the
following.
- Tatarian aster (Aster tataricus)
- Boltonia (Boltonia asteroides)
- Joe-pye weed (Eupatorium purpureum)
- Swamp sunflower (Helianthus angustifolius)
- Mexican bush sage (Salvia leucantha)
- Forsythia sage (S. madrensis)
Then there is another group of perennials that bloom earlier, but if the spent
flowers are removed and plants cut back by about one-third, they will bloom
again in the fall.
- Carolina phlox (Phlox maculata 'Miss Lingard')
- Garden phlox (P. paniculata 'David' and 'Robert Poore')
- Orange coneflower (Rudbeckia fulgida)
- Shining coneflower (R. nitida 'Herbstsonne')
