PLANT YOUR BORDER
STEP 3
If you’re after a tip-top display you really want to spoil this planting. Give it your best, sunniest site sheltered from strong winds and be prepared to seriously improve your soil to ensure fertile growing conditions. Annual mulching with well-rotted organic matter as well as digging in further material at every planting will also help. Be prepared to water deeply during prolonged dry spells.
1 Order the dahlia & canna
Order dahlia tubers and canna rhizomes now from an online specialist and they’ll arrive in the post next February or March. Be sure tubers/rhizomes bought from a garden centre look healthy and disease free. Pot up and grow on in a frost-free greenhouse. Only lightly cover cannas with compost. To increase dahlia stocks, take cuttings from the new shoots. Plant out in late May, watching out for slugs and snails, which can decimate young foliage. Give cannas lots of extra compost since they’re greedy feeders. Although ‘Fascination’ is quite a short dahlia, put in a cane when planting so you can support with twine if needed. Deadhead every time you pass to keep the display coming. After the first frosts, cut plants back then lift and store tubers/rhizomes in barely damp old potting compost in a frost-free shed. You can leave them in free-draining soil in sheltered spots covered with a protective dry mulch.
2 Sow the verbena
Verbena bonariensis is a doddle to grow from seed, as long as it has an early start. Sow in March on a warm windowsill or heated propagator around 20C (68F), or you can buy young plants in late spring. Once established, self-sown seedlings will pop up in paving cracks or gravel. These short-lived perennials overwinter best on well-drained soil with a dry mulch. Don’t cut back top growth until new shoots appear in spring.
3 Sow the Spanish flag
Sow seeds mid-April to May, one per pot in a propagator to maintain a cosy temperature (around 21C/70F). Pot on before planting out in early June when nights should have warmed up. These plants cope with shade as well as sunshine, just avoid too much nitrogen in the planting site or you’ll run the risk of over enthusiastic foliage with little in the way of flowers. They’re brilliant at rambling right through a planting, often travelling in unexpected directions.
4 Add the pennisetum
‘Rubrum’ is sterile so you’ll have to order plants from a specialist nursery or buy from your local garden centre. Plant out youngsters after all risk of frost. Position at the front of the border so you can stroke its arching bottle-brush flowers as you pass. Dig up plants once frosts threaten and move into a frost-free greenhouse or porch. Lift as a single large clump, cut back top growth by half and place in a large container, filling any gaps with old potting compost. Water sparingly over winter then divide into smaller clumps and pot up in fresh compost ready to go out in late May.
5 Establish the tetrapanax
Specialist nurseries are your best chance of finding a young tetrapanax. Plant in a well-drained site in early June, giving it plenty of space, and further improve the ground with well-rotted organic matter. Severe winters will dictate how much top growth survives. Even if it’s cut back right to the ground by frost it regrows from its roots the following year. You can also coppice plants right back in early spring to encourage lots of low shrubby growth rather than a taller trunk. Remove and pot up suckers as they appear.