In the Garden | Dahlias and passionfruit

Grown by 16th century Aztecs as medicinal plants and attractive flowers, they were eventually brought to Europe in 1789 and named after the Swedish botanist professor Andreas Dahl.

Over the years, the original, rather small but decorative blooms developed double forms which in turn were hybridized by enthusiasts around the world offering descriptive names such as decorative, pompon, collarette, cactus, waterlily and others.

Whether tubers are passed on by friends, purchased from nursery shelves or a specialist grower, each should contain an ‘eye’ or potential shoot before they will produce a new stem and bloom. Large containers as well as in-ground beds are both appropriate planting sites provided they are weed free and enriched with organic matter. Additional fertiliser is not necessary until the plants are well grown and beginning to produce buds.

Tall growing plants will need to be staked for stems are brittle and easily damaged by the wind. Encourge side growth to offer more bloom by ’stopping’ or pinching out a tip growth once it has reached the three to four leaf stage.

In well drained soils of a cool climate garden, mature tubers can be left over winter to grow on and flower again next season. However, in heavier ground that remains wet over winter, tubers are best lifted to avoid rotting; put into storage then replant the following year.

While summer soil moisture is essential to maintain plant structure, at any time of year minimal overhead watering will reduce the incidence of fungal diseases such as powdery mildew.

October is also the time to sow Cosmos, pretty flowers in white, rose or crimson with a great attraction for bees. Growing to around a metre tall the feathery foliage makes a great back ground to other summer blooms. 

Yates Thrive Flower and Fruit soluble fertiliser has added potassium to encourage flowering.

The purple-fruited passion vine from Southern Brazil makes an attractive semi-evergreen creeper. In a protected site in a cool climate it will provide a quick cover for a bare, but heat retentive, brick wall while yielding a crop of aromatic pulpy fruit.

While the grafted ’Nellie Kelly’ has proven to carry the strongest and most prolific crops, they are comparatively short lived. Eventual woodiness of the fruit means they should be replaced every five to six years. Be sure to use a complete fertiliser throughout the growing season. A lack of potash is the cause of poor pollination and early fruit drop. Vines will need additional feeds and an organic mulch to keep the roots cool and moisture levels up during the summer. Vigorously growing plants will not only produce more flowering shoots but maintain good health.