September Checklist | In Your Garden | The Gardener : The Gardener

September in your garden

This quick September checklist is to remind you what to plant and do in your garden in September.

Spring’s best bloomers

Argyranthemum (daisy bushes) are enjoyed for the profusion of flowers on evergreen shrubs. In our glorious climate they are at their best, and are in bloom with repeated flower flushes from early spring until late autumn if regularly pruned and fed.

The Argyranthemum ‘Madeira’ range of daisy bushes has proved its mettle over the last few years, and will really excite you if you are also daisy crazy. These plants do not grow bigger than 50 x 50cm and form flower-smothered mounds that are perfect for mass or container planting. Colours range from white to dark pink, purplish pink with bright yellow eyes, red and yellow. Flowers can be single, double or densely crested.

There are many ranges that have been bred from our indigenous Cape daisy, Osteospermum ‘FlowerPower’ is still in this year and offers double-crested flowers with double the pleasure, as the blooms don’t close at night. We love the simple single-daisy look of ‘Osticade’ in shades of pink, purple and white. New on the block is ‘Blushing Beauty’, a romantic and exciting bicolour with golden yellow petals with dreamy pink/purple centres.

The plant world is fickle as far as indigenous Nemesia is concerned. As soon as you get to know a new hybrid bred from this lovely genus, which is always flavour of the month in spring, others come along. Most are compact, sweetly scented and will flower repeatedly after a light trim. Nemesia ‘Nesia’ is a top range with shiny green foliage and large, scented flowers in exciting colours. Great for instant bedding colour in sun and light shade.

Dianthus, mini carnations or ‘pinks’, are typical harbingers of spring. Grab a few pots of Dianthus ‘Pink Kisses’ to keep on a sunny windowsill, to plant in window boxes, or as a border for beds. These upright little plants have lovely clove-scented, two-tone pink flowers and light-grey foliage.

Cute combo to try

A bright Pelargonium zonale hybrid teamed up with the tough groundcover Convolvulus sabatius (blue rock bindweed) supplies a typical spring look peeking over a wall. Both are easy to grow in full sun without any pampering.

Lawn tips

Never use garden soil or so-called ‘topsoil’ for top dressing after spring scarifying an existing lawn, as it can cause bad drainage or could be infested with dormant weed seed. Rather invest in sterilised commercial lawn dressing, which will be in stock at garden centres.

Start training your lawn to be water-wise by watering it deeply only once a week – this will encourage deeper root growth.
Never cut your lawn too short as this keeps the roots near the surface where they are more likely to dry out.
For new lawns, start preparing the ground with compost and bonemeal before sowing seed or laying instant turf.
If weeds are a problem in large lawn areas treat them with a broadleaf herbicide. For smaller lawn areas use a ready-to-use broadleaf herbicide.

High alert: Clivias are blooming

Start training your lawn to be water-wise by watering it deeply only once a week – this will encourage deeper root growth.
Never cut your lawn too short as this keeps the roots near the surface where they are more likely to dry out.
For new lawns, start preparing the ground with compost and bonemeal before sowing seed or laying instant turf.
If weeds are a problem in large lawn areas treat them with a broadleaf herbicide. For smaller lawn areas use a ready-to-use broadleaf herbicide.

Heavenly creepers

Plant a deciduous Wisteria sinensis to climb over your pergola. It loves cold climates with winter frosts, it blooms in spring and will supply cool shade in summer.

Gardeners lucky enough to live in the warmer areas should remember to plant Petrea volubilis (purple wreath), a semi-evergreen shrub or creeper that produces sprays of violet-blue flowers in spring.

You will find the very fragrant and evergreen Jasminum polyanthum (white or pink jasmine) in full flower at nurseries in spring. Plant one or more of these evergreen twining climbers, which first produce pink buds in late winter and early spring, soon followed by clusters of sweetly scented, star-shaped white flowers.

High strawberries

Plant your strawberries in hanging baskets and there will be no need to ridge up beds or worry about the fruit rotting on the soil. They will cascade over the edge – fabulous for quick picking, and the flowers are a feature as well. Make sure you fill the basket with a rich, well-draining potting soil and hang it in a sunny spot.

Healthy blueberries

Considering that blueberries have the highest antioxidant content 7 of all fruit, it may well be that they are the healthiest! Blueberries are easy garden shrubs that are generally free of trouble from pests and diseases. They should be planted now in an open sunny position where they will grow to approximately 1.5m in height and have a 1 – 2m spread. They enjoy a moist acidic soil, so ensure that you mulch them well.

A pine-bark-based mulch will provide them with the acidity they love. Regular water and organic feeding will lead to greater yields. Attractive small, white, cup-shaped flowers are followed by delicious bunches of berries that are ready to harvest in midsummer.

Bestest blue

Evolvulus ‘Blue My Mind’ will truly blow your mind with its true-blue, consistent flowering. It is perfect to use as a groundcover in the garden or in containers, where it will form a mounding mat of blue flowers. Its leaves are silvery-green and have a slightly fuzzy feel to them. ‘Blue My Mind’ loves hot weather and will perform best in a full sun position. It is fairly drought tolerant once established, but growth and flowering are better with consistent moisture. As much as it loves the heat, this plant needs to be protected from even light frost.

Magnolia magnificence

A glorious spring-flowering tree is Magnolia x soulangeana. It’s a dainty deciduous tree of about 6 x 6m in size. Out of the characterful main stem sprout many side branches, which produce the most awesome tulip-shaped flowers in shades of pink, dark pink, lilac or white, from late winter to spring. (The flower colour will depend on the variety you plant.) From afar these large flowers, which are produced in great numbers, create the illusion that a great swarm of exotic birds has come to visit the garden. Light green leathery leaves only appear when the flowering period is over. The tree’s summer canopy does not cast deep shade, which allows the gardener to plant lots of annuals, perennials and small shrubs beneath it. It is the perfect tree for a small or cottage-style garden: easy to grow, but slow to grow up.

Sow a merry flower meadow

Get down and dirty with direct sowing to create a meadow or bed filled with the controlled chaos of pretty flowers to wander through, to pick and to enjoy. All you have to do is to prepare the soil well with compost and bonemeal, and to follow the instructions on the back of seed packets for each type of seed. The soil should never dry out after sowing. If necessary, give a light sprinkling of water twice a day.

As soon as germination is completed and the first true leaves show, you can give less water. Sowing in September should include cornflowers, godetias (satin flower), cleomes (spider flowers), sunflowers, love-in-a-mist and zinnias.

Patio strings

Trailing succulents in small hanging bowls are quite fashionable as patio or indoor decoration. Two pretty and peculiar ones to look out for are:

Curio radicans (string-of-bananas, baboon toes): An indigenous succulent groundcover that will cascade lushly over the sides of a container. The leaves are small and spindle-like, with claw-like tips and a translucent strip along the side. They can turn red if exposed to bright sunlight. Minute sweetly scented flower heads appear throughout the year.

Curio rowleyanus (string-of-pearls) is a trailing groundcover native to the drier parts of south-west Africa. It is shallow-rooted and forms dense mats in the shade of other plants or rocks. The leaves are round with a sharp point, resembling small peas, and also have a translucent darker green strip down the side. In summer this off-beat succulent produces tiny white flowers with colourful stamens, which smell like spicy cinnamon.

Keep these plants in bright light indoors, or morning sun and afternoon shade outdoors. Water only when the soil feels dry. As the leaves have a slight toxicity, keep them away from small kids.

Sucking pests

Symptoms of an aphid infestation are the appearance of colonies of aphids on young plant stems, leaves and buds, as well as black sooty mould on leaves and fruit, and yellowing leaves. Plant growth is stunted, leaves eventually die off due to sooty mould fungus, bud growth is prohibited, and the plant will die. Eradicate sucking insects like aphids by spraying with a contact insecticide every two weeks or by a seasonal soil drench with a systemic insecticide.

Arbour week

The first week in September is arbour week, which means we all have to plant a tree for future generations but also for our own pleasure. Nobody’s going to care which tree you have decided to plant – it is up to you. It could be a fruit tree or even an indoor tree, as long as you plant something!

More to do

No need to replace frost-damaged bedding begonias with new plants. Simply cut them back to remove the damaged parts and dose them back to health with a water-soluble fertiliser.

Start spraying fruit trees against fruit fly and codling moth once about 75% of the blossoms have dropped off. Spray every 10 – 14 days.
Divide and re-plant Zantedeschia aethiopica (white arum lily) into boggy areas of the garden – you can never have too many of these veld beauties, which also love to grow on the southern side of the house.
By the end of this month you can prune away the frost-damaged parts of affected plants to tidy them up and encourage new growth. Give them all a feed with a slow-release fertiliser, mulch well with a fresh layer of compost, and water deeply.
With this season’s rapid growth, hedges, topiaries and standards will lose their shape. Don’t allow this to happen: rather clip regularly and lightly than one drastic hack now and again. The best way to keep the shape of flowering standards is to regularly pinch out the growing tips of stems and wait until after each flower flush to give it a good clipping.
Plant charming perennials in your spring garden, like columbines, gauras, carpet geraniums, bearded irises, giant statices and sweet violets.