Care guides › Brisbane › September

September in the Brisbane garden

Early spring in Brisbane. Subtropical: no frost, a dry spring, then a wet summer. Here is what needs doing this month, with the essentials first.

What to plant 13
What to harvest 21
Feeding 7
Pruning and deadheading 10
Watering 11
Seasol and tonics 1
Mulching 2
Pests and diseases to watch for 3
Frost and weather 1
Tidying up 6

What to plant in September

Tomato, Capsicum and Eggplant

Plant out once the soil is warm
Cucumber and Zucchini

Sow or plant once the soil is warm
Sunflower and Cosmos

Sow seed direct once the soil is warm
Carrot

Sow seed direct every few weeks
Runner Bean

Sow at the base of a tall support
Leek

Plant seedlings deep to blanch the stems
Sweetcorn

Sow in blocks, not rows, so it pollinates
Dahlia

Plant tubers once the soil warms
Marigold

Plant seedlings once the soil is warm
Basil

Plant once nights are warm
Dill

Sow seed direct; it dislikes being moved
Silverbeet

Sow or plant seedlings
Warrigal Greens

Sow soaked seed or plant out in spring

What to harvest in September

Carrot

Pull from about 12 weeks after sowing
Broad Bean

Pick pods while the beans are bright green
Pea

Pick pods as they fill
Spinach

Pick outer leaves
Kale

Pick lower leaves; cool weather sweetens them
Broccoli

Cut the head while buds are tight; side shoots follow
Cauliflower

Cut while the curd is firm and white
Cabbage

Cut when the head feels firm
Orange Tree

Pick when sweet; taste one to check
Lemon Tree

Pick lemons as they colour; they hold on the tree
Cumquat

Pick when fully orange
Asparagus

Cut spears at ground level (from the third year)
Artichoke

Cut buds while the scales are tight
Silverbeet

Pick outer leaves as needed
Warrigal Greens

Pick the soft tips often; blanch before eating
Lemon Myrtle

Pick leaves as you need them; they dry well
Sweet Pea If you have time

Pick flowers often: the more you pick, the more you get
Rosemary If you have time

Snip sprigs as needed; it keeps it bushy
Thyme If you have time

Snip sprigs as needed
Chives If you have time

Snip leaves to 5 cm; the flowers are edible too
Coriander If you have time

Pick leaves young; let a few go to seed

Feeding

Natives

Slow-release native fertiliser (low phosphorus), once a year; never ordinary fertiliser
Shrubs and perennials

Slow-release fertiliser in spring and early autumn
Summer vegetables

Dig in compost before planting
Blueberry Bush

Azalea and camellia (acid) fertiliser
Cool-season vegetables If you have time

Liquid feed every 2-3 weeks while growing
Herbs If you have time

A little liquid feed in spring and midsummer
Rock Orchid If you have time

Weak orchid feed every few weeks while growing

Pruning and deadheading

Sage

Cut back by a third as new growth starts
Orange Tree and Mandarin If you have time

Light prune after harvest to open the canopy
Tomato If you have time

Pinch out side shoots and tie the stem to its stake
Broad Bean If you have time

Pinch out the tips once pods set (deters aphids)
Banksia If you have time

Light prune after flowering; never cut into bare wood
Bougainvillea If you have time

Prune after each flush of flowers
Passionfruit If you have time

Light prune to tidy and let light in
Sasanqua Camellia If you have time

Shape or hedge after flowering
Olive Tree If you have time

Thin the canopy to let light in
Geranium If you have time

Snap off spent flower heads

Watering

Natives

Established plants: only in a heatwave or after 3 weeks without rain, then a deep soak
Shrubs and perennials

Deep soak weekly in dry spells
Azaleas, camellias and other acid-lovers

Shallow roots: deep soak weekly in dry spells
Citrus

Deep soak weekly, more while fruit is setting
Fruit

Deep soak weekly in dry spells, more as fruit swells
Summer vegetables

Deep water 2-3 times a week; uneven watering splits fruit
Herbs and annual flowers

Water when the top few cm are dry
Red Flowering Gum and Red Flowering Gum (Dwarf)

Young trees: deep soak weekly in summer for the first two years
Hydrangea

Thirsty: water deeply in heat, it wilts first
Japanese Maple

Keep moist and shelter from hot wind: the leaves scorch
Cool-season vegetables If you have time

Keep evenly moist; water when the top few cm are dry

Seasol and tonics

Natives, shrubs and perennials, azaleas, camellias and other acid-lovers, citrus and fruit If you have time

Seaweed tonic (e.g. Seasol) in spring and autumn, and after a heatwave

Mulching

Summer vegetables If you have time

Straw or sugarcane mulch once the soil has warmed
Strawberry If you have time

Straw under the plants keeps fruit clean

Pests and diseases to watch for

Kale, Broccoli, Cauliflower and Cabbage If you have time

Cabbage white caterpillars: check under the leaves, squash eggs and grubs, or net the crop
Kangaroo Paw If you have time

Snails: check new growth at dusk after rain; pick off, or scatter pet-safe iron pellets
Azalea If you have time

Petal blight: pick off brown, mushy flowers; spray lace bug under leaves with horticultural oil

Frost and weather

Peony If you have time

Ring-stake before the buds get heavy

Tidying up

Chives and Liriope If you have time

Divide crowded clumps
Potato If you have time

Mound soil over the stems as they grow
Sunflower If you have time

Stake tall stems before they flop
Clematis If you have time

Tie in new shoots as they grow
Creeping Boobialla If you have time

Pull weeds out of the mat before they seed
Fan Flower If you have time

Pinch the tips to keep it dense

Not listed: Cherry Tree, Blackcurrant Bush, Gooseberry Bush, Rhubarb, Blue Leschenaultia, Boronia and Common Heath, which don't suit Brisbane's climate.