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September checklist

September is a busy month in the garden calendar. The days are getting longer and the weather warmer. The promise of a long hot summer and a bumper harvest is in the air!

Key points for this month:

  • It's spring and time to prepare your garden for planting
  • Sow vegetable seeds for summer salads
  • ‘Fresh is best’ plant vegetable seedlings
  • Prepare and plant your herb garden
  • Time to refresh and replenish your pots
  • Continue to plant seed potatoes
  • Plant and feed strawberries
  • Plan your garden colour, plant seeds, seedlings and perennials for summer colour
  • Continue to plant trees, shrubs and hedges
  • Planning a new lawn? It’s time to sow seed

Kitchen Garden

If you haven’t already prepared the soil now is the time to get started. If it doesn’t need turning over, then spread a couple of bags of compost over the bare soil and dig through the top layer before you plant.

Empty your compost bin, it is ready when it is the consistency of lumpy soil, don’t plant straight in to it though, it is too rich, leave for a few weeks before planting.

Frost will be you biggest enemy now, be vigilant. Drape frost cloth over but not touching the plants. If it is too close a hard frost will freeze it to the plants.

Sow seeds; carrots, parsnip, beetroot, silverbeet, peas, lettuces, leeks, cabbage, tomato, capsicum, courgette, melon, cucumber and eggplant. Transplant to the garden as the weather warms and when they are showing at least two sets of true leaves. For help on growing from seeds, see our Easy As guide on this here.

Sow peas, snow peas, runner and bush beans, directly in to the ground. Protect from any frosts. Planting seeds too deep can lead to decay. Follow the instructions on the back of the packet.

Don’t waste the little plants you pull out when thinning your carrot and beetroot, they are great in salads.

For the warmer regions plant, eggplant, capsicum, cucumber, melons.

Plant seedlings: Lettuce, leeks, cabbage, corn, pumpkin, celery, onions, silverbeet, courgettes.

Stagger planting green salad crops like mizuna, lettuce and mesclun for continuous supply.

Plant passionfruit early in the warmer regions, they need well drained soil and strong support. Protect the tender foliage from frosts. Check out our Easy As guide on growing passionfruit here.

Continue planting herbs, unless you are in the warmer parts of the country leave basil and coriander until October.

Plant sprouted seed potatoes, or a second crop for a staggered harvest. For advice, see our growing potatoes information here.

Plant new citrus trees; remove the flowers from the young trees, by pinching between your finger and thumb. This will benefit the tree by letting it concentrate on growing before producing. We’ve got more information on this here.

Feed strawberry plants, with strawberry food every two weeks, water in the fertiliser.

Protect all seedlings from slugs and snails, they love tender seedlings.

Garden Colour

Continue replacing your winter flowers with new spring annuals as needed. A pinch of blood & bone as you plant your annuals will give them a head start.

Continue to replant your pots, if the potting soil is old it will be depleted, remove the old soil, add new container mix and fresh new flowers.

Sow seeds: begonias, carnations, cosmos, flowering kale, impatiens, lobelia, salvia, viola, poppies. Transplant to the garden as the weather warms and when they are showing at least two sets of true leaves.

Plant seedlings: ageratum, alyssum, aster, begonia, californian poppy, carnation, cosmos, dahlia, impatiens, marigold, and petunia. Your local Mitre 10 store will stock the full range of spring annuals.

Sow sweet peas for summer colour, they like plenty of sun, well drained soil and trellis support. Try dwarf sweet peas in pots or hanging baskets.

Plant sunflowers either in pots or straight in to the ground in warmer regions.

Feed your hibiscus, they like the same food as citrus.

Plant summer bulbs, gladioli, dahlia, begonias, add bulb food to the soil as you plant.

Plant new perennials, prepare the soil with compost, protect from frost.

September is a good month to plant lavender. They like a well drained position with at least half day sun.

Feed spring flowering bulbs with bulb food as the foliage begins to die off.

Trees and Shrubs

Plant new trees and shrubs dig compost with the soil and add a long term fertiliser to the bottom of the hole.

Plant that hedge, use a long term fertiliser at the bottom of each hole. For easy watering use a soaker hose, lay out along the planting line, move when necessary.

Plant large shade trees, stake firmly at the time of planting.

Choose new camellias and rhododendrons, they like an acidic soil and semi shady position.


For more on growing and caring for lawns see our lawn guide.

Sow new lawn; take advantage of the spring rain and warmth to germinate new seed.

Fertilise your lawn for spring. Apply evenly across the whole lawn and water in.

Spray for onehunga weed, it comes in to flower in September and October now is the time to spray for it.

Attack the broadleaf weeds in the lawn. Wait for a calm day before using any sprays.