September Gardening Tasks

pitchfork digging
strawberries flowers
planting houseplants

September Gardening Tasks

As we head into September, the home garden springs to life with a flurry of activity, rivalling even the bustling days of October that are ahead. The hard work is well worth it because the effort you invest now will result in a thriving, bountiful summer garden!


Veggie garden
Almost all winter vegetables are now ready for the final harvest before the summer garden is planted. Vegetables to be harvested include broccoli, brussel sprouts, cabbage, carrots, cauliflower, celery, kale, leeks, lettuce, parsnips, radishes, silver beet and spinach. 

If you haven’t prepared your soil yet for spring planting, make it a top priority! See our spring garden preparation guide here. 
Toward the end of September in warmer parts of New Zealand, and if spring has arrived early, traditional summer vegetables like courgettes, peppers, tomatoes, and sweetcorn can be planted. Inspect young vegetable plants daily as hungry slugs and snails are particularly active at this time of year.


Potatoes for Christmas 

Preparation is key for a successful potato crop. Choose a north-facing, free-draining site. The rows for the potatoes should be slightly mounded to ensure excess water doesn’t pool around the new plants. If your soil is particularly heavy (clay-based), add some gypsum to break it up along with plenty of compost to improve drainage before planting. Choose seed potatoes (from your local garden centre) of the early variety you wish to grow (read our potato guide for recommendations).Root vegetables need room to grow so plant seed potatoes 5-8cm deep, 20-30cm apart, in rows 70cm apart. When plant growth reaches 20cm, mound the soil up around both sides of the plant weekly or bi-weekly. You can even cover some of the new shoots and lower leaves as this helps towards a better crop. ‘Mounding up’ warms the soil so plants grow faster, helps protect against frost and prevents the greening of your young potatoes as they form. 


Flowering annuals
Winter flowering annuals like cineraria and primulas are now finishing their flowering. Some annuals that can be grown regardless of the season include alyssum, cornflower, lobelia, nemesias, and violas. 
Towards the end of September classic summer annuals can be planted including asters, livingstone daisy, marigolds, petunias, salvias and zinnias. As with the vegetable garden, prepare new sites thoroughly by adding fresh compost to the existing soil. 
Flowering annuals can also be planted in containers of various sizes. Be sure to use a potting or container mix which are designed specifically for container growing. Do not use compost.


Fruit Trees
Numerous citrus trees are still covered with delicious fruit. Navel oranges are now at their sweetest, as are grapefruit. Lemons and limes are nearing the end of their fruiting season. Citrus Ugli Fruit that looks and tastes like a large navel orange is now ripening. Many citrus trees will begin flowering towards the end of September, so no spraying at this time.


Strawberry plants will be in active growth in September and may commence flowering. As tempting as it is to keep them, it is best to remove any young flowers until early October as fruit formed before this date will be of poor size and taste. Top up the soil around the young strawberry plants with fresh compost and ensure you have a good layer of mulch for the coming fruit to ripen on.


Winter and spring flowering bulbs growing in permanent positions can be left to naturalise – this means leaving them to self-seed and propagate themselves naturally. These include crocus, freesias, hyacinths, iris, lachenalia, muscari, narcissus and watsonias. Tulips are not suitable for naturalising in warm northern areas and can fail to flower in the second year due to a lack of winter chilling. It is best to lift them and replant them next season.


Enjoy the first gorgeous blooms of rose bushes before the challenges of black spot and rust set in typically around late Spring and Summer. 
For vibrant flowers and healthy green leaves, apply Daltons Premium Rose Fertiliser at six weekly intervals. Spread fresh Garden Time Compost around all roses at regular intervals throughout summer. With climbing roses, tie up the main leaders (canes) to prevent wind damage.


Grass growth is increasing as temperatures rise. Mow regularly, slowly lowering the level of the mower over the month. Apply Premium Lawn Fertiliser two to three times in spring and water it well afterwards. With warmer temperatures, it’s also a good time to tackle any lawn brown patches or issues.


Continue to re-pot any houseplants that have outgrown their containers or need a fresh mix. 
Check the position of your houseplants, especially those growing near windows. Cyclamen can now be put outside in a shady position for next winter. Premium Houseplant Fertiliser or Planter Tabs can be applied to most houseplants in small quantities. It’s also time to feed orchids – try our Premium Orchid Food which is applied as a liquid feed.  The amount of watering required can be increased as temperatures rise. Remember to regularly ‘mist’ your foliage houseplants with lukewarm water.

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