September Gardening Tips NZ
Spring has arrived! After the shorter days and colder weather of winter, September brings noticeably longer days, warmer temperatures and plenty of new growth. Spring bulbs are flowering, deciduous trees are beginning to burst into bloom, and the garden is starting to come alive again. September is arguably one of the most important months in the New Zealand gardening calendar because it marks the beginning of the main growing season. This is the time to get your garden ready for the months ahead and, in most parts of New Zealand, begin planting your main-season crops. However, don’t get too carried away by the warmer weather. Late frosts are still a possibility in many areas, so frost-sensitive plants may need protection until the danger has passed.
Here are my September gardening tips for NZ to help you make the most of the start of spring.
September Gardening Tasks
General September Gardening Tips
By September, you should have a good idea of what you want to achieve in your garden over the coming growing season. Spring is a good time to put those plans into action, but it is also worth thinking beyond the immediate season. When planting trees, shrubs and other permanent plants, consider how large they will eventually become and whether they will still be in the right position 10 or 20 years from now. A common gardening mistake is planting something in the wrong location and then discovering several years later that it has become too large, is blocking sunlight, damaging structures or simply doesn’t work with the rest of the garden. Removing a mature tree or large shrub can be expensive and sometimes difficult, so a little planning now can save a lot of work later. If you’re planning a major landscaping project, September can also be a good time to talk to a professional landscape designer or contractor. Getting expert advice before starting a major project can help prevent costly mistakes and ensure the garden works well both now and in the future.
Snail and Slug Control
Snails and slugs can become a major problem as spring arrives. Their populations can build up during the wetter winter months, and the combination of increasing temperatures and new soft plant growth provides them with plenty of food. Start checking your garden regularly and put control measures in place before numbers become too high. Take particular care when choosing snail and slug baits. Some products can be harmful to birds, hedgehogs, dogs and other animals if they eat the bait directly or consume dying snails and slugs. Where possible, choose products that are designed to be safer around pets and wildlife. If you use a product that may be harmful to animals, follow the label instructions carefully and place the bait where pets and other animals cannot access it.
Ant Control
If ants have been a problem around your home or garden in previous years, September is a good time to start controlling them before populations build up. Ant baits can be placed in sheltered locations where they will remain dry and where children and pets cannot reach them. Early control can be much easier than trying to deal with a large colony later in the season.
Pruning in September
Most deciduous tree pruning should have been completed by September. If you still have major pruning work to do, check the requirements of the particular tree before proceeding. Different plants have different pruning requirements, and pruning at the wrong time can affect flowering, fruit production or new growth.
Planting in September
September is an excellent month for planting trees, shrubs, perennials and many other plants. Trees, shrubs and perennials planted early in spring have plenty of time to establish their root systems before the hotter and potentially drier weather arrives. Make sure newly planted plants receive adequate water while they establish, particularly if spring turns out to be dry. If you are planting larger trees or shrubs, remember to allow enough room for their mature size. A small plant in a garden centre can become a very large plant in just a few years.
Food Gardening in September
Vegetable Gardening Tips NZ
September is one of the busiest months of the year for vegetable gardeners. Before planting your main-season crops, clear away old vegetable plants that are no longer productive or that are beginning to run to seed. If you want to collect seed from a particular plant, leave it in place; otherwise, removing it can free up valuable space for new crops. Be aware that different varieties of the same vegetable can cross-pollinate. This can be particularly noticeable when allowing plants such as parsley and other herbs to self-seed. Prepare your vegetable beds by removing weeds and adding compost and suitable fertiliser. Organic fertilisers such as well-rotted animal manure and compost can be excellent additions to the soil. If you use a no-dig gardening system, September is also a good time to add compost and other suitable organic matter to the surface of your beds. If you prefer to dig your vegetable beds, work compost and fertiliser into the main root zone while preparing the soil. If you have trees growing near your vegetable garden, keep an eye on their roots. Tree roots can spread surprisingly far and may eventually take over a vegetable bed, competing with your crops for water and nutrients. Dealing with small invading roots early is much easier than trying to remove a large mass of established roots later.
Check Your Soil pH
September is a useful time to test the pH of your vegetable garden soil. If your soil requires lime, applying it before the main planting season gives it time to begin working into the soil. Don’t add lime simply because it is commonly recommended; test the soil first and apply it only where it is appropriate. Good soil preparation at the beginning of spring can make a noticeable difference to plant growth throughout the season.
Start Planting Your Main Vegetable Crops
Once your soil is prepared, you can begin planting many of your main-season vegetable crops. If you live in an area that regularly experiences late frosts, take extra care with frost-sensitive plants. Young seedlings can be damaged or killed by a sudden cold snap even when the daytime temperatures feel quite warm. Cloches, frost cloth and other plant coverings can provide useful protection. In some situations, even a clear plastic container with suitable ventilation can provide temporary protection for a young plant, provided it is removed or ventilated when temperatures rise. Don’t leave plants enclosed in plastic in warm sunshine, as temperatures inside can rise rapidly.
Seedlings or Seeds?
I often like to start the vegetable planting season with punnets of young seedlings. Buying or raising seedlings gives you a head start because the plants have already germinated and established themselves. This can potentially put you several weeks ahead of crops grown from seed. Later in the season, make successive sowings of seeds as earlier crops are harvested. This helps provide a continuous supply of vegetables rather than having everything ready to harvest at the same time. Depending on the vegetable and how much you want to grow, successive sowings every two to four weeks can work well. Direct sowing also has advantages. Plants grown from seed directly in the garden avoid the transplanting shock that can occur when seedlings are moved, and they can develop strong root systems in their permanent growing position. One of the most common mistakes when sowing seeds is sowing them too close together. It can seem sensible to sow lots of seeds because not every seed will germinate, but overcrowding can create extra work later when the seedlings need to be thinned. When sowing, consider the mature size of the plant and leave enough space between seeds or rows. You can always thin out excess seedlings later if necessary.
Vegetables to Plant or Sow in September
Depending on your location and local growing conditions, September is a good time to plant or sow many vegetables, including:
Beans, both climbing and dwarf varieties, beetroot, cabbage, cape gooseberry, capsicum, carrots, celery, chicory, Chinese cabbage, choko, cress, eggplant, endive, kohlrabi, leeks, lettuce, peas, marrows, melons, mustard, spring onions, parsnips, potatoes, radishes, rhubarb, salsify, silver beet, squash, spinach, swedes and turnips.
Remember that New Zealand has a wide range of climates. What can be planted outdoors in a warm northern garden may still need protection in a colder southern or inland area.
Herb Gardening Tips NZ
As temperatures rise, you can begin planting more herbs. In warmer districts, some frost-resistant herbs can be planted outdoors during September. Suitable choices include:
Chives, chervil, parsley, rocket and dill.
Keep an eye on local weather conditions, particularly if you are gardening in a frost-prone area. Young herb plants can be surprisingly vulnerable to a late frost. September is also a good time to prepare your herb garden for the busy growing season ahead by removing weeds, improving the soil and making sure plants have adequate space to grow.
Fruit Trees and Fruit Gardening in September
September is an important month for fruit gardeners. As spring growth begins, fruit trees are becoming more active and there are several jobs that can be done now to encourage healthy growth and a good crop later in the season.
Pip and Stone Fruit Trees
Pruning of deciduous fruit trees should generally have been completed by now. September is also a good time to protect pip and stone fruit trees from fungal diseases. A suitable copper-based fungicide, such as copper oxychloride or Bordeaux mixture, can be used where appropriate. Always follow the product label instructions, including the recommended application rate and timing. Different fruit trees and cultivars can have different requirements.
Grafting Fruit Trees
If you want to graft your own pip or stone fruit trees, September is a good time to prepare for the job. Scion wood is generally taken from healthy young twigs around pencil thickness. If you collected scion wood earlier, it can be wrapped in plastic and stored in the refrigerator until it is needed. Grafting is generally carried out in late September or early October, depending on the weather, the tree and the type of graft being used. The important thing is to keep the scion wood healthy and dormant until it is time to graft it onto the rootstock or an established tree.
Citrus Trees
Many citrus varieties are reaching maturity around September and may be ready for harvesting. As a general guide, fruit can be harvested when most or all of the green colour has disappeared from the skin, although the exact timing varies between varieties and growing conditions. Tangelos can benefit from being left on the tree a little longer, as additional time can allow their sweetness to develop. Try not to leave mature citrus fruit hanging on the tree indefinitely. Overripe fruit can become dry and less pleasant to eat, and leaving large amounts of fruit on the tree for too long may also affect flowering and the following season’s crop. Rather than relying entirely on skin colour, consider the variety, fruit size, flavour and typical ripening time when deciding when to harvest.
Feijoa Trees
September can be a useful time to prune feijoa trees, particularly if the tree has become overcrowded. Remove selected branches to open up the canopy and allow more light and air to reach the interior of the tree. Avoid removing too much healthy growth at once. A light, selective prune can help maintain the shape of the tree without unnecessarily reducing future fruiting wood.
Berry Fruit Gardening Tips NZ
Spring is an important time for berry fruits. Fertilise established berry plants as they begin their spring growth, using a fertiliser suitable for the particular type of berry. This is also the time to start thinking about protecting your developing fruit from birds. Once the berries begin to ripen, birds can quickly discover them and may take a significant proportion of the crop. A properly supported bird netting system can protect your berries while still allowing you easy access for harvesting.
Raspberries, Blackberries, Boysenberries and Loganberries
Pruning of raspberries, blackberries, boysenberries and loganberries should generally have been completed by September. If pruning has been missed, check the requirements of your particular variety before cutting. Different types can produce fruit on different-aged canes, so pruning them incorrectly can remove next season’s fruiting wood. Tie suitable canes to their supports and remove weak, damaged or unwanted growth where appropriate.
Gooseberries and Blackcurrants
Pruning of gooseberries and blackcurrants should also generally have been completed by now. If your plants are becoming overcrowded, maintaining an open framework of branches helps improve air circulation and allows sunlight to reach more of the plant. After pruning, clear away old leaves and other debris around the base of the plants to help keep the area clean and reduce potential disease problems.
Strawberries
September is a good time to plant strawberries. Choose a sunny position with fertile, well-drained soil. Strawberries don’t like sitting in constantly wet soil, so improve drainage if necessary before planting. Keep the plants well watered while they establish, particularly if spring conditions are dry. As the fruit develops, remember that strawberries may need protection from both birds and garden pests such as slugs and snails. Bird netting is one of the most effective ways to protect a strawberry crop. A simple frame over the plants allows you to hold the netting above the foliage while still giving you easy access for picking. Avoid laying netting directly over the plants where birds or other animals can become trapped.
Greenhouse and Glasshouse Gardening Tips
Spring is the time to get your greenhouse or glasshouse ready for the busy growing season ahead. Start by removing dead leaves, old plant material and weeds. Give the growing area a good clean and remove any material that could harbour pests or diseases. Add fresh compost or other suitable organic matter to the growing beds and dig it in if that suits your preferred gardening method.
Growing Tomatoes in the Greenhouse
September is a good time to plant tomatoes in a greenhouse or glasshouse if you want an early crop. Tomatoes are frost sensitive, so a protected growing environment can give them a useful head start compared with plants grown outdoors. Make sure there is adequate ventilation as temperatures rise. A greenhouse can become surprisingly hot during sunny spring weather, even when the outside temperature feels relatively cool.
Starting Seeds Under Cover
A greenhouse or glasshouse is also an excellent place to start seeds that will eventually be planted outdoors. Sowing seeds in containers under cover gives young plants protection from cold weather and can give them a head start on the growing season. Once the seedlings are large and strong enough, they can gradually be hardened off before being planted into their permanent outdoor position.
Pot and Container Gardening Tips NZ
September is a good time to give your container plants some attention before their spring growth really gets underway. Start by removing dead leaves, dead stems and other unwanted material. Dust can also accumulate on the leaves of indoor and container-grown plants, so gently wiping larger leaves with a damp cloth can improve their appearance. Check plants carefully for insects and other pests. Spring growth can attract a range of pests, and dealing with problems early is much easier than allowing them to become established.
Repotting Container Plants
Check the roots of plants that have been growing in the same container for some time. If a plant has become root bound, it may benefit from being moved into a slightly larger container with fresh, good-quality potting mix. Don’t automatically move every plant into a very large pot. A container that is much larger than the existing root system can hold excess moisture and potentially contribute to root problems. After repotting, water the plant thoroughly and allow excess water to drain away.
Feeding Container Plants
Spring is also a good time to begin feeding container-grown plants as their growth increases. A suitable slow-release fertiliser can provide nutrients over an extended period. Follow the manufacturer’s instructions and avoid applying more fertiliser than recommended. Plants in containers have a limited amount of soil available to them, so nutrients can become depleted more quickly than they do in garden beds. A little regular attention now can help keep container plants healthy and attractive throughout the spring and summer growing season.
Ornamental Gardening Tips
Spring is when the ornamental garden really starts to come alive. September is a busy month for planting, sowing, dividing perennials and keeping weeds and garden pests under control.
Rose Gardening Tips NZ
September is a good time to give your roses some attention as they begin their spring growth. A copper-based fungicide such as copper oxychloride can be used where appropriate to help protect roses against fungal diseases. Spraying oil may also be used as part of a pest-control programme. Always follow the instructions on the product label and check that the products you intend to use are suitable for roses. Apply a layer of compost or well-rotted organic matter around the root zone of your roses to improve the soil and provide nutrients. Keep mulch and compost away from the crown and main stems of the rose. Leaving a small gap around the base of the plant helps reduce the risk of problems caused by excessive moisture around the crown.
Flowers and Flower Gardening Tips NZ
September is an exciting month for flower gardeners, with a huge range of annuals and perennials ready to be sown or planted. Start by clearing weeds and removing dead plant material from flower beds. Keep an eye out for snails and slugs, which can cause considerable damage to young seedlings and tender spring growth. If you are using snail and slug control products, choose products carefully and use them according to the label directions, particularly if you have pets or want to encourage wildlife such as birds and hedgehogs in your garden.
Flowers to Sow in September
Depending on your local climate and growing conditions, flowers that can be sown during September include:
Alyssum, amaranthus, aster, balsam, bedding begonia, Californian poppy, carnation, celosia, chrysanthemum, cleome, cosmos, dahlia from seed, delphinium, dianthus, everlasting daisy, gaillardia, gazania, geranium, gerbera, gloxinia, gypsophila, honesty, impatiens, marigold, mignonette, nasturtium, nemesia, petunia, phlox, rudbeckia, salvia, snapdragon, spider flower, statice, strawflower, sunflower, Swan River daisy, verbena, viscaria and zinnia.
Remember that sowing times can vary considerably throughout New Zealand. In colder areas, some seeds may need to be started under cover until temperatures increase.
Flower Seedlings to Plant
September is also a good time to plant established flower seedlings. Suitable choices can include alyssum, aquilegia, Canterbury bells, carnations, cornflower, cosmos, cineraria, delphinium, pansies, polyanthus, poppies, gypsophila, forget-me-nots, hollyhocks, stock and violas. Water newly planted seedlings well and protect them from slugs and snails while they establish.
Divide and Replant Perennials
Spring is a good time to lift, divide and replant many established perennial plants. If a perennial has become overcrowded, flowering has declined or the centre of the plant has become bare, lifting and dividing it can rejuvenate the plant and give you several new plants for other parts of the garden. Replant divisions into well-prepared soil and water them thoroughly while they establish.
Dahlias and Begonias
September is a good time to plant dahlia and begonia tubers as the soil begins to warm. Choose a sunny, well-drained position and prepare the soil with compost or other suitable organic matter before planting. In colder or frost-prone areas, wait until the risk of severe frost has passed or start the tubers in containers under cover before planting them outdoors.
Trees and Shrub Gardening Tips NZ
September is an excellent time to plant new trees and shrubs. Planting early in the growing season gives trees and shrubs plenty of time to establish their root systems before the hotter and drier conditions of summer arrive. Prepare the planting hole properly and give newly planted trees and shrubs plenty of water while they establish. Before planting, consider the eventual size of the plant. A tree that looks small when purchased can become very large over time, so make sure there is sufficient room for the mature plant. September is also a good time to fertilise established trees and shrubs as spring growth gets underway. Use a fertiliser appropriate for the particular plant and follow the application instructions. Avoid excessive fertilising, as more is not necessarily better and can damage plants.
Lawn Gardening Tips NZ
Spring is when your lawn begins growing more vigorously, so regular mowing becomes increasingly important. As a general guide, mowing every couple of weeks may be sufficient early in spring, although faster-growing lawns may require more frequent mowing as the weather warms. Avoid cutting the grass too short. Keeping the lawn around 20 to 25 mm high can help maintain a dense, healthy lawn while reducing stress on the grass. Try not to remove too much of the grass blade in a single mowing. If the lawn has become very long over winter, gradually bring it back to the desired height rather than cutting it extremely short in one go.
Controlling Lawn Weeds
If your lawn contains a lot of weeds, September can be a good time to tackle them. Removing weeds before they flower and produce seed can help reduce problems later in the season. Where bare patches have developed over winter, prepare the soil and sow suitable lawn seed to fill them. Keep newly seeded areas moist until the grass has germinated and established.
Compost Gardening Tips NZ
Spring is an excellent time to make use of the compost that you have produced over the previous months. Compost that has broken down to the point where the original ingredients are largely unrecognisable can be spread around established plants as a mulch or incorporated into garden beds when soil conditions are suitable. Adding compost to the garden improves the soil and returns organic matter and nutrients to the growing environment.
Starting a New Compost Heap
September also provides plenty of material for starting or adding to your compost heap. Grass clippings, fallen leaves, vegetable scraps and other suitable organic garden and kitchen waste can all contribute to a productive compost heap. A mixture of different materials generally produces better compost than a heap consisting almost entirely of one type of material. Animal manure can be added where suitable, and a small amount of lime can also be used if appropriate. Avoid adding unsuitable materials such as meat, dairy products, diseased plants or anything else that your particular composting system does not support.
Turn Existing Compost
If an existing compost heap has not decomposed sufficiently, turn and mix the material. Turning introduces air into the heap and mixes the different materials together, helping decomposition continue. Keep the compost moist but not saturated. A well-managed compost heap should gradually break down into a dark, crumbly material with a pleasant earthy smell.
September Gardening in New Zealand
September is one of the busiest and most rewarding months in the New Zealand gardening calendar. The combination of warmer temperatures, longer daylight hours and increasing plant growth means there is plenty to do. Prepare your vegetable beds, start sowing and planting, look after fruit trees and berries, control slugs and snails, tidy your flower beds and get your lawn and compost heap ready for the months ahead. Remember that New Zealand’s climate varies significantly from Northland to Southland and from coastal areas to inland and higher-altitude gardens. Use these September gardening tips as a general guide and adjust planting and other tasks according to your local conditions. The most important thing is to make the most of the beginning of the growing season while keeping an eye on the weather. Late frosts can still occur in many parts of New Zealand, so don’t rush frost-sensitive plants outdoors until conditions are suitable.