What to grow in September 2021

September weather encourages many gardeners to start sowing. However, keep a watch on weather forecasts as a brief warm period in Spring can suddenly turn into a cold snap, and nights can be quite chilly. Keep an eye on seedlings and provide delicate species with a warm, sheltered spot before planting out when nights are warmer, or use a cloche to protect those you may have planted out too early.
The following gardening advice is an abbreviated list for vegetables, fruit trees and some culinary herbs that can be sown or planted during September in Australia and New Zealand. A comprehensive monthly guide that includes planting times for the entire garden, as well as when to fertilise, prune, weed, take cuttings or divide plants, can be found in my book Easy Organic Gardening and Moon Planting (Scribe Publications, 2006, 2009, 2012 and 2017, with moon planting 2017–2022), and e-book (Booktopia 2012, 2017).
* For gardeners who do not use moon planting: sow or plant out any of the following list at any time this month, although you may find germination rates are lower when the Moon is in Last Quarter phase..

WARM CLIMATE – South of Rockhampton
Before the Full Moon, suitable grain crops, lettuce, mizuna, rocket, silver beet, NZ spinach, tatsoi, nasturtium and sunflower can be sown directly into beds, as well as a green manure crop of pigeon pea, millet, Japanese millet or mung bean, if water is available.
Cabbage, suitable open-headed Chinese cabbage, parsley, spring onions and sweet basil can be sown or planted out.
During First Quarter phase, bush and climbing beans, pumpkin and sweet corn can be sown directly into beds, and capsicum, cucumber, eggplant, rockmelon, rosella, summer squash, tomato, watermelon and zucchini can be sown or planted out.
During Full Moon phase, Jerusalem artichoke, beetroot, carrot, potato (Brisbane and areas south), radish and sweet potato can be sown directly into beds, and asparagus seed, banana passionfruit, passionfruit, pawpaw, and chives can be sown or planted out. Avocado, banana, citrus, tropical and cherry guava, macadamia, passionfruit, marjoram, mint, oregano, sage, and thyme can be planted.

WARM CLIMATE – Rockhampton and northwards
Before the Full Moon, suitable cabbage, suitable lettuce, silver beet and NZ spinach can be sown directly into beds, as well as a green manure crop of pigeon pea, lablab or millet. Parsley, spring onions and sweet basil can be sown or planted out.
During First Quarter phase, bush and climbing beans sweet corn can be sown directly into beds, and capsicum, cucumber, eggplant, rosella and watermelon can be sown or planted out.
During Full Moon phase, beetroot, carrot, radish and sweet potato can be sown directly into beds, and banana passionfruit, passionfruit and pawpaw can be sown or planted out. Avocado, banana, citrus, tropical guava, macadamia, passionfruit, lemongrass and mint can be planted. Also plant marjoram, oregano, sage and thyme where they won’t become waterlogged.

TEMPERATE CLIMATE
Before the Full Moon, suitable Chinese cabbage, grain crops, lettuce, mizuna, rocket, and tatsoi can be sown directly into beds, as well as a green manure crop of chickpea, clover, barley or millet. Celery, leek, lettuce, silver beet and spring onions can be sown or planted out. Cabbage, parsley and sweet basil can be sown in a cold frame, and NZ spinach, coriander and dill sown direct after frost.
During First Quarter phase, bush and climbing beans, and sweet corn can be sown directly into beds, in frost-free areas. Capsicum, cucumber, eggplant, pumpkin, rockmelon, tomato, summer squash, watermelon and zucchini can be sown in a cold frame.
During Full Moon phase, Jerusalem artichoke, carrot, potato and radish can be sown directly into beds, and asparagus seed, beetroot, sweet potato and chives can be sown in a cold frame. In frost-free areas, banana passionfruit, passionfruit and tropical guava can be planted. After frost, avocado, blueberry, citrus, cherry guava, macadamia, olive, marjoram, oregano, sage, rosemary, French tarragon, thyme and evergreen trees, shrubs and vines can also be planted.

COOL CLIMATE
Cool climate gardeners may still need a cloche this month to protect young seedlings.
Before the Full Moon, grain crops, lettuce, radicchio and rocket can be sown directly into beds, as well as a green manure crop of clover, broad beans, field pea, barley, oats, triticale or wheat. Cabbage, celery, bulb fennel, leek, silver beet and spring onions can be sown in a cold frame. In very cold areas, broad beans, peas and spinach can also be sown.
During First Quarter phase, capsicum, cucumber, leek, suitable pumpkin, suitable rockmelon, summer squash, tomato, watermelon and zucchini can be sown in a cold frame, or after frost.
During Full Moon phase, Jerusalem artichoke, carrot, potato and radish can be sown directly into beds. Asparagus seed and globe artichoke can be sown in a cold frame.
After frost, potted grapes and evergreen trees, shrubs and vines can be planted, and turf can be laid.

What to grow in August 2021

If you have a cold frame or a warm, protected verandah, you can get an early start on growing tomatoes in August. Sow seeds in small pots and, when they are about 15 cm high, lie the pots on their side. The stem will turn 90° to grow upright and auxiliary roots will start to grow along the horizontal part of the stem. Don’t forget to keep the pots watered. When planted out, these extra roots allow the plants to absorb more water and nutrients, and help keep the plants less stressed in the heat waves that are becoming more common.
August is the last month you can effectively get rid of Bindii (or Jo-jo as it is called in some places) as it will have produced flower heads by mid spring. The flower heads contain vicious spines. You can find methods of eradication of this pest here: Bindii or Jo-jo
The following gardening advice is an abbreviated list for vegetables, fruit trees and some culinary herbs that can be sown or planted during August in Australia and New Zealand. A comprehensive monthly guide that includes planting times for the entire garden, as well as when to fertilise, prune, weed, take cuttings or divide plants, can be found in the diary section of my book Easy Organic Gardening and Moon Planting; (Scribe Publications, 2006, 2009, 2012, 2017 with moon planting 2017–2022), and e-book (Booktopia 2012, 2017).

* For gardeners who do not use moon planting: sow or plant out any of the following list at any time this month, although you may find germination rates are lower when the Moon is in Last Quarter phase.

WARM CLIMATE South of Rockhampton
Before the Full Moon, cabbage, open-headed Chinese cabbage, grain crops, lettuce, mizuna, silver beet, spring onions, tatsoi and dill can be sown or planted out, and rocket and a green manure crop of wheat can be sown directly into beds. Sow chickpea, nasturtium, and sunflower when soil feels warm to touch.
During First Quarter phase, bush and climbing beans, and rosella can be sown. Capsicum, cucumber, eggplant, rockmelon, summer squash, tomato, watermelon and zucchini can be sown in a cold frame or warm, protected area.
During Full Moon phase, carrot, Jerusalem artichoke, potato (Brisbane and areas south), and radish can be sown directly into beds. Asparagus seed, beetroot, rosemary, thyme and watercress can be sown or planted out. Avocado, citrus, macadamia and potted grapes can be planted.

WARM CLIMATE Rockhampton and northwards
Gardeners in very warm areas have time to sow late crops of many varieties.
Before the Full Moon, cabbage, lettuce, parsley, and spring onions can be sown or planted out. Grain crops, NZ spinach, silver beet and sunflower can be sown directly into beds, as well as a green manure crop of wheat or lablab.
During First Quarter phase, capsicum, cucumber, eggplant, parsley, rockmelon, rosella, summer squash, sweet corn, tomato, watermelon and zucchini can be sown or planted out. Bush and climbing beans and sweet corn can be sown directly into beds.
During Full Moon phase, carrot, radish and sweet potato can be sown direct. Avocado, banana, banana passionfruit, citrus and passionfruit can be planted.

TEMPERATE CLIMATE
Sowing and planting this month will depend on whether your area is prone to frosts. Gardeners in Temperate areas with access to a cold frame can get an early start this month with some warmth-loving varieties.
Before the Full Moon, grain crops and mizuna can be sown directly into beds, as well as a green manure crop of clover, field pea, barley, or wheat. Dwarf peas and chamomile can be sown directly into beds in colder areas. Celery, leek and lettuce can be sown in a cold frame.
In frost-free areas, Chinese cabbage, rocket, silver beet, spring onions, tatsoi and coriander can also be sown directly into beds.
During First Quarter phase, capsicum, cucumber, leek and tomato can be sown in a cold frame.
During Full Moon phase, Jerusalem artichoke and potato can be sown directly into beds; also carrot in frost-free areas. Asparagus seed and beetroot can be sown in a cold frame. In frost-free areas, rosemary, thyme, avocado, and potted grapes can be planted.

COOL CLIMATE
August is still too cold and frosty for most plantings.
Before the Full Moon, English spinach can be sown directly into beds, as well as a green manure crop of broad bean (Faba bean) or field pea. Celery, leek and lettuce can be sown in a cold frame.
During First Quarter phase, dwarf peas can be sown directly into beds. Tomatoes and chamomile can be sown in a cold frame. In very cold areas, broad beans can be sown. (See post on when to sow Broad beans and peas for your local climate.)
During Full Moon phase, Jerusalem artichoke and potato can be sown directly into beds, and late season onions can be sown or planted out. Asparagus seed can be sown in a cold frame. Herbaceous perennial crowns can be planted. In very cold areas, deciduous trees, shrubs and vines can be planted.

What to grow in July 2021

July begins in Last Quarter phase this year – not the best phase for sowing seeds but good for general garden maintenance. Plantings in July are very similar to those for June, but in areas experiencing very cold winters with late frosts peas can be planted later because pea plants are frost hardy but the flowers are not. Don’t forget to snap some outer leaves of cauliflower plants and bend them over the curd to prevent the curds discolouring in sunlight.
Potatoes can be sown in warm temperate and temperate areas. Grape pruning should be completed this month. July is a good time to prune deciduous trees, shrubs and vines in frost-free areas.
General winter warning: If plants in your garden are damaged by frost, please resist the temptation to prune back the damaged parts until all danger of frost has passed. The damaged parts help protect the plants from further damage.
The following gardening advice is an abbreviated list for vegetables, fruit trees and some culinary herbs that can be sown or planted during July in Australia and New Zealand. A comprehensive monthly guide that includes planting times for the entire garden, as well as when to fertilise, prune, weed, take cuttings or divide plants, can be found in the diary section of my book Easy Organic Gardening and Moon Planting (Scribe Publications, 2006, 2009, 2012, 2017 with moon planting 2017–2022), and e-book (Booktopia 2012, 2017).

* For gardeners who do not use moon planting: sow or plant out any of the following list at any time this month, although you may find germination rates are lower when the Moon is in Last Quarter phase.
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WARM CLIMATE – South of Rockhampton
Before the Full Moon, grains can be sown directly into beds, as well as a green manure crop of red clover. Cabbage and spring onions can be sown. Lettuce and silverbeet can be sown in a cold frame.
During First Quarter phase, tomatoes can be sown in a cold frame.
During Full Moon phase, Jerusalem artichokes, radish and turnip can be sown directly into beds, as well as potatoes in Brisbane and areas south. Beetroot can be sown in a cold frame. Asparagus and rhubarb crowns, fig, pistachio and other deciduous trees and vines can be planted.

WARM CLIMATE Rockhampton and northwards
Before the Full Moon, open Chinese cabbage, grains, lettuce, mizuna, rocket, silver beet, tatsoi, chamomile, coriander and sunflower can be sown directly into beds, as well as a green manure crop of lablab or corn.
During First Quarter phase, bush and climbing beans, popcorn and sweet corn can be sown directly into beds, and pumpkin, spring onion, summer squash, tomato, watermelon and zucchini can be sown or planted out. Capsicum and eggplant can be sown in a cold frame.
During Full Moon phase, beetroot, radish, turnip can be sown directly into beds, and avocado, banana, fig and pistachio can be planted.

TEMPERATE CLIMATE
Before the Full Moon, a green manure crop of broad bean (faba bean) or field pea can be sown. In a cold frame, sow celery and lettuce. In frost-free areas, suitable lettuce and spring onions can also be sown or planted out. English spinach can be sown directly into beds in colder areas.
During First Quarter phase, dwarf broad beans and peas can be sown directly into beds.
During Full Moon phase, Jerusalem artichokes, garlic, potatoes and radish can be sown directly into beds, and mid season onion seedlings, asparagus and rhubarb crowns, kiwifruit, pistachio and other deciduous trees and vines can be planted. In frost-free areas, fig can be planted.

COOL CLIMATE
Before the Full Moon, English spinach can be sown directly into beds, as well as a green manure crop of broad bean (faba bean) or field pea.
During First Quarter phase, dwarf broad beans and peas can be sown directly into garden beds (see link in the June planting post on when to sow Broad beans and peas for your local climate).
During Full Moon phase, late season onions can be sown, and asparagus and rhubarb crowns, deciduous fruit trees and vines can be planted where frosts are not severe. In cold areas that receive winter rain, it is better to delay sowing potatoes until August.

What to grow in June 2021

June begins in Last Quarter phase, a great week to get those clean up jobs out of the way. Remember that peas and broad beans should be sown at a time that will avoid local frosts damaging the flowers, rather than strictly following set sowing times for temperate and cool areas. See: Broad beans and peas
Cold weather is setting in, and cold-sensitive seedlings in frosty areas will benefit from a ‘cloche’ to protect their tender leaves.
Check the soil pH around the cabbage family of plants. The pH should be close to neutral (7). When soil is too acid or alkaline, this group of plants is more likely to attract cabbage white butterfly and other pests
The following gardening advice is an abbreviated list for vegetables, fruit trees and some culinary herbs that can be sown or planted during June in Australia and New Zealand. A comprehensive monthly guide that includes planting times for the entire garden, as well as when to fertilise, prune, weed, take cuttings or divide plants, can be found in the diary section of my book Easy Organic Gardening and Moon Planting (Scribe Publications, 2006, 2009, 2012, 2017 with moon planting 2017–2022), and e-book (Booktopia 2012, 2017).

* For gardeners who do not use moon planting: sow or plant out any of the following list for your climate zone at any time this month, although you may find germination rates are lower when the Moon is in Last Quarter phase.

WARM CLIMATE South of Rockhampton
Before the Full Moon, cabbage, and grains can be sown directly into beds, as well as a green manure crop of barley, chickpea, red clover, broad bean (faba bean), field pea, or triticale. Lettuce, radicchio, English spinach and spring onions can be sown or planted out.
During First Quarter phase, dwarf peas can be sown directly into beds.
During Full Moon phase, radish and turnip can be sown directly into beds, as well as potatoes north of Brisbane. Asparagus and rhubarb crowns, fig, kiwi fruit, pecan and pistachio can be planted.

WARM CLIMATE Rockhampton northwards
Before the Full Moon, cabbage, open Chinese cabbage, grains, lettuce, mizuna, rocket, silver beet, tatsoi, chamomile and coriander can be sown directly into beds, as well as a green manure crop of barley, corn, lablab, or triticale.
During First Quarter phase, bush and climbing beans, popcorn and sweet corn can be sown directly into beds, and pumpkin, spring onion, summer squash, tomato, watermelon and zucchini can be sown or planted out.
During Full Moon phase, beetroot, radish, turnip can be sown directly into beds, and fig and pistachio can be planted.

TEMPERATE CLIMATE
Before the Full Moon, English spinach can be sown directly into beds, as well as a green manure crop of broad bean (faba bean) or field pea. In frost-free areas, lettuce and spring onions can also be sown or planted out.
During First Quarter phase, broad beans and peas can be sown directly into beds.
During Full Moon phase, garlic and radish can be sown directly into beds, and mid season onion seedlings, asparagus and rhubarb crowns, kiwifruit and pistachio can be planted. In frost-free areas, fig can be planted.

COOL CLIMATE
Planting is extremely limited in cool climates during both June and July. Before the Full Moon, English spinach can be sown directly into beds, as well as a green manure crop of broad bean (faba bean) or field pea. Broad beans and peas grown as a vegetable can be sown during First Quarter phase.
During Full Moon phase, mid and late season onions can be sown, and asparagus and rhubarb crowns can be planted, also deciduous fruit trees and vines where frosts are not severe. In very cold areas, leave planting of deciduous trees and vines until late winter.

What to grow in May 2021

It’s time to plant garlic in non-tropical warm and temperate climates, and sow garden peas in frost-free areas directly into a garden bed with a trellis to support the plants. Contrary to some garden guru advice, legumes do need compost or complete organic fertiliser added to the bed before sowing here as Australian soils do not naturally contain the rhizobia that fixes nitrogen in these plants. If you live in a frost-prone climate, remember that peas take about 14 weeks from sowing to harvest, and time the sowing of peas so that they will not be flowering during frost periods. The plants are frost hardy but the flowers are not. Don’t cut back asparagus plant until the foliage yellows, which is a sign that plants have withdrawn nutrients into the crowns for growth next spring.
It is International Composting Awareness Week from May 2 – 8 this year. For those who haven’t yet discovered all the wonderful benefits of compost, you can find more information here: Compost materials
Compost bins and tips
The following gardening advice is an abbreviated list for vegetables, fruit trees and some culinary herbs that can be sown or planted during May in Australia and New Zealand. A comprehensive monthly guide that includes planting times for the entire garden, as well as when to fertilise, prune, weed, take cuttings or divide plants, can be found in the diary section of my book Easy Organic Gardening and Moon Planting (Scribe Publications, 2006, 2009, 2012, 2017 with moon planting 2017–2022), and e-book (Booktopia 2012, 2017).
* For gardeners who do not use moon planting: sow or plant out any of the following list at any time this month, although you may find germination is weaker when the Moon is in Last Quarter phase.

WARM CLIMATE South of Rockhampton
Before the Full Moon, bulb fennel, open-headed Chinese cabbage, grain crops, lettuce, mizuna, radicchio, rocket, silver beet (pre-soak seed), spinach, tatsoi, chamomile and coriander can be sown directly into beds, also a green manure crop of barley, cereal rye, chick pea, white clover, faba bean, field pea, cereal rye, Japanese millet, oats, triticale, or wheat. Leek and spring onions can be sown or planted out.
During First Quarter phase, broad beans, and peas can be sown directly into beds.
During Full Moon phase, radish, turnip and garlic can be sown directly into beds, also potato north of Brisbane. Early season onion and watercress can be sown or planted out. Olive trees can be planted.

WARM CLIMATE Rockhampton and northwards
Before the Full Moon, bulb fennel, open-headed Chinese cabbage, grain crops, lettuce, mizuna, radicchio, rocket, silver beet (pre-soak seed), spinach, tatsoi and coriander can be sown directly into beds, also a green manure crop of barley, cereal rye, lab-lab, oats, or triticale. Fast-maturing celery, headed Chinese cabbage, leek, silver beet, spring onions, parsley, and chamomile can be sown or planted out.
During First Quarter phase, bush and climbing beans and peas and sweet corn can be sown directly into beds, and pumpkin, rock melon, summer squash, tomato, watermelon and zucchini can be sown or planted out.
During Full Moon phase, beetroot (pre-soak seed), carrot, radish and swede can be sown directly into beds, and evergreen trees, shrubs, and vines can be planted.

TEMPERATE CLIMATE
Before the Full Moon, open headed Chinese cabbage, lettuce, mizuna, spinach and tatsoi can be sown directly into beds, also a green manure crop of faba (broad) bean, field pea, barley or oats. (Cereal rye can be sown in frost-free areas.) In frost-free areas, grain crops, lettuce, radicchio and spring onions can also be sown or planted out.
During First Quarter phase, fast-maturing broccoli, broad beans, peas and chamomile can be sown directly into beds in frost-free areas. In frost areas, delay sowing broad beans and peas until June. Although the plants are frost-hardy, the flowers are not.
During Full Moon phase, radish, turnip, and garlic can be sown direct, and early season onion can be sown or planted out. In frost-free areas, strawberries can be planted out.

COOL CLIMATE
Before the Full Moon, suitable lettuce and spinach can be sown directly into beds, also a green manure crop of faba (broad) bean or field pea, oats, or triticale. Spring onions can be planted out.
First Quarter phase: Avoid sowing broad beans and peas too early in frost areas. Although the plants are frost-hardy, the flowers are not. Early June may be a better time this year.
During Full Moon phase, radish can be sown directly into beds, and early and mid season onion can be sown or planted out. Garlic can be sown in warmer areas, and raspberry and currants can be planted from mid May.

Banksia rose

This lovely climbing rose is a popular addition to many gardens. The Banksia Rose, (Rosa banksiae) or Lady Banks Rose, originated in China, and is named after the wife of famous botanist Sir Joseph Banks.
An evergreen rose with few, if any, thorns, it is a dense climber to about 6 metres – perfect for covering a fence or pergola. Masses of creamy yellow or white flowers are produced on long canes from spring onwards. The flowers have a delicate fragrance, some say reminiscent of violets.
PLANTING
This vigorous rose needs a well-drained soil in full sun or part shade where it won’t crowd out other plants. First fill the planting hole with water. This is important for two reasons. How quickly the hole drains indicates whether drainage is good or you will need to plant the rose in a raised mound. If the surrounding soil is not damp when you transplant, the water you apply after planting will be drawn away from the root ball into the surrounding dry soil, and the plant will look stressed several days after planting. The addition of compost to the planting hole, and a 5 cm layer of organic mulch to the soil surface, is very beneficial. Keep the mulch one hand width from the stem.
It is a hardy plant but it should be watered weekly for the first couple of months after planting if weather is dry. Then, only water when the top centimetre of soil is dry.
PRUNING
Climbing roses are pruned after flowering. Banksia roses are usually pruned by late summer when the main flowering flush has finished. As these roses flower on last season’s wood, just remove any damaged canes, and shorten the rest of the canes by one third. Hard pruning results in no flowers next spring. Prune new roses during First Quarter phase when sap flow is higher and growth response will be faster.

Citrus gall wasp

Galls or stem swellings on citrus trees need to be removed by pruning by the end of August, as very tiny black wasps emerge from the galls in September and October ready to lay a new batch of eggs in citrus stems. Because these wasps are poor fliers, they tend to reproduce on the same tree unless blown by wind to a new host.
Unlike many other wasps that assist pollination or are pest predators, the citrus gall wasp is a true pest. Eggs are laid in young stems of citrus trees, particularly lemon and grapefruit varieties, and the native finger lime. The larvae remain within the stem, stimulating the growth of cells, and causing a gall or swelling to form on the infested stem by early summer. Trees that are repeatedly attacked will become weaker and produce less fruit.
Originally, only coastal gardens of New South Wales and Queensland were affected, however, this wasp is spreading to other areas of Australia.
Do not add galls to the compost heap. Burn them, or dispose of them in a sealed plastic bag. It is very likely that the gall in the photo missed last year’s pruning because it is unusual for galls to reach that size in one season. As you can see, the tree in the photo is also affected by scale, and it is more common for citrus gall wasp to attack stressed trees. After pruning, water the tree thoroughly, and feed it with a complete organic fertiliser and as much compost as you can spare. A drink of seaweed extract tea will help it to resist further pest and disease attack.

Blossom end rot

A common problem affecting otherwise healthy tomato and capsicum plants during heat waves is blossom end rot, where partly formed fruit develops a dark, sunken patch furthest from the stem.
This is caused by calcium deficiency, and is not a disease. Like us, plants need a good supply of calcium to form a strong structure. Hot and very windy days increase transpiration (water loss) from plants in the same way we perspire to keep cool, and calcium can only be absorbed by plants as water-soluble, electrically-charged ions. This problem can also affect zucchini, pumpkin and melon plants.

During heat waves, daily watering rarely solves the problem. A deep watering a couple of times a week is more beneficial. If soil around plants is mulched to keep roots cooler and reduce water loss, an efficient way to water quickly is to place juice or soft drink bottles, neck down, beside plants. See: Watering in drought conditions

Other causes of blossom end rot are:

• Erratic watering
• Soil is too acidic (soil pH less than 6)
• Poor fertilising routine
• Overuse of fertilisers high in nitrogen or potassium, including some seaweed fertilisers
• Rarely, in very alkaline soil where calcium becomes insoluble.

Winter tomatoes

  There is nothing like the taste of vine-ripened tomatoes, and this is how my neighbour, Cheryl, keeps her tomatoes cropping through winter on the Mid-North Coast of NSW. The tomato plants self-seeded in the rose garden in front of her north-facing verandah and, as they grew, she trailed the foliage across the verandah surface. The plants get plenty of sun during the day and the verandah roof keeps the plants warmer at night and protects them from frost. This clever idea has worked very well and Cheryl has so many tomatoes, she has been giving them away.

Tomatoes can also do well during the colder months in pots on a protected north-facing verandah, as the potting mix in black plastic pots stays warmer than soil in garden beds. Fruiting on tomatoes depends on warm air and tomatoes do not need bees for pollination. Don’t forget to water the plants regularly, and give them a light application of complete organic fertiliser as flowers start to form, to ensure a sweet-tasting crop.

Rust diseases

There are hundreds of types of fungi that cause ‘rust’ on plants but each type has a limited number of host plants so that your whole garden is not likely to be overrun by rust.
Rust can occur in various seasons but it does need moisture to grow. It typically causes yellow or brown markings on upper surface of leaves, and small yellow or brown powdery growths on the underside of leaves. The powdery substance consists of fungal spores that can be blown about by wind, infecting other plants that are susceptible to that type of rust fungus.
Below, on the left, are pictures of rust on the underside if a frangipani leaf and typical signs of rust on grasses. Some leaf markings can be confused with fungal diseases. On the right are pictures of hail damage on a cycad and spores on the underside of a fern frond – which is how ferns reproduce.







Treatment
Basically, rust diseases are a sign of malnutrition that produces an unsuitable pH on the leaf surface. Plants, like humans and animals, are more prone to diseases when they have a poor diet, and rust diseases can be avoided by keeping plants growing vigorously – but this is not always possible in extreme weather conditions. Sulphur or copper are the usual treatments for rust. Both of these are nutritional elements that can be supplied by various fertilisers, including seaweed extracts. Seaweed also contains plenty of potassium that strengthens cell walls, sulphur, and trace elements (including copper) that boost plants’ immune systems.
For mild cases of rust, remove damaged parts of the affected plant and burn these, or dispose of them in a sealed plastic bag. Don’t ever compost them, as the spores may not be killed. Then give the plant a foliar feed of seaweed extract tea and water some into the ground over the root area. Improve your fertilising program using a complete organic fertiliser.
For deciduous plants, rake up and dispose of dropped leaves to avoid reinfecting the plant. Apply the seaweed tea at bud swell.
For more severe cases, after removing damaged foliage, plants can be dusted with elemental sulphur (flowers of sulphur. However, as the spores are under leaves and the dust can be difficult to apply, affected plants can be sprayed with wettable sulphur in cool weather only, as sulphur will damage plants when temperatures are over 24 degrees Celcius. Be aware too, that sulphur will also kill pest predators. If these are present on affected plants, apply chamomile tea (one tea bag to 500 ml water) instead.