AWhen we don our quintessential Australian winter uniform – down jacket, boots and umbrella – in an attempt to brave the plummeting (albeit still relatively balmy) temperatures, it can be easy to forget about our plant friends who are also experiencing the wrath of winter.
Seasonal factors, including less sunlight and increased rainfall, can create problems for gardens across Australia, but the severity of these impacts will depend on where you live in the country. .
“The further you live from the equator, the more you feel the effects of the Earth’s tilt relative to the sun,” says Terra-Nova Sadowski, horticulturist at the Royal Botanic Garden in Sydney. That means southern states — and their factories — often feel the brunt.
So what problems can this change of season create in our gardens and what can you do about it?
“Frost is a layer of ice that forms on the surface of plants, which causes the cells inside the leaf to freeze, expand and then rupture. As the leaf thaws, it turns to mush,” says Scott Yates, horticulturist at the Royal Botanic Garden in Sydney.
The effect of frost damage on our plants can vary greatly and is more likely to occur on clear, cloudless nights and lower on a slope when cold air descends.
“Damage appears differently on different plants, but may show up as brown or burnt leaves (especially on exposed tops of plants), blackened leaves, stem collapse, loss of foliage, blooms or fruit, even death,” says Yates.
Because it’s not freezing temperature that damages plants, but rather when it starts to thaw in the sun, John Arnott, director of horticulture at the Royal Botanic Gardens Cranbourne in Victoria, suggests getting up early in the morning. frosty morning – before sunlight reaches the plants – and water them with cold water. “This will remove the frost and prevent damage from slow thawing in the sun.”
Sadowski also recommends placing plants in raised beds to prevent frost from settling on foliage and erecting a screen or cover over susceptible plants at night. “But remember to remove in the morning once the risk of frost has passed.”
Increase in precipitation
“Higher than normal rainfall in winter…can lead to saturated, waterlogged soils and the inability of plant roots to breathe,” says Yates.
Some signs that heavy rainfall has caused waterlogged soils include water infiltration and surface water remaining long after the rain, moss and algae growth – as well as wilting, falling leaves, canopy thinning and plant death.
Arnott says one way to improve drainage and prevent waterlogged soils is to install gutters and drains or grow plants on mounds. That means “their root systems don’t sit in holes and the water drains away from the root plug,” he says.
Dominic Hooghuis, horticulturist and co-founder of The Plant Runner, says high rainfall can also create fungal diseases on some plants, which can easily spread.
“To help control the spread of fungal diseases, avoid overwatering and keep mulch and soil away from plant stems and trunks. Also consider delaying pruning and hedge trimming in rainy and humid conditions.
Strong, cold winds, particularly common in August, can cause significant physical damage to our plants.
They can also cause moisture loss, Yates says. Signs of damage to look out for include dry or brown burnt leaves as well as wilted, dry-looking plants (especially seedlings and new plantings).
Royal Botanic Gardens of Tasmania horticulturist Megan Marrison says: “If your plants are suffering, protect them from wind and frost with covers and screens. For example, lemons do not like strong cold winds where their leaves are damaged, and they can suffer from fruit drop. Drive in a few star stakes or long wooden stakes and attach a shade cloth to them with cable ties or screws.
“The signs of cold damage are similar to those caused by frost. The leaves can appear wilted and droopy, especially for plants from a warmer climate,” says Yates.
To remedy this, he suggests using a hothouse to grow more tender or warm-climate plants, or building or using existing structures to create a warm microclimate. Alternatively, you can plant or place cold-sensitive plants near a building or wall where they will be protected from cold winds, receive maximum sunlight, and benefit from radiant heat from the thermal mass of the structure.
“[The] the changing motion of the sun and shorter days can prevent plants from getting enough light to perform photosynthesis,” Yates says. This is something that can impact both our outdoor and indoor plants.
“In terms of light, try to have houseplants facing north so they can get as much light as possible,” suggests Arnott.
If possible, Yates also recommends repositioning outdoor plants, especially those that prefer warmer climates, in a north-facing direction as well. And indoors, grow lights can help with the growth and maintenance of a range of plants, including houseplants and vegetables.
Too much or not enough love
“Plants are your friends, so check them out to see if they’re doing well through the winter,” says Marrison. Finding that right balance of “love” is essential for our indoor and outdoor plants, she says.
“The two big things to watch out for are watering and fertilizing,” says Hooghuis. “The plants still need to be fertilized, but here too things have to change. Outdoors, consider using a low-nitrogen fertilizer or a slow-release organic product. Inside, reduce and halve the force and halve the frequency. You can resume as soon as spring arrives.
It is also time to reduce watering.
“In winter, plants often go dormant and they don’t take up as much water as they do in the warmer months,” he says.