Wet Weather Gardening

After yet more rain on the east coast many plants in many gardens are suffering water-logging. Even in reasonably well drained soils the inundation has been too much for some plants. Physically, the force of rain, streams and puddles of water have caused their own damage and with the increased humidity comes increased pathogen risk, it really hasn’t put many gardeners in the best mood, myself included!

The biggest issue with waterlogging is often the deprivation of oxygen from the soil. If the soil can’t breathe then anaerobic bacteria take over and start producing the yucky smells we associate with long-wet locations. Most plant roots actually need oxygen to survive as well as air space to continue growing, so when soils sit wet for too long they literally start to suffocate.

From aboveground there’s not always much we can do to immediately alleviate water-logging, but noticing and designing your garden based on how water travels is a good first step. You can also add clay breaker or organic materials like mulches to help improve the structure of the soil and its ability to drain and hold air pockets.

Be mindful that after rain soils are vulnerable to compaction, and if compacted their ability to aerate again will be compromised. Try not walk excessively on or run heavy objects over still wet areas – unless of course you’ve turning the local hillside into a mudslide for the kids 😛 

Create some space around the base of your plants, especially young ones. After heavy rain debris and other materials sometimes accumulate around the stems of plants, which leads to increased humidity and a greater chance of pathogens taking hold. Plants can become completely covered in mulch after the rain so make sure you clear the base to allow for airflow.

Some native plants are more tolerant than others when it comes to having wet feet, sometimes this is called being hardy to ‘temporary inundation’, which just means their root system will tolerate sitting in water for a short period of time without harming the plant.

I have a heavy clay soil so am no stranger to trying to find native plants which will survive in poorly drained soil and have been trialling and testing some of the pictured natives species. As a general rule of thumb I have listed some species and genus below which don’t mind having wet feet, some of them even thrive.

Reeds, rushes and sedges are great in boggy damp areas, they will soak up excess moisture in difficult positions and can make great borders and features.

Banksia robur or the Swamp Banks ifs a wonderful large shrub or small tree which can handle very poorly drained soils and also periods of drought.

The WA peppermint will also cope with temporary inundation to its root system, this species can be found as a low shrub, large shrub and small to medium tree, so is very useful in clay soils, however it dislikes humidity so beware when growing it north of Sydney.

If you are looking for large Eucalyptus species which can handle a heavier soil and lots of rain, look no further than our beautiful Ironbarks!

Smaller hedging plants will be species which naturally grow in a wetter environment like the sub tropical rainforest, this encompasses plants like Lilly Pillys, Myrtles and Baeckea.

Other moisture loving small trees which don’t mind a bit of extra rain but cant sit for very long with wet feet are Grevillea baileyana, Buckinghamia celsissima, Tristaniopsis laurina and Xanthostemon chrysanthus.

Please see the list below and help me add to it!

• Leptospermum (not all species)
• Melaleuca (not all species)
• Callistemons (not all species)
• Casaurina species and cultivars
• Banksia robur
• Sedges – Carex apressa, Ficinia nodosa, Gahnia species
• Eucalyptus ampifolia, sideroxylon, paniculata
• Acmena and Syzygium species
• Baeckea virgata and linifolia
• Backhousia anisata, citriodora, myrtifolia
• Calothamnus quadrifidus
• Callicoma serratifolia
• Randia fitzlanni
• Lomatia myricoides
• Kunzea (not all species)
• Melastoma affine
• Native Grasses – Themeda triandra, Dianella caeurulea, Poa labillardieri, Pycnosorus globosus
• Viminaria juncea
• Tristaniopsis laurina
• Agonis flexuosa

By Kath Gadd and Hannah Preston