Well, it’s official. I’m am definitely over this excessive rain, and so are my chickens, dogs, cats, guinea pigs and everything in my garden, including my plants and trees.
While a couple of weeks has done a lot of good in the garden, greening up everything, helping food production and growth, and bringing frogs and other life, the pendulum has swung and enough is enough. I am beginning to see signs of water logging in some beds, the chickens are unhappy and I’m seriously behind on all major projects around the house. Including just the ability to catch up and clean up since before Christmas.
The bad news
So what happens in our gardens when they start to get water logged? What does water logged mean? How much rain is too much rain, and what damage can it cause in the short term? When the ground simply can’t absorb or drain anymore water, water starts to sit in the soil, and for too long, which causes loss of macro and microbial life, such as worms, beetles, spiders and other arthropods, plus all the good bacteria, protozoa, nematodes and many more, through either mass exodus or death.
At the same time, organic material in and on the soil, such as compost, mulch, manure, etc reaches maximum water absorption and starts to rot. This can cause problems when the rain stops and the sun comes out, in the form of smell from decaying matter, and the usual suspects that this brings, such as flies, maggots and others. This drenched, rotting matter can also stay wet in the soil for longer than needed when rain stops, continuing to rot plant and tree roots if too close to them.
At the point when plants and trees simply cannot ‘drink’ any more water, or store any more water in their roots, root rot can set in if roots are not in well draining soil, causing damage or death. This will occur faster in species that don’t like ‘wet feet’, while others will survive and withstand wet feet for longer periods.
When a garden bed or soil has reached maximum absorption water will appear to sit on the surface in puddles, or garden beds with borders can even fill up. If this water sits in the bed or soil, without any drainage, for more than a day (after already prolonged rain), damage can set in. Roots literally drown. At this point, maximum saturation has occurred and detrimental processes kick in. Some plants or trees may show signs of water logging quickly, such as yellowing leaves, rotting of leaf veins, leaves falling off, wilting and softening, darkening of root colour, with usually a decayed smell, as the skin or bark of roots is rotting. Other signs include young shoots and tips dying off, stunted growth, low or no seed or fruit production, and often swelling. Any or all of these equal stress for the plant or tree. And of course any seeds or seedlings planted are very unlikely to germinate or mature due to swelling and rotting.
A little science
Water logging causes problems for plant and tree roots in a few ways:
- Root function is reduced because of limited oxygen and CO2 diffusion
- This attracts organisms that feed on decomposing roots
- This also the prevents the stems, leaves, etc of the plant from obtaining nutrients and water (even though there is too water in the ground and roots)
- Water logging in summer and warmer climates is much more damaging because root oxygen-CO2 exchange is a lot more active and demanding. Plants and trees can often survive water logging much better in winter or cold climate soils
- Aquatic and marginal aquatic plants, plus some ‘wet feet’ plants and trees, can survive very well in water logged soils
- Some soils are more water logging than others, because of their denser texture and poor drainage qualities, and will remain very wet for longer periods after rain has stopped
Some short term solutions and remedies
- After heavy, prolonged rains or flooding, wash or sweep up organic and other matter which may have collected along pathways, drains and surfaces, to prevent this material from polluting and decaying on or near garden beds. In floods especially, this matter can be polluted or contain toxins. Do not handle without gloves.
- Avoid walking or moving on soil to reduce compaction and muddying soil. Only work your soil again when it has suitably dried out and is ready to be worked
- On inspection, gently remove as much water logging affected parts of plants as possible – leaves, shoots and tips, branches, etc, plus pull out and dispose of any dead or affected plants and trees
- After flooding, do not eat edibles for a while, as they may contain pollutants. Discard any suspect plants or fruit, especially edibles that are eaten raw
- Avoid growing edibles in soil or beds you suspect may contain toxins, especially edibles eaten raw and quick grow crops like salad greens
- Because of leaching in floods and water logging, apply a suitable fertiliser and mulch to the soil once conditions are favourable again
- Quality foliar (leaf surface) fertilisers can also help to rebuild and nourish water logged plants and trees
- Once you think plant and tree roots are no longer water logged, water them well, as they can suffer from not enough water, even after a flood or heavy prolonged rains
Some longer term solutions and remedies
- Seek to improve your soil structure and drainage properties through healthy cultivation and soil fertility, such as increasing the humus content
- Try aerating your soil and beds with a deep soil aerator
- Create mounded or raised garden beds for planting where possible
- Increase drains and drainage around and away from garden beds to divert rain and flooding where possible
- Create flow stoppers to slow down water flow into certain areas when flooding or heavy rains
- In lower areas that are more susceptible to water logging or flooding, choose water loving plants and trees, or those more tolerant of wet feet and wet soils
With a little common sense and planning, gardens be improved to prevent, reduce or minimise water logging and light flooding. Low areas or beds can be raised, or managed differently, such as growing different plant species. Soils can be improved to drain better. General drainage and water flow can be improved around gardens and properties. There is usually always a solution to water logging and flooding challenges. It just requires a little work and design. Best of luck!