A once healthy clump of Geranium macrorrhizum struggling after too much rain

The flooding rains that have caused so much misery and property damage for many people in our state over the last few weeks have been utterly devastating. My heart goes out to all those who have been affected. In our area we have had about 700 ml rain during this time; I have nothing to moan about at all in terms of flood damage but it has been an instructive exercise to observe the effects - both positive and negative - of the huge volume of rain on plants in my garden and in the gardens of friends.

Buddleja crispa has died in my garden due to the recent rain

Buddleja crispa has died in my garden due to the recent rain

A number of plants have succumbed to the big wet. The main fatalities have been with plants of Mediterranean origin, which like well-drained soil and a dry atmosphere. Many such plants simply fail to thrive in our climate at the best of times but over the years, I have had success with a few - such perennial wallflower, Echium candicans, statice, Euphorbia species, edible sage, lavender and thyme, even though I had to replace them every few years. These plants have hated the constant wet weather and sodden soil and have expired, even in what I thought were quite well-drained beds. Silvery-leaved plants of many types have suffered (especially those with a furry texture) - and I have lost an old Buddleja crispa. I am not sure whether older specimens are more susceptible to being waterlogged, as a younger version elsewhere in my garden is OK.

Plectranthus ecklonii affected by too much rain

Plectranthus ecklonii affected by too much rain

Plants hailing from South Africa, also preferring in general drier rather than damper conditions, have taken a hit, especially those that have slightly furry foliage. Zonal Pelargonium, Leonotis and a some Plectranthus are some examples of those that have been lost in my garden and/or friends' gardens. Australian native plants that like particularly good drainage have also pegged out in some cases. The small-foliaged salvias such as Salvia microphylla and Salvia greggii plus their hybrid Salvia x jamensis normally do pretty well in Sydney, looking great at this time of year, but they have all become stringy and ugly, and some have actually gone to meet their Maker. These plants also originate in a fairly dry climate in Mexico which probably explains why this has happened.

The very humid atmosphere during the wet weather was not enjoyed by the plants mentioned, and this can cause fungal diseases of the leaves, especially in plants with a basal rosette of foliage close to the ground. Plant roots do need oxygen to respire, so constantly saturated soil will be a big problem, as will fungal root diseases that develop in damp conditions, causing root rot. Heavy clay soil like mine sees the most issues; gardens with sandier soil will have fared better. Some parts of my garden - at the bottom of a slope - are still very wet as there is poor drainage there. This is where the plants have suffered the most, no matter what their type. The best areas have been where the garden beds are raised, thus providing better overall drainage. Many potted plants have suffered from being constantly wet for so long; pot-bound plants seem to be particularly vulnerable.

It is so dispiriting to see first the wilting leaves and then the gradual desiccation of the plants as they succumb; or in other cases dissolving into a hideous, slimy mess. In some instances, I have been able to salvage a few pieces as cuttings before the whole plant conked out. I think it is better to dispatch the ex-plants into the green bin rather than the compost bin in case they are harbouring fungal diseases.

Not only have we had so much rain, but the concomitant factor is lack of sun, which spelled doom to my attempts to grow vegetables this summer. Even the tomato fruit that was produced, split open due to too much water. Most of my vegetable plants became slimy ruins and have now been ripped out. Snails and slugs have also enjoyed the damp conditions and seem to have multiplied exponentially, causing extra headaches!

Dahlia, canna and coleus thriving after the rain

Dahlia, canna and coleus thriving after the rain

On the whole, plants from humid, semitropical areas of the world have been the best survivors. Dahlia had tall stems damaged by the heavy rain but in general they have done pretty well this season and grown higher than normal. Another plant that has grown huge is the coleus - all of mine seem double their normal size. New Guinea Impatiens are also happy and I have seen the old-fashioned Impatiens thriving too, in my own garden and elsewhere. Canna and Colocasia (elephant's ears) are also flourishing.

Brunfelsia blooming now in the garden of Dianne and Charlie Mackowski in Sydney

Brunfelsia blooming now in the garden of Dianne and Charlie Mackowski in Sydney

Other semitropical plants have responded to the rain with multiple flushes of flowers - they do this anyway but their blooming has been quite magnificent this year with so much rain - for example, Brugmansia and Murraya, I also recently saw a gorgeous white Brunfelsia in a garden nearby to me that is smothered in blooms (possibly Brunfelsia americana or Brunfelsia portoricensis). The so-called rain lilies - Zephyranthes species - have also had quite a few flushes. Weeds are also very happy!

It seems likely that these sorts of weather events are going to become more frequent in the future. This is the second March in a row where we have had torrential rainfall. Now is a good time to assess drainage issues in our gardens and think about possible solutions. I am happy to replace some of the plants I have lost, understanding that they are vulnerable to this sort of weather, but I am also looking more appreciatively than ever at those that have flourished despite the very challenging conditions.