Some garden battles can’t be won but mitigated to some extent with better preparation/protection. Rain is beneficial to plants but to an extent. Heavy Rain/High amount of rainfall can cause havoc in your garden, all you can do is to prepare well and clean up afterwards.
Generally Indo-Pak region experiences CLOUD BURST phenomenon (high amount of rainfall is lesser duration) especially during Monsoon. Rain fall is highest in Monsoon and in the month of February-March for Northern areas.
Soil type of Garden and Rain Damage
Soil type in your garden plays important role in determining how much damage you are going to receive. If your soil is sandy/more portion sandy, water accumulation will be lesser, and high amount of accumulated water will seep into ground within few hours of rainfall, thereby solving one problem that is Root Rot due water standing for longer duration. Generally plants can survive standing water for couple of days.
Disadvantage of sandy soil is its lesser holding strength, therefore continuous rainfall will loosen it up/drain soil, resulting in weak base of plant making them flop. You can stake plants to protect them from falling over, but even that fails sometimes.
Sandy soil will cause uneven spaces, loss of soil/erosion, this erosion will result in roots being exposed which can be disastrous if not attend to as soon as possible after rain. Erosion will also result in stone being accumulated on the top of soil due their heavier size. These stones are already there but will come to the surface due soil erosion.
Another disadvantage of sandy soil due to its light nature is that it will get stick with the foliage, making plants dirty and unable to photosynthesis properly. Only way to overcome is washing them thoroughly. BUT as the soil is already wet and soggy you cannot do that. Wait for sun to dry some water and then you can lightly wash away plants through misting.
AVOID REWATERING FOR ATLEAST FEW DAYS. Future watering will be depending on the amount of rain received, type of soil and heat index of those days. For instance in winters if you have 50mm rain, and you have a quick draining sandy, you would not be requiring water at least for 3-4 days. Sun will only evaporate top moisture; therefore check condition of soil below few inches to have correct picture.
Clay soil/more portion clay has more holding power thereby lesser erosion, lesser chance of plants flopping over as well as dirty.
Clay soil can be nightmare due poor draining capability. The accumulated water will stay for days resulting in fungal diseases, Root Rot and plants not able to breathe through roots. Depending on water accumulated and type of soil, pumping or diverging the water out by channeling it somewhere are the only solution.
Sun Exposure following Rain
If possible ensure all rain affected pots and garden areas receive sunlight post rain. Shadier spots will need manual water removal which could be real pain.
Heavy rainfall for sure will cause many taller (above one foot) plants to fall over. Stake them. Make a soil base to strengthen these plants. Plants that fall over even then, must be immediately lifted and straightened after rain otherwise their shape will be deformed. Plants continue to grow, even more in rain. Stems grow against the gravity and into the sun; therefore they tend to get deformed if fallen over. Some will get their shape back with sun and some will remain deformed. YOU WILL HAVE TO LIVE WITH SOME CLUMPSY LOOKING STEMS.
Heavy rain will result in loss of fertilizer/nutrients seeping away with rainwater. Re-Fertilization will be required.
Hail or even continuous rain can cause broken leaves as well as bruises-holes on leaves. Nothing can be done about that, but plant will recover, however acquired progress will be lost, thus blooms delayed.
Post rain lot of cleaning will be required in the garden. However prioritize work. First tend to plants that are struggling. Cleaning can be done later.
Pre-rain ensure there is no debris in your garden or this will float with rainwater causing great structural damage.
Damage due High Wind
High winds can straight away break plants/trees into two. Stake plants, grow taller plants at a sheltered position such as alongside a wall/fence.
Falling branches will cause heavy damage if they fall over borders. Ensure pre rain to locate and prune weak tree branches. If you find fallen branch over plant, great care must be taken to remove it. Some plants are damaged by its falling but more by its improper removal.
Plants supported with trellis will require attention. You might need to adjust trellis disturbed by rain.
Accumulated water can result in fungal growth. After water removal be equipped with fungicides to counter any such outbreak.
Pot plants suffer lesser damage due rain, Moreover if you are expecting heavy rain, one must endeavor to provide shelter to all possible pots.
If your pot is placed at an uneven place/soil rain causes it to fall/drop, thereby damaging pot & plant. Ensure potted plants outside are placed on a good base.
High amount of water will cause soil and fertilizer to drain out of pots, require top dressing of both. Pot plants will be quick to let go of water provided medium is free draining.
Unusual pots such as square shape planters have poor drainage. ensure that you place them in shelter. If you can not take pots inside, place plastic cover over them, to avoid over watering. This plastic should be placed in a sloping position.
Protection on bigger scale
Nothing beats a green house, if you can erect one at your place, your plants will be protected not only from rain but from other weather atrocities as well.
Second most important aspect is that your garden should be leveled or high, not only within itself but also with the surrounding areas/roads. Otherwise all the rainwater will flow to your place. This aspect can be improved upon once making a new garden. If you already have a garden which is low lying as compared to the streets/surrounding area then you should raise the level where possible, else PRAY To GOD.
One neglected area is drains of roofs. Rain water accumulated on the roof tops fall down with great power breaking whatever is underneath it. Reposition (increase/decrease length) your drain pipes in such a way that no plant/part of garden is underneath. Grass won’t mind such drains this can cause erosion leading to bumpy turf.
Checklist Pre Rain
Secure Pots inside shelter if possible.
Stake all taller plants.
Remove debris/weak tree branches.
Checklist Post Rain priority wise.
Remove accumulated water.
Straighten all fallen over plants through staking/base strengthening.
Cleanup /Debris removal.
Deadhead faded flowers and foliage.
Replenish lost plants
No matter what you do some plants will die and will be required to be replaced with new ones.
Bad aspect. Load on pocket and man hours.
Good aspect. Chance for you to visit the nursery.