[Don_1]

Whatever other points may be put forward I think the dominant factor is that rain generally puts down a lot more water than people usually bother to do with a watering can or hose.

This is most certainly a factor. No irrigation system can rival rainfall. As a general rule of thumb, 2.5cms of water is needed to penetrate 15cms of average weight soil. Very light sandy soil will be penetrated up to 30cms and heavy clay soils around 10cms by this amount of water.

On the question of oxygen, yes, plants do produce more oxygen than they need by day, but they use oxygen at night and do not produce any.

[Earthling]

Why do plants use Oxygen only at night?This is very interesting. Thanks for pointing this out.

[Don_1]

They use Oxygen day and night, but only produce oxygen by day.

[Earthling]

Thanks for the clarification. []

[Bored chemist]

Whatever other points may be put forward I think the dominant factor is that rain generally puts down a lot more water than people usually bother to do with a watering can or hose.

This is most certainly a factor. No irrigation system can rival rainfall. As a general rule of thumb, 2.5cms of water is needed to penetrate 15cms of average weight soil. Very light sandy soil will be penetrated up to 30cms and heavy clay soils around 10cms by this amount of water.

On the question of oxygen, yes, plants do produce more oxygen than they need by day, but they use oxygen at night and do not produce any.

Do you water the plants in the dark?

[Don_1]

Yes. The best time to water is after the sun has gone down, in the cool late evening. This allows more water to be absorbed by the soil, rather than evaporate before it has the chance to do so.

[Karen W.]

Yes watering at night is highly recommended  in my experience for the same reason Don states..

I was also thinking besides nutrients etc.. after a rain I always noticed when working outside and very strange warmth rising from the dirt on the ground just after rains.. I know the sun warms the earth and evaporation begins making the areas around the plant very humid.. with moisture and heat.. wouldn't that add to the spurting growth of the plants also?

It seems to aid in it to me as far as I can see anyway.. the warming of the moist earth seems to help the seeds also..

[Don_1]

Many of the plants in our gardens are cultivars or hybrids of wild plants from around the world, some from regions of high humidity. These plants will certainly benefit from the conditions you describe Karen and they are not alone. Even plants from the more temperate zones enjoy a little extra humidity sometimes.

Indoor plants should be misted regularly (except those like African violet, which do not like getting their leaves wet) to help maintain a degree of humidity and/or the pots stood on wet gravel. This does not apply to cacti which can withstand very dry air.

[Karen W.]

Cool Thanks Don !

I thought that the humidity and heat rising from the ground may aid in growth spurts!

[rosalind dna]

Whatever other points may be put forward I think the dominant factor is that rain generally puts down a lot more water than people usually bother to do with a watering can or hose.

This is most certainly a factor. No irrigation system can rival rainfall. As a general rule of thumb, 2.5cms of water is needed to penetrate 15cms of average weight soil. Very light sandy soil will be penetrated up to 30cms and heavy clay soils around 10cms by this amount of water.

On the question of oxygen, yes, plants do produce more oxygen than they need by day, but they use oxygen at night and do not produce any.

Do you water the plants in the dark?

Yes you should always water your plants once the sun has gone down because they will use less "energy" to use the water for their roots and growth.

If you water any plant on a very hot day then you'll scorch it and it will DIE.
I am speaking from experience here.

[Don_1]

Watering after sundown has many benefits and misting of some, especially climbers like the Clematis, can do them a power of good. But don't mist your Pelargoniums or climbing roses.

[dentstudent]

Another point about watering. If you are going to water shrubs during a drought, then make sure that you give them plenty! If you give a shrub/tree only a watering can load (10l or so), then what tends to happen is that this promotes fine root growth towards the surface of the soil, where you have improved the soil water capacity. This increases the plants reliance on upper soil moisture, rather than water from lower soil levels. Since the water in the upper levels is likely to evaporate more quickly, you are putting the plant into a potential water-stress situation. It can therefore be sometimes better to not water at all, since plants can adapt to low water conditions.