Well, does it? If you adhere to the common <a href="http://www.wisegeek.com/what-is-the-best-time-of-day-to-water-the-garden.htm" target="new" rel="noopener">advice from WiseGEEK</a> then we must answer in the affirmative.
The most common response to this question is: Plants should be watered in the morning to avoid fungal root diseases.

The logic plays out like this – if you water your plants in the morning then they will have time to dry out before nightfall. For at evening, once the sun has set, plants are unable to deal with water around their roots and become susceptible to all manner of fungal diseases. Really?

Let’s chew through this one a little more before we swallow it hollus-bollus.

Now, if this were a true statement then shouldn’t we be covering our plants when it rains during the night? And how many of us gardeners have had plants wilt and die from fungal root diseases after enduring months of rainy days and evenings? I’ll hazard a guess at none.

So, why should this argument have any credibility at all? Maybe it has to do with the temperature increase during watering periods. As with food, if it’s held at temperatures above 5°C and below 60°C you’re more likely to increase the risk of food spoilage. Perhaps the problems occur because we mainly water during our warmer months.

The problem with that argument is that these would increase bacterial disease – caused by bad hygiene practices – but have no affect on fungal diseases. Fungal diseases are usually a result of damp conditions.

If we’ve already dismissed that the time of day has little effect on damp conditions then there must be a culprit lurking in the corner. Let’s pull him out…[drum roll, please].

And the malefactor is not the time of watering but is instead – poor drainage.

Poor drainage can kill your plants quicker than a dose of glyphosate. Most plants don’t enjoy wet feet and would rather take their nutrients as quickly as possible and then be released from the burden of sitting in a ‘cold bath’.

This is why gardeners need to improve their soils. If they’re sandy and drain too fast then the plants will not be able to source enough nutrient and you will need to water more often. Those gardeners who suffer from clay soils will find that they don’t drain as readily. Find a balance between the two and suddenly you will have plants singing your praises and performing beautifully.

If you’re looking for some answers to improve your soil read on <a href="https://gardeningtipsnideas.com/2006/01/soil_problems_-_day_2_21_days_of_garden_fatigue.html">here</a>

Gardeners who accuse the time of watering for their plant failures have inappropriately blamed the wrong source. It has nothing to do with the time of day you water merely how well the soil drains around your plant roots.

If your plants have good drainage then enjoy the liberty of watering either first thing in the morning or last thing at night.