Whoever coined the phrase 'Cool as a cucumber', was not experiencing 106 and higher, heat indexes. There actually are cases where watering plants may have to be done two and three times a day.
Love it. Be glad you are alive and able to do it. Or you could do it the sissy way and buy those big, hard, bitter, tough skinned cukes that were shipped all way across the country and taste like 'Yuck'!
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Watering the garden is a simple, but critical, task. Give them too much and plants will drown, too little and they will dehydrate. Some ways of watering are smarter than others, and once you get the hang of it, you will naturally develop a sense of how much water your plants really need.
With these small cheap greenhouses that are plastic covered and are good for propagating seeds and cuttings, this a good way to water your seed trays and pots without the real risk of drenching and getting droop and rot.
Tomato plants like evenly moist soil. Many gardeners have good success watering them by using plastic bottles, such as milk or soda, planted near the base of the plant and filled from the top. Watering deeply is good for the plant's root system. This is a page about watering tomato plants.
Save water and ensure that your outdoor plants get watered even if you are away. These wick based systems will pull water from a reservoir when the soil gets dry, keeping your plants green and healthy.