How to Water Plants

Understanding how to water plants in your garden is important.

Here we cover the signs of plant stress along with other simple rules of thumb that any gardener should know about watering plants.

Watering plants

What does it mean when watering trees and plants they need
one inch of water a month or one inch a week?

  • For mature trees:     
    1" monthly = 2 gallons per square foot

  • For mature shrubs and flowers:
    1" weekly = 4" monthly = 8 gallons per square foot

When first developing an understanding for this a rain gauge may help.  A homemade rain gauge can be as simple as an empty soup can.  If there is one inch of water inside can, this equals one inch of rainfall.  Remember, a rain gauge doesn't take into consideration irrigation, which is artificial means of watering.

Signs for Over-watering Plants:


  • Leaves become yellow then can begin to wilt, sometimes tips turn black.  After this, plant will stop producing leaves.

  • Root Rot - Soil becomes saturated where carbon dioxide builds up, not allowing the plant to receive necessary oxygen.  Stems turn dark green and become soft and stringy.

  • Mold growth on underside of leaves and moisture loving pathogens continue to rot and promote plant disease.

  • Plants become susceptible and begin having pests.

Signs for Under-watering Plants:

  • Plant is droopy indicating severe stress.  This is when roots don't take in enough moisture to replenish what is being evaporated. 

    Wilting is the life sustaining strategy where plant protects itself from taking in atmospheric carbon dioxide, which is necessary for photosynthesis.

  • Leaves yellow and begin to dry, especially around roots because plant is not getting needed nutrients.

  • Soil around plant is dry on surface although there still could be moisture underneath.

In time gardeners develop an eye for water stress, plant diseases
or a mineral deficiency.

When learning how to water plants
some quick tips below may be helpful.

1)  Take into consideration types of soil

  • Sandy soil requires more frequent watering because it drains quickly.  Important on how to water plants, sandy soils also tend to be nutrient deficient and drains three time faster than clay soil and two times faster than loam.

  • Adding a soil amendment to sandy soil when garden tilling improves quality and water retention.

  • Adding soil amendments to clay and heavy loam soils improves quality and opens them up for better water and air penetration.

  • Soggy soils that have poor drainage can exclude oxygen.  Oxygen is necessary for both roots and micro-organisms.

2)  Plant roots don't all have the same water holding capacity

  • A baby plant needs to be watered lightly and frequently because of their shallow roots.

  • Annual plants usually require a lot of watering.  Root systems may not be large enough and will dry as top-soil dries.

  • Necessary to water new plants more their first growing season.  This is for both annuals and perennials.

  • A perennial plant has a root system that continues to grow larger with each passing growing season.  This helps them to withstand droughts better.

  • Woody plants generally have extensive root systems that reach down into soil better over herbaceous plants.  Because of these longer roots woody plants are able to seek moisture out better while other plants suffer.

  • Deep roots are important in windy regions.  Wind increases soil evaporation.  Weeds will take over the needed water and nutrients from the soil.  It's a good idea to establish windbreaks, which helps for your butterfly garden to.

3)  Deep Watering

  • Water applied to the top 1 or 2 inches is a waste because it evaporates before plant can use it.  This creates weaker, smaller root systems to anchor plants down in soil.

  • Deep watering creates strong, hardier roots that grow larger and are able to withstand drought periods better. 

  • Best to water established plants, trees and lawns for thirty minutes, two times a week rather than ten minutes daily. 

    Roots penetrate more water when they grow deeper,  this way plant learns to survive on less water.

4)  Drainage after Rain

  • If areas in yard remain squishy while other areas have dried shows poor drainage.  Dig a hole about 24 inches deep, any width.  Fill with water and let drain completely.  Fill with water again and take note to how long it takes to drain.  Adequate drainage is a drop of 6 inches in 24 hours. 

    Install drainage tiles, build a raised bed or a small incline and place well drained top-soil and other matter.  Until this, try plants that like lots of water like those in bog gardens.

  • If soil drains faster than 6 inches in 24 hours water retention needs to be improved.  Place soil amendments or other matter in soil while garden tilling.  Choose plants that are more drought resistant until then.

5)  How to water plants during High Temperatures

  • High temperatures and low humidity cause plants to give off, or transpire, huge amounts of water in the air.  This creates a drain on soil reserves of water.

  • High temperatures and high humidity enables plants to retain moisture longer.

  • Vegetation begins to struggle when temperatures get 90 degrees and above.  If under-watering remains constant some trees and shrubs don't show signs of distress until the following year.

  • Heat + Mild water = More plant insects

6)  How to water plants and Save Money

  • Water in the morning or coolest part of the day.  This way plants dry off before evening and prevents moisture from evaporating too quickly.  This also helps prevent fungus.

  • Use mulch.  This will help to hold moisture in soil.


  How to water plants when Container Growing

Flowers that Attract Butterflies
  • Container flowers need more water as the soil dries out quickly.

  • Drainage holes are necessary at the bottom of plant container.

  • Container plants need to be watered at least once a day, especially during high temperatures.

  • Many who live in winter zones, container flowers aren't able to withstand being outside.  Potted plants need to be placed in warmer areas like porches where the sun can still reach them.

  • See guidelines above Over and Under-watering plants.

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