Improper watering is without a doubt the leading cause of plant death in
the landscape. One of the reasons that watering is so misunderstood is
that it can be difficult to tell someone exactly how much and how often
they should be watering. Each watering situation is different, and depends
on a number of conditions including the soil, weather, sun exposure,
mulch, whether or not the plant is actively growing, as well as the type of
plant in question. It’s important to know the conditions in which your plants
are going to best thrive. While some plants actually prefer more extreme
conditions such as wet or dry soils, most plants are somewhere in the middle
of the spectrum and like soil that is moist but well-drained. This means that if
you squeeze together some soil in your hand, it should stick together but fall apart easily.
Established trees and shrubs
Shrubs and trees that have been planted in the landscape for 2 years or more should be pretty well
established and should not require much supplemental watering. A good rule of thumb for the
average plant is that you want it to be getting approximately one inch of water per week during
periods without rain. If you have an irrigation system, you can determine the water output by putting
a shallow container such as a cat food or tuna can on the ground to catch the water. It’s
better if the plants receive this amount of water in 1 or 2 waterings rather than over several
waterings. It will encourage deep root growth and help prevent root rot.
Newly planted trees and shrubs
Shrubs and trees that are newly planted require more attention than established plantings. These
plants usually have a small rootball in comparison to the rest of the plant. Plants should always be
thoroughly watered in at the time of planting. Watering during the first month after planting is especially
critical. If we have little rainfall you may need to water every 2 to 3 days during warm
weather. The amount you apply should be enough to thoroughly moisten the rootball. Plants with
smaller rootballs, such as those in 1 or 3 gallon pots, often require more frequent watering than
plants with larger rootballs. Don’t be afraid to stick your finger down into the rootball to check for
moisture. After the first month, you should be able to decrease watering frequency. Plants planted
in the fall have longer to begin establishing a root system before the heat of summer, but they may
still require supplemental watering for up to 2 years after planting. Additionally, if we have long
periods without rain through winter, you need to check the soil moisture and water when needed.
Be wary if forecasters call for extended periods of freezing temperatures and dry conditions which
can be a death sentence for many plants.
Annuals and perennials
Annuals and perennials establish more quickly than shrubs or trees, but may have to be watered
more frequently once established. Watering during the first month after planting is similar to that for
trees and shrubs, every 2 to 3 days, although some plants may need daily watering initially. After
that first month, 2 to 3 times per week should be enough.
Tips for watering and for water conservation
• Water deeply to encourage deep root growth and promote better drought adaptability. Keep
water pressure low so water has time to seep in rather than run off.
• Provide a 2" to 3" layer of mulch to improve moisture retention and decrease watering (and cut
down on weeding). Be sure to keep mulch away from contact with the base of the plant.
• During warm weather, water early in the morning or in the evening to reduce evaporation.
• Choose drought-tolerant plants to reduce water needs.
• Consider using rain barrels to collect runoff from downspouts. Fill watering cans while waiting to
shower water to get hot.
• Be mindful of plants that may be getting watered when you irrigate your lawn and make sure
they are not staying too moist.
• Know the signs of improper watering. Wilting, brown leaf edges, and stunted growth are signs of
underwatering. Wilting which does not recover with watering can be a sign of overwatering.
• Group plantings by water needs placing drought-tolerant plant with other plants that like dry
conditions and plants that require more water with similar plants. That way you can water each
group accordingly. Extra tip: watering chores can be made easier by planting the drought-lovers
further away from the house while the plants that need more attention are closer to the house
(and the hose).
• Build a watering basin around plants so that water stays in the vicinity of the root zone instead of
running along the soil surface away from the plant’s roots.