How often should I water new plants?

Water a new plant thoroughly the day it goes in, then let the soil, not the calendar, tell you when to water again. Check the soil about an inch down, and in the plant's own root ball, and water when it is dry. Without rain, that usually works out to about once a week in average soil, more often in sand, and two or three times a week for container shrubs in summer heat. Keep it up through the first growing season.

The first three weeks matter most

Virginia Tech's native plant guidance is clear on timing: "The most critical period for watering all plants is right after planting and for three weeks after planting."^[1] It adds: "For vines, shrubs, and trees, this period continues through the first growing year."^[1]

The reason is the root ball. A new plant draws almost all its water from the small ball of soil it came in until its roots grow into the bed,^[6] and the potting soil of most container-grown plants holds only a one- to two-day supply of water.^[2] The bed around it can feel moist while the root ball is dry.

A practical schedule

The simplest rule is to check the soil about an inch deep to see whether it is moist or dry, then water if needed.^[1] As a baseline for dry weather:

• Average and sandy soil: If there is no rainfall and the soil is very sandy, watering might be required every 2 to 3 days; otherwise, once a week.^[1]
• Container-grown shrubs in summer: watering two to three times a week in summer can be expected during periods of no rainfall.^[2]
• Balled-and-burlapped shrubs: Balled-and-burlapped (B&B) plants usually need only weekly watering, because the mineral soil around their roots holds more water.^[2]
• Young trees: water heavily once a week during periods of no rain, soaking the soil slowly with a hose until the water reaches the top of the berm.^[3]

Over a growing season, plants need an average of 1 inch of water per week^[4] from rain and watering combined. A rain gauge in the garden takes the guesswork out of that.

How to water

Deeply, not often. Virginia Tech's tree guidance notes that watering lightly encourages shallow roots, while watering deeply encourages deep root growth.^[5] A slow trickle from a hose into a ring of soil around the plant soaks in where a quick spray runs off.

Early in the day, at the base. The advice is to water early in the morning, so the plant can take up water before the heat of the day and less is lost to evaporation.^[1] And "Watering at the base of the plant instead of over the foliage helps prevent diseases."^[1]

With mulch. Mulch slows water loss from the soil.^[2] Keep it 2 to 3 inches deep and off the stems.

On a system, once a week. For a large bed, a soaker hose or drip line saves hauling hoses. Virginia Tech suggests an irrigation system set to run once a week, with a rain sensor that shuts it off when it rains.^[1]

Don't drown them

More water is not always better. Virginia Tech warns, "Overwatering wastes water, may weaken roots and lead to root decay, and encourages undesirable weed growth."^[4] It also notes that either excessively dry soil or waterlogged soil can cause the same plant reaction: wilt,^[6] which is why so many people water a drowning plant even more. Always feel the soil first. If plants droop despite watering, see why new plants wilt after planting.

How long to keep it up

Establishment time depends on the plant: "Seeds and annuals can establish in a few weeks, while perennials and vines can take a few months or a year. Shrubs and trees can take up to three years to get established."^[1] Planting season matters too. Slow-growing species, B&B plants, or shrubs planted in the fall may need supplemental irrigation in the year after planting,^[2] because their roots have spread less by the following summer. Our guide to when to plant perennials in Virginia explains how timing affects watering.

Once plants are established, cut back sharply. For established native plantings, Virginia Tech's advice is to check the soil and, if needed, provide 1 inch of water per week during long dry periods,^[1] and an irrigation system should run once or twice a week, or only as needed, not every day.^[1]

Stop and call a pro if

• Water stands in planting holes a day after rain or watering; the bed needs drainage work.
• Plants keep wilting even though the root ball is moist and drains well.
• You need an in-ground irrigation system installed or extended, which is its own trade.
• You will be away for much of the first summer and need someone to water.

Browse more lawn and landscaping answers, see garden and bed planting services, or look up lawn and landscaping businesses around Blacksburg. For help planting or caring for a new bed, describe the job once and local businesses quote it.