How to Stop Container Plants From Drying Out So Fast

Find the Cause Before You Change Anything

Container plants dry out fast for four main reasons: the pot is too small for the plant, the pot walls are porous, the roots have filled the pot, or the mix has dried to the point where it repels water. Fix the one that applies and the watering interval stretches without further effort. A 5-gallon pot for a full-size tomato, a soak in a tub of water for a dried-out root ball, and a layer of mulch are the changes that most often solve it.

Some daily watering is normal. University of Illinois Extension says watering on a daily basis is necessary for containers in the growing season, and Iowa State notes that hanging baskets may need water once a day on hot, sunny days. The Royal Horticultural Society advises checking pots daily during warm or windy weather and twice daily in hot weather. The problem worth solving is the pot that wilts between those checks.

Watch what happens the next time you water. If water pours from the drainage holes within seconds and the pot still feels light, the mix is not absorbing it. If the plant is large and the pot small, the reservoir is simply too little. The sections below take each cause in turn.

Pot Size Comes First

A container holds all the water the plant can reach, so the volume of mix sets the upper limit on time between waterings. Penn State Extension singles out pots smaller than 10 inches in diameter as the ones that need water most often. University of Maryland Extension publishes a minimum container size for each vegetable:

Crop	Minimum container
Leaf lettuce	1/2 gallon
Bush beans	2 gallons
Cherry tomato	2 gallons
Standard tomato	5 gallons
Pepper	5 gallons
Eggplant	5 gallons
Cucumber	5 gallons
Summer squash	10 gallons

These are minimums. If your plant is in a pot well under the listed size, moving it up is the fix, and nothing in the later sections will substitute for it. Our pot size chart for vegetables lists more crops and converts pot diameter to gallons.

When you fill the new pot, stop about an inch below the rim. Maryland recommends that gap so water has room to sit on the surface while it soaks in. In a pot filled to the brim, water runs over the side before it can soak in.

Pot Material and Color

The walls of the pot matter nearly as much as its size. Maryland Extension states that containers made from porous materials, which it lists as clay, ceramic, concrete and wood, dry out more quickly than containers made from plastic, resin, fiberglass or metal. A thirsty annual in unglazed clay on a sunny deck is losing water through the pot as well as through its leaves.

Color adds to it. The same Maryland guide warns that dark container colors can raise the temperature of the potting mix and may injure tender roots. For plants that need steady moisture, a light-colored plastic or resin pot is the easier container to manage. Keep the clay pots for plants that prefer to dry between waterings. The trade-offs are laid out in our comparison of terracotta, plastic and fabric pots.

Roots That Have Filled the Pot

A plant that has outgrown its pot shows the symptoms of drought even when it is watered every day. University of Maryland Extension explains that a pot-bound plant holds a mass of impenetrable roots, so water passes through the pot too quickly, is not absorbed, and leaves the center of the root ball dry.

Slide the plant out and look. If roots circle the inside of the pot in a solid layer with little mix visible, that is the cause. Maryland’s remedy is to repot into a larger container and to loosen the tight root mass by hand, or cut it away, so the roots can spread into fresh mix. Simply dropping the intact root ball into a bigger pot leaves the dry core in place.

Mix That Repels Water

Peat-based and other soilless mixes are hydrophobic when dry. Maryland Extension puts it directly: soilless mixes tend to repel water. Iowa State adds that potting mix that becomes extremely dry will separate from the sides of the container, so the next watering runs down the gap and out the bottom.

There are two fixes, one for new pots and one for existing ones.

1. Before planting, work water into dry mix with your hands until it is thoroughly wetted. Do this in a tub or wheelbarrow, then fill the pot.
2. For a planted pot that has dried out, soak it from below. Illinois Extension advises immersing the container in a bucket or sink and leaving it to absorb water through the drainage holes. Iowa State gives times. A container that has dried out completely goes in a tub of water for 20 to 30 minutes. A hanging basket that is excessively dry gets 1 or 2 hours, and no more than 2 hours, because longer can cause root rot.

Never fill containers with soil from the garden to make them hold more. Maryland notes that soil is too dense to allow good air and water movement in a container. Old mix can be stretched, though. Maryland suggests blending last year’s media 50:50 with fresh mix or compost, and our guide to reusing old potting soil covers the details.

Water-holding gel crystals are sold as a cure. Illinois Extension describes them as a polymer mixed into the media before planting and adds that they lengthen the interval between waterings only slightly and do not eliminate the need for timely watering.

Mulch, Grouping and Shade

Once size, roots and mix are right, three smaller measures cut the remaining losses. Penn State notes that mulch slows the evaporation of water from the soil. The Royal Horticultural Society agrees that mulching pots reduces evaporation, with a caveat: most water is lost through the leaves, so careful watering is still needed. On seeded pots, wait a few weeks after germination before mulching, as Maryland advises, so seedlings are not smothered.

Grouping is the second measure. The Royal Horticultural Society recommends standing pots together to give each other shade and to raise the humidity of the air around them, which reduces how much water they need. A single dark pot alone on paving is the hardest container to keep moist.

The third is a saucer. The same society says saucers or trays placed under pots during dry spells in summer can help reduce water and fertilizer use. Remove them in winter.

Water Thoroughly, Then Check

How you water decides whether the whole root ball gets wet. Maryland’s standard is that each watering should thoroughly moisten the entire container, with excess dripping freely from the drain holes. Illinois says the same: use enough that water starts to drip out the bottom. A quick splash wets the top inch and leaves the lower roots dry.

Then check before watering again.

• Push a finger into the mix up to the first knuckle, as Penn State suggests. Illinois gives the rule: if the first inch or so is dry, water.
• Check daily in summer, and twice on the hottest days. Our guide to how often to water container plants in summer sets out the frequencies by pot size and weather.
• Water before plants wilt badly. Illinois advises watering before they show signs of severe wilting.

If you find a pot badly wilted, Penn State’s rescue sequence is to move it out of the sun first where that is possible, then give it a small amount of water. Dry mix behaves like a hard, dry sponge that will not absorb water until its surface is wet. For a small container, Penn State suggests putting water in a tray or saucer and letting the plant take it up from below.