Underwatering
Plant disorder
Description
Underwatering is a shortage of water available to a plant’s roots. It occurs when rainfall or irrigation fails to replace water lost from soil and leaves, or when water runs off or drains through before moistening the root zone. Plants growing in containers, shallow or sandy soil, and hot, windy sites are especially vulnerable. As cells lose water, leaves and young stems lose firmness and wilt. Continued stress can cause curled leaves, dry brown edges, slowed growth, dropped leaves, and fallen flowers. Severe or prolonged drought may damage roots and kill the plant. Symptoms vary with the species, its stage of growth, and the weather: a plant may wilt only during the hottest hours at first, then remain wilted overnight as the shortage worsens. A thirsty plant can also have wet surface soil if water has not reached its deeper roots, so the moisture of the root zone matters most.
Symptoms
- Wilting
- Curled or cupped leaves
- Brown or crispy leaf edges
- Yellowing leaves
- Stunted growth
- Leaves dropping
- Flowers or buds dropping
How to Identify
Check the soil where the roots are, not just at the surface. Push a finger into container mix or use a trowel to inspect several inches down in a bed; an unusually light pot also suggests dry mix. Underwatered plants often perk up after thorough watering, although badly damaged leaves may not recover. Wilting in midday heat alone is not proof: if soil is moist and the plant recovers by evening, temporary heat stress may be responsible. Overwatering and root rot can also cause wilting, but their root zones stay wet; affected roots may be brown and soft. Inspect for pests or stem damage if moisture seems adequate.
Prevention
Water according to the plant’s needs, weather, and soil rather than a fixed daily schedule. Check moisture below the surface and irrigate when the root zone begins to dry, before plants show persistent wilting. Apply water slowly and deeply enough to reach the roots; for containers, water until excess drains out, then empty any saucer so roots do not stand in water. Recheck pots during hot or windy weather, when they can dry quickly. Add organic matter to suitable garden soils to improve water retention, and use a layer of mulch to reduce evaporation, keeping it away from stems. Group plants with similar water needs, choose drought-tolerant plants for dry sites, and make sure newly planted specimens receive close attention while their roots establish.
Treatment
First, confirm that the root zone is dry. Water slowly at the soil surface, allowing it to soak in rather than run off. If a container’s mix has become so dry that water runs down the sides, water it in stages or briefly soak the pot until the mix is evenly moist, then let it drain completely. For plants in the ground, apply water over the root area and check afterward that it reached the needed depth. Move a potted plant out of harsh afternoon sun temporarily if practical, and add mulch after watering to slow further drying. Do not keep the soil constantly saturated in an attempt to compensate. Wilting leaves may recover within hours; dry, crispy tissue will not. Remove dead material once the plant has stabilized, and pause fertilizer until growth resumes. If the plant stays wilted despite moist soil, investigate root rot, heat stress, or other causes.
Plants Affected
Not sure this is your problem? Try the problem diagnoser.