Lettuce is one of the most popular vegetable crops in the United States. Part of the salad family, it is a leafy green that grows best in temperature in a range of 55-75 degrees. Though still able to grow in cooler temperatures, lettuce prefers middle ground climates and grows primarily during the early summer.
Lettuce requires a large amount of water, but is at high risk for being overwatered. This means gardeners have to be careful and accurate when watering their lettuce plants. Overwatered lettuce crops are susceptible to root rot, diseases, and pests. So, this begs the question, what do gardeners need to know about watering their lettuce?
How Much To Water Lettuce
Lettuce can be high or low maintenance depending on the climate and soil. Lettuce should have approximately one inch of water a week whether that water comes from watering or rainfall. In warmer weather more water can be used, up to 2″ of water a week.
This does not necessarily mean the lettuce only needs watered once a week, rather a consistent, but small amount of watering is recommended. Lettuce has shallow roots so the plant pulls water from the top layer of soil.
We use wunderground.com to get an idea of expected rainfalls and a rain gauge to get an accurate measure of rainfall.
How Often To Water Lettuce
Water lettuce plants 1-3x a week with anywhere from 0.25-1″ of water per week. Sandier soils and hot weather means gardeners should water the lettuce more often.
An inch of water in sandy soil can be as deep as ten inches, while an inch in clay soils only goes about six inches deep. Because of the short and shallow rootage of salad crops, sandier soils need more frequent waterings so the plant has access to water in the soil.
To check to see if lettuce needs more water, gardeners can take a trowel and dig into the soil. If the soil is only wet down one to two inches, give the lettuce more water until the dampness reaches a depth between three and four inches.
To help soil retain moisture, gardeners can add a layer of mulch to the top of the soil. This keeps any extra water from evaporating before the lettuce can access it.
Can You Overwater Lettuce
Yes, lettuce is a finicky vegetable with a shallow root system that needs a consistent supply of water, but also is susceptible to diseases, foliage rot, and soft growth if overwatered.
The overwatering issues are not just from the plant being given too much water, but also from the water sitting in poorly draining soil. Clay soils are more susceptible to holding water. Uneven lands can cause areas of the garden to pool water.
If you notice that the ground still has puddles of water 12 hours or so after watering you’ll most likely need to move your lettuce plants.
A drip irrigation system is recommended for gardeners growing lettuce. This type of system slowly drips water to the roots of the plants. These can be installed both above the ground or under the soil. This type of irrigation system also prevents pests such as slugs, aphids, and cutworms from breeding in the soil and destroying the lettuce from beneath the surface.
How To Water Lettuce Seedlings
For best production results, it is important to start lettuce seedlings indoors. This allows gardeners to control the seedlings’ environment and water amounts. Lettuce seedlings are very small and delicate. When the seeds are first planted, they are very lightweight and easily displaced. To avoid displacing the seeds when you first water them either before they’ve germinated or after, use a misting setting on a garden hose, or water the plants from the bottom tray of the pot.
Seeds take 4-10 days to germinate so continue this watering method until the plant is sturdy enough to withstand harder water. Seedlings are also sensitive to soil moisture and temperature, so if they are not germinating it is important to ensure that these factors are controlled and accurate.
Tips on Watering Lettuce
- Sprinkler System – A sprinkler offers an easy way to recreate rainfall on lettuce crops. This allows gardeners to ensure their lettuce is receiving enough water without causing an abundance of soil moisture that could lead to root rot or pest invasions.
- Drip Irrigation- This system drips water from alongside the lettuce keeping the foliage dry. This allows the water to drip down to their roots and slowly, but consistently waters the plant. The slow watering of a drip irrigation system keeps lettuce moist, but also prevents overwatering.
- Water Lettuce Seedlings From the Bottom – Watering lettuce plants from the bottom tray of their pots is one of the best ways to water seedlings. This keeps the delicate plant from being swept away in a large amount of overhead water and prevents puddling in the soil. Bottom tray watering also allows water to disperse at a slower, but more natural rate. This method of watering only works for seedlings. However, gardeners can switch to the furrow irrigation system after the seedlings have been transplanted.