When growing lettuce in the garden, we typically anticipate a fresh, firm head of lettuce composed of numerous, bright green leaves. However, this is not always the reality. Many gardeners are instead presented with a limp head of lettuce with wilting leaves. So why does garden lettuce wilt and how can it be fixed?
The most common reason for lettuce to wilt is due to a lack of water. When lettuce isn’t receiving enough water, its leaves will begin to wilt in an effort to conserve water that would’ve otherwise been evaporated off of its leaves. If left unaddressed, wilted lettuce can have stunted growth and also become susceptible to disease.
While insufficient water is the most common culprit of wilted lettuce, there are a number of other causes for lettuce wilting as well. However, with the proper care and treatment, wilted lettuce can be quickly revived and also easily prevented.
Why is my Lettuce Wilting?
Lettuce can wilt for many different reasons. These reasons include:
- Insufficient Water
- Excessive Water
- Excessive Heat
- Lettuce Drop
- Septoria Leaf spot
As stated earlier, insufficient watering is the most common reason for lettuce to wilt. Lettuce can go without water for a few days, however, after about a week or so of little to no water, lettuce will begin to wilt and show signs of drought stress.
When lettuce undergoes drought stress, its most prevalent symptom is its wilting leaves. Because there is a lack of water throughout the plant, the lettuce leaves lose their rigidity and therefore wilt as a result.
Wilting is also a survival mechanism for lettuce as well as many other plants. When lettuce wilts, it allows the leaves to minimize their surface area exposure. In turn, this reduces the loss of water that would have been evaporated from the lettuce had it not wilted.
Reviving your Wilted Lettuce
In addition, to wilting, a lack of water can also cause lettuce plants to have stunted growth and become more susceptible to disease. However, a quick watering will revive most drought stricken lettuce plants.
In order to keep your lettuce from wilting, it is important to keep up with watering. Aim to keep the surrounding soil of your lettuce consistently moist but not soaking wet. In most cases, this only requires you to water your lettuce a few times a week. However if the surrounding soil is dry, watering is recommended.
While a lack of water can cause your lettuce to wilt, excessive amounts of it can also have the same effect. When lettuce is overwatered, the roots aren’t able to breathe. In turn, they will die and begin to rot.
Once root rot begins, it will cause the leaves of your lettuce plant to turn yellow and wilt. If left untreated, root rot will kill your lettuce plant.
Treating Overwatered Lettuce
Once your lettuce plant develops root rot, they easiest option would be to harvest any unaffected leaves and discard the rest of the plant.
If you really wish to save your lettuce however, carefully uproot the entire plant from the soil and pry off the infected roots. Roots that are affected by root rot will be mushy and have a black or brown color to them. Additionally, these roots will be decaying and may easily wither off the plant.
After you have removed all the infected roots, rinse off any dirt or soil still attached to the clean, uninfected roots with running water as the soil may be harboring fungus that causes root rot.
Once you have rinsed off the soil, replant your lettuce back into your garden using some well drained (but not soaking wet) soil.
Given that lettuce is a cool season crop, it is more sensitive to warmer weather compared to other plants. Lettuce grows best in temperatures between 60° to 65°F (15.5°to 18.3°C). However, if temperatures start to surpass 80°F (26.6°C), lettuce will begin to wilt.
Excessive heat will dry out the soil much faster as well thus causing more harm to your lettuce. In addition, your lettuce will likely bolt if it continues to experience warmer temperatures.
Protecting your Lettuce from the Heat
While lettuce is easily affected by warmer temperatures, there are some simple ways to protect against the heat and keep your lettuce from wilting.
One of the most effective ways of shielding your lettuce from the heat and help keep it cool is to employ the use of shade covers. Shade covers are one of my favorite options for helping lettuce as well other garden plants keep cool in the hot summer months as they are highly effective at doing so while still allowing essentials like water and sunlight to pass through.
Shade covers come in countless different sizes and shapes depending on your needs. Additionally, shade covers also come in several different intensities depending on how much shade you need. When it comes to shading lettuce, a 50% shade cloth is ideal.
Another way you can protect lettuce from the heat is to plant it earlier in the season. As stated earlier, lettuce is a cool season crop so it should be planted a little bit earlier than the rest of your vegetables. In fact, lettuce can actually germinate in temperatures as low as 40°F (4°C).
For more information on protecting lettuce from the heat, check out my article: How Much Sun Does Lettuce Need? | Too Much Can be Bad
One of the most common diseases lettuce is affected by is lettuce drop. Caused by the fungus Sclerotinia, this disease wrecks havoc on lettuce plants and may be the reason why your lettuce is wilting.
Lettuce affected by lettuce drop can have many different symptoms. These include:
- Wilting of the leaves
- Rotting brown leaves
- Decaying of the crown tissue
Treating Lettuce Drop
If your lettuce is showing signs of lettuce drop, the best thing to do is to harvest the unaffected leaves and discard the rest. Next, apply a fungicide around the remaining lettuce plants to help stop the spread.
Additionally, crop rotation is highly recommended if your lettuce experiences leaf drop. The Sclerotinia fungus can remain in the soil long after you harvest your lettuce even if fungicide is applied.
Septoria Leaf Spot
Another disease notorious for causing lettuce to wilt is septoria leaf spot. Like lettuce drop, it is also caused by fungus that dwells in the surrounding soil when conditions are ideal.
Common symptoms of septoria leaf spot on lettuce include:
- Wilting of the leaves
- Small grayish-brown lesions on the leaves
- Yellowing leaves
Treating Septoria Leaf Spot
When it comes to managing and treating septoria leaf spot, the procedure remains pretty much the same as it does for leaf drop. Harvest what you can from the infected plants and discard the rest followed by an application of fungicide around the remaining lettuce.
When it comes to preventing fungus borne diseases, avoid watering your lettuce from overhead and overcrowding your garden as moist overcrowded environments make it ideal for these types of funguses to develop.
Other steps that can be taken to reduce the chance of disease are:
- Minimizing weeds
- Crop rotation
- Mulching around your lettuce
Hopefully by now you know why your lettuce is wilting. While lettuce most commonly wilts because it is thirsty, it also does so when it is receiving too much water, heat or in the event of a fungal disease such as leaf drop or septoria leaf spot.
By identifying the cause of wilting lettuce early on, we can better address the problem and in turn, produce fresh, firm heads of lettuce composed of numerous bright green leaves instead of limp, soggy heads of lettuce with wilting leaves.