Tree Bark Cracking? Here’s What It Could Mean | Lancaster Tree Doctor
Cracked bark can be natural or a warning sign. Proper care helps keep trees healthy.
If you’ve ever walked past a tree and noticed the bark splitting or peeling back like an old book spine, it can be a little unsettling. Is something wrong with the tree? Is it dying? Or is this just what trees do?
In Lancaster, CA, with our dry climate, hot summers, and chilly desert nights, cracked bark can show up more often than you’d expect. Sometimes it’s part of a tree’s normal aging process. Other times, it’s a red flag that something’s wrong.
Let’s dig into the most common reasons bark cracks, when you should worry, and what you can do to help your trees stay healthy and strong.
Why Does Tree Bark Crack?
Cracked bark can come from several causes, some harmless, some not. Here are the main culprits:
1. Natural Growth and Expansion
As trees grow, they expand outward. Think of it like a kid outgrowing a shirt – at some point, the shirt stretches, pulls, and finally splits. That’s what can happen to bark. In fast-growing trees or younger specimens, the bark can’t always keep up. This is especially true for species like sycamores or eucalyptus, which shed bark as part of their natural growth cycle.
This kind of cracking tends to be vertical, shallow, and evenly spaced. It usually doesn’t cause harm and is simply a sign that your tree is growing like it should.
2. Temperature Swings (Sunscald and Frost Cracks)
This one’s a big deal in the Antelope Valley. We’re used to those hot sunny days followed by chilly nights. That’s tough on a tree’s outer layers.
During the day, sunlight warms the bark, especially on the south and southwest sides. At night, temperatures drop quickly, causing the outer layer of bark to contract faster than the inner wood. This rapid change creates stress fractures in the bark – often called “frost cracks” or “sunscald.” You’ll notice vertical splits, sometimes a few feet long.
Thin-barked trees like ash, maple, and certain fruit trees are more vulnerable. Cracks from sunscald often show up in winter but don’t become obvious until spring.
3. Drought Stress
We don’t need to tell you that Lancaster gets dry. Extended drought or inconsistent watering weakens a tree’s internal moisture balance. When a tree is dehydrated, it can’t maintain healthy bark tissue. This can lead to dry, brittle bark that splits and peels, especially during periods of high heat.
Signs of drought stress include wilting leaves, early leaf drop, smaller foliage, and of course, cracking bark.
4. Physical Damage
Sometimes the cause is right in front of us. A lawn mower bump. A curious dog. Kids playing with sticks. Even strong winds or a low-speed vehicle impact can damage bark and lead to cracking.
Once the bark is compromised, it creates an entry point for pests, fungi, and rot – so even minor damage is worth paying attention to.
5. Insects and Disease
Certain pests and pathogens are especially sneaky. Bark beetles, borers, and other insects chew their way under the bark, damaging tissue and leaving it weak and cracked. Fungal infections like cankers or wood rot can cause peeling, blistering, or oozing bark.
These aren’t just cosmetic issues. Left untreated, they can kill branches or even the entire tree.
When Is Cracking a Problem?
Not all bark cracking is a crisis, but there are signs that indicate something more serious is going on. Call a certified arborist if you notice any of the following:
Cracks that circle all or most of the trunk
Bark peeling off in large sheets
Sticky sap, oozing liquid, or foul smells
Soft, discolored, or sunken wood under the bark
Fungal growth, like mushrooms or mildew, on the bark or roots
Dead or dropping branches near the cracking site
Insect holes, sawdust piles, or webbing on or around the trunk
A single shallow crack might not be cause for alarm, but several of these signs together mean your tree could be struggling with pests, dehydration, or internal decay.
How to Help a Tree With Cracked Bark
So what do you do if your tree’s bark is splitting?
1. Water Wisely
Proper watering is one of the best things you can do. In Lancaster, the rule is deep, infrequent watering. That means soaking the root zone slowly and thoroughly, then waiting a few days before watering again.
Don’t let the soil stay soggy – that’s just as harmful. Mulch (more on that next) can help the soil hold onto moisture without getting waterlogged.
2. Mulch to Protect and Nourish
Add a two- to four-inch layer of mulch around the base of your tree, but keep it a few inches away from the trunk itself. Mulch acts like insulation – it regulates soil temperature, retains moisture, and reduces weed competition.
Organic mulch like shredded bark, compost, or wood chips is ideal. In our dry climate, this small step goes a long way toward keeping trees happy.
3. Protect From Sunscald
Especially for young or thin-barked trees, wrapping the trunk during winter can reduce the risk of sunscald. Use commercial tree wrap or plastic tree guards, but be sure to remove them in spring so they don’t trap moisture or pests.
Also, try not to prune too aggressively during hot months. Exposing previously shaded bark to full sun can increase the chance of damage.
4. Avoid Injury
This one’s simple but often overlooked. Keep lawn equipment away from trunks. Don’t tie things to your trees (yes, even hammocks). Keep pets from gnawing or scratching the bark. The fewer wounds a tree has, the better its chances of staying healthy.
5. Call a Certified Arborist
If cracks are deep, spreading, or accompanied by signs of illness, it’s time for a professional inspection. Arborists can assess the damage, recommend treatments, and help you make a plan to protect your landscape.
Tip Top Arborists has been serving Lancaster and the surrounding area for decades. Our certified experts know how to spot early warning signs and take action before your tree’s health declines.
Why Bark Cracking Matters
Bark isn’t just tree skin. It’s a vital layer that protects the inner structure, carries nutrients, and helps the tree regulate its health.
When bark cracks, it opens the door for everything from pests to rot to water loss. Minor cracks can heal over time if the tree is otherwise healthy, but deeper splits or repeated damage can weaken the entire structure.
Think of cracked bark like a wound. If it’s clean, small, and you take care of it, it might heal on its own. But if it’s deep, infected, or left alone too long, it can spread into something more dangerous.
The Bottom Line
Cracking bark isn’t always bad, but it’s never something to ignore. In a place like Lancaster, where weather extremes, drought, and intense sun are the norm, our trees face constant stress. Learning what to look for – and when to act – can make all the difference.
If your tree’s bark is cracking and you’re not sure why, it’s better to be safe than sorry. Tip Top Arborists offers free consultations to assess the health of your trees and recommend smart, practical solutions to keep your landscape safe and beautiful.
Need a second opinion or just want peace of mind?
Give Tip Top Arborists a call. We’ve been keeping Lancaster’s trees in tip-top shape since 1976.