Summer Tree Care: What You Need to Know

If water is life, then mulch is a lifesaver! When we talk about tree care in the summertime, we are mostly talking about the one-two punch of watering and mulching. Below you’ll find a round-up of some simple tips for summertime tree care.  

BE WATER-WISE 

Before you start watering, make a plan based on the trees you have. Answering these questions can help you make a watering plan that works. 

• How old are your trees?  
• How much water will they need?  
• How do you tell if you’ve watered enough?  
• When should you water?  
• When should you not?  

How can I check if my tree needs to be watered?  

Easy! Feel it with your hand. Dig down into the soil a few inches and squeeze with your hand to feel if it is wet, dry or somewhere in-between.  

How much water do I use?  

If your tree is young and still establishing, it will need a little more TLC, so shoot for 15-20 gallons, every 2-3 days. After your tree becomes established (it usually takes a two-inch caliper tree 2-3 years to establish), you can reduce the watering frequency. However, we still recommend following the 10 gallons of water per inch caliper of the tree, watering when we experience long periods without precipitation and throughout the winter. Allow soil to dry between waterings and continue to monitor your soil moisture to determine when your tree needs to be watered.  

How can I make sure water reaches deeper into the soil? 

A simple hose is the most basic tool needed to water your tree, but soaker hoses, soft spray nozzles and soil needles can help break through the soil surface. Most absorbing tree roots are found in the first 12-inches of soil depth; apply water slowly so it has time to absorb into the soil and reach these vital roots.    

How can I tell how much water my tree is getting through my hose or irrigation system? 

You can determine your hose’s output by taking a container of known quantity, like a gallon jug or five-gallon bucket, and setting a timer for how long it takes the hose to fill up the container at a trickle. Then you can calculate how long you should trickle your hose to achieve a certain quantity of watering. Irrigation systems themselves generally do not provide enough water for young trees during their establishment phase, so plan on giving supplemental water as well and checking the soil moisture regularly.  

What else?  

As travel begins to pick back up and Denver residents start hitting the road, don’t forget to make a tree care plan while you’re gone. When possible, ask a neighbor, family member or friend if they’ll water for you and you can offer to do the same for them. And remember to check with your utility department for preferred times, right-day usage and other potential temporary changes.   

MULCH-MUSTS 

Mulch: it does so much! Keeping a mulch ring around young trees keeps them safe from mower and string trimmer damage, which can be an easy point of entry for pests and disease. It also holds moisture in and protects against temperature extremes. It decomposes and adds nutrients to the soil, too! 

Here’s how it’s done:  

Apply wood chips, bark, or other organic mulch 2 to 4 inches deep in a ring around the base of the tree, but at least 3 inches away from its trunk. Mulch reduces soil evaporation, improves water absorption, insulates against temperature extremes and can break down over time, adding necessary nutrients to the soil. Make sure to replenish your mulch as necessary, at least a few times a year.  

We said MULCH, not rocks or grass.  

Rocks as “mulch” are bad for trees. They retain heat, causing the soil temperature to rise and that increases evaporation. Plus, rocks don’t provide essential nutrients and can actually change the soil chemistry, which can be unfavorable for many trees. They’re not all bad, though – rocks and xeriscape lawns can be a way to conserve water in other areas of your garden, but it is essential that the area with your tree roots is covered with mulch or other organic material.  

For different reasons, grass around the base of the trunk is also not recommended. Why? Because grass is greedy. It competes with young trees for moisture and nutrients in an already water-scarce climate. Plus, having grass close to your tree increases the risk of mechanical damage to the trunk from lawn mowers or string trimmers.  

Vertical Mulching 

For those of you ready to graduate from Mulch 101 and really dig into the topic, we present vertical mulching. Vertical mulching can alleviate soil compaction, which jeopardizes tree health and is commonly found in Denver in areas with clay soil or recent construction. Vertical mulching improves soil conditions and allows for deeper water penetration. Yep – it’s all related. It’s accomplished by removing columns of poor-quality soil around the tree in a radial or grid pattern, and then filling those columns with compost. You can watch this video for more information.  

TREE VITALITY = EARTH VITALITY  

We hope that all these tips help you determine how much water each of your trees need, what type of mulch to use and why it all matters. Because when done correctly, these steps can increase tree vitality, which can help your trees stay healthy year-round and keep our urban canopy in great shape for the future.