Tree Care: Summer Watering

You have a new tree!

This is the beginning of a very long and beautiful friendship.

Congratulations!

Photo: Mature northern red oak in the woods of Druid Hill Park

Care for your tree and it will care for you (and future generations!):

Depending on its species, a tree will live for a few decades or up to a few centuries and provide ecological, social and economic benefits the whole time. Proper maintenance within the first two years after planting is vital to the long-term health of a tree. There are several ways you can help your leafy friend become established in its forever home.

Why do we need to help?

Trees in a natural forest setting can survive on their own. So why do we need to water our urban trees? As we all know, Baltimore’s hot, humid summer days can be brutal! Higher temperatures due to global climate change & the urban heat island effect lead to increased stress for both human & plant communities – so a little extra care goes a long way. Nursery grown trees go through shock when they are removed from their plastic pots and transplanted into the ground. It takes about 2-3 years for most trees to develop the extensive root systems needed to soak up ample water. Watering is the most important factor for tree survivability. Be sure to keep it up all summer!

Photo: YouthWorks team member, Matt, watering young trees at REACH! Partnership in Clifton Park

How to water:

Where?

Water directly around the base of the tree trunk and as wide as the root ball (2-4ft). There is no need to water the leaves. If your tree is mulched, be sure to wet the mulch ring because it acts like a sponge and holds water longer. For tips on proper mulching, check out our mulch blog.

When?

Water your tree immediately after you plant it. After that, water weekly first thing in the morning. Evening watering is also okay but avoid watering during the heat of the day. Afternoon watering increases evaporation and chance of disease.

How much?

A young tree requires 20 gallons of water per week between May and October for at least the first two summers after planting. (You can also split this up and water 10 gallons twice a week.) It is important to note that rain is only a substitute for watering if we have a one inch rain storm or more!

Flow rate?

Baltimore’s soils have high clay content and are often compacted due to development. Water as slowly as possible to allow for maximum root absorption. Slow drip watering provides small quantities of water directly to the root zone. It allows for deep infiltration so water can reach 8-12 inches into the ground instead of just wetting the surface. This encourages deeper root growth, which leads to a more anchored mature tree.

Deep-infiltration watering methods:

There are multiple ways for you to ensure that deep infiltration occurs.

Garden hose:

Turn your garden hose on low and place the hose head next to the tree trunk for 15-20 minutes. Make sure you set a timer so you don’t forget to turn it off! Note that over-watering can also harm the tree.

There are also a couple of ‘slow release’ watering products available that do the work for you.

Gator bags:

You may have seen ‘Treegator bags’ around town – these green plastic sacs are zipped around the trunk. Fill them with water once or twice a week depending on the bag capacity. Over a period of hours, the water will slowly drip out from holes in the bottom of the bag:

Photo: BWB staff filling up a gator bag after a tree planting in West Towson

GreenWells:

At Blue Water Baltimore, we recently started using hard plastic watering rings called ‘GreenWell Water Savers’ that are installed around the tree trunk when the tree is planted. These can be ordered online. The base of the GreenWell buried by two inches of soil to hold water. Just fill it up and watch the water slowly sink into the root ball:

5-Gallon Bucket Method:

For a DIY version, you can drill 4-5 small holes in the bottom of a 5-gallon plastic bucket. Place the bucket next to the tree trunk, fill it up and let the water drip slowly to the thirsty roots. (Or drill holes in the lid and turn the bucket upside down.) Move the bucket around the root zone to reach all areas. This method allows you to know exactly how much water you’re providing!

Photo: Fill two 5-gallon buckets twice a week to give this young river birch exactly what it needs – 20 gallons!

How can you tell if your tree needs water?

Pay attention to local weather reports & rainfall accumulation. Have we had a lot of code red days in a row recently? Are we in a drought? Your tree probably needs some H20! You can check our recent local rainfall accumulation here.
Keep an eye out for browning/wilting/curling leaves or premature fall coloring. This is an indication that your tree is stressed. However, note that some trees can be suffering from drought but show little or no obvious signs, so sticking with routine watering is best.

Want to save water?

Worried about increasing your watering bill? Consider installing a rain barrel at your home to hold & store up to 60 gallons of rain water. Check out our blog post for more details!

Photo: Hand painted rain barrel at St Luke’s on the Avenue in Hampden that is used to water the nearby native plant garden

Weekly Watering Reminders

Check out this great weekly watering reminder from Casey Trees in DC. Baltimore has generally similar weather patterns and this is a useful resource to determine if your trees need a drink!