Hello I’m Basil. I’m a Treecologist at Leaf & Limb and today we’re talking about watering your trees. The first, most important, step is proper planting. It will go a long way towards reducing your need to water. You want to choose tree species that suited to the area where you live so here in Raleigh, NC we have long hot summers. If you choose a species that needs a lot of water to begin with, you will be watering that tree every single day of the week. Species that do well here, that may not need as much water are the Eastern Redbud, the Tulip Tree or the Southern Magnolia — all great species.
Another important part of planting is to be sure your soil conditions are healthy. We recommend that you introduce mycorrhizal fungi when you plant your tree. Mycorrhizal fungi do occur naturally in soil, but it is best to jump-start the process if you can. These fungi form symbiotic relationships with a root system of a tree and they actually help a tree find water and nutrients in difficult to reach places. This is really good because this means that mycorrhizal fungi is helping you keep your tree watered and you don’t have to water as often.
A little planning can go a long way so take the time necessary to think about what you’re putting in the ground and how you’re doing it.
Now, let’s fast forward. You’ve planted your tree, now it’s time to start watering. What should you use to do this? We have some things that we like. We like soaker hoses, we like tree watering bags and we also like professionally installed irrigation systems. The reason these are good is they allow you to deliver water slowly over time which means the water can percolate down into the soil and get to the tree’s root system. If you don’t have any of these or you can’t afford them – no problem. Just use an open-ended hose or you can attach a spray nozzle to the end of your hose.
When you begin watering, you want to spray the root ball for a newly installed tree and you also want to spray the area right outside of the root ball. This really encourages new root development. For a more established tree, you’re going to want to spray the ground from the trunk all the way out to the edge of the canopy, which we call the drip line.
In general, we recommend approximately 10 gallons per inch of trunk diameter. Let me break that down for you. If you have a trunk that is 2 inches wide, you’ll want to give that tree 20 gallons of water per week. So again, the rule of thumb is 10 gallons per inch of trunk diameter, per week. What does that mean? It’s going to be different based on whatever hose you’re using or whatever system you’re using. If you’re using an open-ended hose, it might be something like 5-7 minutes every other day. It just depends.
We all know that weather is unpredictable. We might have a lot of rain or not enough; it might get really hot or really cold. You may need more or less water.
Here are some tricks to see whether or not your tree needs water without worrying about a regimented water schedule. First trick, go and dig up a little bit of soil from underneath the canopy of your tree. If it’s very dry and blows away in the wind, you tree needs some water. If it’s very wet and goopy and muddy, it’s oversaturated. Don’t add any more water. What you’re looking for is soil that has some moisture. It holds its form, but it’s not dry enough to blow away and it’s not wet enough to be muddy in your fingers.
Another trick is to just look at your plant. A healthy tree will have green, vibrant leaves in the summertime. If it’s dry, they could be yellow or they could be wilting or curling. This means your tree probably needs some water. Worse yet, if the tree leaves and turning brown and cracking; your tree is VERY thirsty. The most extreme situation would be leaves are actually falling off, twigs are splitting, and branches are splitting. Your tree is in trouble. It may actually be too late.
Last, but not least, spend some time with your tree. The more you’re out there. The more you see what it looks like in different conditions — after a rainstorm or on a hot summer afternoon – you will begin to develop a sense for a when that tree is thirsty or has sufficient water simple by looking at it.
I hope this information was helpful. I’ll post a few links below for a few things that I think will help you. Please, send me questions or comments. I’d love to help if I can.
Remember: healthy trees, happy people.