How to Care for a Rosemary Tree

By Erin Marissa Russell

Rosemary trees are a common holiday gift for gardeners, home cooks, and those new to caring for plants alike. These little trees are easy to care for and make a handsome addition to the home or outdoor garden as well as being easy to put to use in the kitchen. But if you’re receiving a rosemary tree for the first time or have cared for one unsuccessfully in the past, you’re probably wondering how best to care for your rosemary tree. We’ve got you covered with this guide to keeping your rosemary tree in top condition throughout the year.

Prune Your Rosemary Tree as Needed to Maintain its Triangular Shape

When you first receive your rosemary tree, its shape will be well defined, but as it grows, the edges will get shaggy and uneven. Every three to four weeks, use clean, sterilized shears to clip off the branches that are out of bounds. Trim the branches back all the way to where they meet the trunk of your rosemary tree. If you leave a small piece of the branch behind, the tree can become stressed trying to care for it, so make sure to clip the branches as close to the trunk as possible. After you’ve pruned your rosemary tree, mist it with a spray bottle full of water.

Find the Right Location for Your Rosemary Tree

Your rosemary tree needs plenty of sunshine to stay healthy. You can either keep it indoors in a sunny windowsill year round or move it to the outdoor garden when the weather is warm enough. A south-facing window is normally the best indoor spot for a rosemary plant, as long as it doesn’t get too hot. 

Just make sure that the spot in your outdoor garden where you place your rosemary tree has soil that drains well, if you’ll be removing the tree from its container and planting it in the ground. This plant even loves to grow in sandy soil, but it won’t tolerate too-wet soils that keep its root system wet. And even outdoors, rosemary needs a spot with full sun—that’s at least six to eight hours of sunlight each day. It can stay in the outdoor garden from the spring to the fall season. 

Rosemary also requires good air circulation, so whether it’s indoors or out, make sure that your rosemary plant isn’t too sheltered from the wind or cramped against other plants that will keep air from circulating around it. Whether you keep your rosemary plant in its container or put it in the ground, it will need to come back indoors before the first frost in your area, so you’ll need to put it into a container if it’s been growing in the ground. More on that in the next section.

If You Keep Your Rosemary Tree Potted, It Will Need a Larger Container

If you move your rosemary plant into the outdoor garden permanently, it will be happy to grow in the ground and keep getting larger. But if you keep it in the pot, eventually the plant will need to be upgraded to a larger container. Every year in spring, choose a container that’s the next size up from the one your rosemary plant is currently growing in. Signs that a rosemary plant is ready for a new container include if the plant has recently broken out in lots of new growth or if you just can’t seem to get the plant well hydrated enough.

Gently remove the plant from its current container. Fill the new container about halfway full with potting soil, then place the plant inside the new container on top of the new soil. Use more potting soil to fill in around the edges of your rosemary tree, making the soil firm enough that the tree will stand up in place securely. Water the plant deeply (until the moisture drips from the container’s drainage holes) as soon as you are done repotting it.

You can avoid the need for larger containers and keep your rosemary tree at the same size instead if you prefer. To do this, you’ll need to prune the roots of your rosemary tree, slicing off a few inches from the root ball of your plant, both at the bottom and the sides. Then simply place the rosemary tree back in its current container and re-pack the soil around it.

Keep Your Rosemary Tree Well Hydrated

Rosemary plants can be harder than others to keep well watered, as rosemary won’t droop, wither, or show other signs that it is low on water until the situation is really dire. Although rosemary plants are tolerant of drought, they will still need some watering from the gardener. The basic guideline is to water your plant deeply once every week or two. Watering a plant deeply means watering until the moisture drips from the drainage holes of the container. If your plant is growing in the soil outdoors, leave the water on near the base of the plant until the moisture has soaked several inches into the soil. However, don’t water your rosemary tree again until the soil where it is growing is dry to the touch. Rosemary plants are sensitive to their root system getting too wet when the soil they grow in is waterlogged. Soil that stays too wet can lead to root rot, so you want to be sure to let the ground dry out between your watering sessions.

Bring Your Rosemary Tree Indoors During Cold Weather

Rosemary trees are tolerant of hot weather and high temperatures, and they also perform well in a wide range of humidity levels. However, weather that gets too cold can be fatal for these plants. Rosemary is usually hardy until the temperature reaches 30 degrees Fahrenheit (-1.1 degrees Celsius). That means that before the first frost arrives in your area, you’ll want to remove your rosemary tree from the outdoor garden and bring it back indoors. If it has been growing in the ground, you’ll probably need to get a larger container for the plant than it used the previous year at this point. If you repotted your rosemary tree in the spring and have kept it in its container while it was outdoors, then all you will need to do is move the tree inside when the weather cools down.

Give Rosemary Trees a Boost in Spring with Fertilizer

In the springtime, it’s a good idea to feed your rosemary tree with a fish or kelp emulsion to help foster lots of new growth and keep your tree healthy. Every once in a while, you can also spray your rosemary tree with the same fertilizing fish or kelp emulsion to keep it growing strong. It’s an especially good idea to do this if you notice that your tree is looking a little under the weather.

These few guidelines are all you need to know to take good care of your rosemary tree and keep it in excellent shape. Even if you move your rosemary tree into the outdoor garden, if you maintain its watering and pruning schedule, you should be able to put the rosemary tree back into its container when next Christmas rolls around so you can bring it back indoors. Some people use their rosemary trees as miniature Christmas trees. If you do this, just be careful not to use lights that get too hot (large lights tend to do this) or to keep your tree too near to candles or other Christmas decorations that can cause fires. You can get more details about caring for your rosemary plant in our article How to Grow Rosemary Herbs at Home.

Learn more about growing rosemary trees in containers:

https://bonnieplants.com/how-to-grow/growing-rosemary/

https://www.gardeningknowhow.com/edible/herbs/rosemary/rosemary-christmas-tree.htm

https://plantcaretoday.com/rosemary-plant-care.html

https://www.thriftyfun.com/How-to-Care-for-a-Rosemary-Tree-1.html