Growing Rosemary

Rosemary with Flowers Birds Eye View

Rosemary is a great herb to grow in your garden. It is resistant to some pests so you don’t have to worry about it too much, and it can be harvested year-round in most areas.

In order to successfully grow rosemary for yourself, it is important to know the climate in which you live, as the plant has certain needs that vary from region to region.

In this guide, we’ll cover what you need to know to grow your own rosemary.

Planting rosemary seeds

If you are starting your rosemary from seed, the timing of your planting will be a bit different. Aim to plant the seeds with enough time for them to germinate, sprout and mature before you plant them outside.

For rosemary, this time period takes a bit longer than most herbs. Rosemary is a slow grower, so you should aim to plant seeds 3-6 months prior to when you plant to grow the rosemary plants outside.

If you don’t have the patience for that, you might consider growing your rosemary plant from cuttings.

To plant the rosemary seeds, purchase some potting soil and fill a container or tray with the potting soil. It doesn’t have to be a deep container — even a shallow tray will be fine for rosemary seeds. 

You can purchase plastic pots or packs to plant them, or use something you have lying around your home, such as an egg carton.

Once the container is full of potting soil, poke a hole in the soil with your finger no deeper than the first joint in your finger. Then, place the rosemary seed in the hole and cover it up lightly with potting soil.

To initiate the seed’s growth, water the rosemary seed lightly.

Try to keep the soil in direct sunlight as much as possible. You can cover it with some clear plastic to keep the humidity high as well. 

Make sure to keep on watering the soil lightly whenever it dries out. The soil doesn’t need to be more than damp, but it does need to be moist consistently for the rosemary seed to germinate.

You’ll soon start seeing a baby rosemary sprout emerging from the potting soil.

Transplanting rosemary seedlings

After the rosemary sprouts, you’ll want to let it grow a little bit to establish a root structure. If the seedling is planted with its own space to grow, you won’t need to transplant it until it grows its own root cube. 

However, if the rosemary seed was planted with other rosemary seeds in its own space, it should be planted earlier so that its roots aren’t in competition for limited space.

As long as the roots have room to grow, you’re fine to keep the rosemary in its container. 

If you notice that the rosemary seedling is drying up fast, this may be a sign that it’s time to plant it in a larger container. You can transplant a rosemary however many times you’d like before planting it in its final destination.

To transplant a rosemary, pinch the bottom of the container as you gently pull the sprout up. If the seedling is very small, you can turn the pack upside down as you do this for each sprout so that the plant and its early root structure fall out into your hand. 

If the rosemary is rootbound, meaning that the roots are tightly wound together forming the shape of whatever container it was in, then you’ll want to gently rip the roots apart once before transplanting the rosemary into its next container.

After you have transplanted your rosemary, water it in and make sure it gets some sunlight for continual growth.

Planting rosemary outside

Whether you are growing your rosemary from seed, or you purchased a young rosemary plant from a local garden center or greenhouse, eventually you’ll want to plant it outside (rosemary plants can get too big as a house plant).

To plant your rosemary, gently squeeze the bottom of the container and pull the plant out of its pack.

Then, use a trowel or your hand to remove soil from where you’d like to plant it. 

If the soil is hard and packed down, consider using a tiller to break it up, or just push a shovel in the soil a few times to break up the clumps.

Best soil type for rosemary

You can check your rosemary plant’s tag for specific information regarding soil needs.

Most rosemary plant varieties grow best with well-drained soil.

You may need to mix in some potting soil or other soil additives to get your soil to the ideal consistency.

When to plant rosemary outside

Choosing when to plant rosemary outside is an important consideration. If you plant them too early, there’s the risk of a late frost killing them off if the plants are young and tender.

As a general rule of thumb, typically if you wait until after Mother’s Day you’ll be fine to plant rosemary outside. That being said, in Central PA we have had late frosts later than Mother’s Day, so make sure to check the forecast for your area in the spring to make sure that there isn’t a deep frost on the horizon.

In some cases, planting rosemary outside before Mother’s Day is definitely doable. Some annuals are just hardier than others, so you’ll want to consider the hardiness of your rosemary, too.

It depends on the plant’s size, maturity, hardiness (did the greenhouse you purchased the plant from “harden it off”?), and spring weather.

Where to plant rosemary

Once you have your rosemary, you’ll need some soil and a spot to plant it. If you’re going to be planting it directly outside from the pack you purchased it in, you have the option of planting the rosemary in the landscape, in a hanging basket, or in a pot. Rosemary will do great in any of these locations.

Sunlight requirements for rosemary

If your rosemary receives too little or too much sunlight exposure, it will likely still live, but may not grow as abundantly and could require more care.

Rosemary plants will grow best in full sunlight, so make sure they will get at least 6-8 hours of full sun exposure wherever you plant them.

There are general sunlight requirements for all rosemary. For specific sunlight requirements for the variety of rosemary that you purchased, make sure to check the plant tag.

Best temperature and humidity for rosemary

Most areas have plenty of temperature swings, so an easy way to determine if your growing area will work for rosemary is to check your USDA growing zone.

A rosemary will grow well in most USDA growing zones, but the length of its season will vary depending on the region. In some areas, rosemary plants can be grown as a perennial.

Watering rosemary

One of the most important factors in keeping your rosemary looking healthy is to diligently water the rosemary plant throughout the summer. 

For rosemary, you’ll know they need water when the top inch of soil is dried out. To check, you can stick your finger into the soil down to the first joint in your finger. If it’s moist, no need to water the rosemary plant. If it’s dry, you’ll want to water it in.

Be careful that you don’t overwater the rosemary. A rosemary plant can be susceptible to diseases if it gets too much water. 

If you planted the rosemary in a container, make sure that it has holes in the bottom for excess water to escape. Otherwise, the water can collect at the bottom of the container and cause root rot, or other diseases.

Fertilizing rosemary

Another important factor for plant health is keeping your rosemary fed with nutrition.

If the rosemary is planted in the ground, you can lessen the amount of fertilizer it’ll need by building up the soil with compostable material in the year(s) leading up to your planting. Otherwise, you’ll want to fertilize the rosemary throughout the summer. 

A good rule of thumb for fertilizing rosemary is to give the plant a water-soluble fertilizer every third watering. This rule helps to account for the change in temperature and weather throughout the season. For example, in May you won’t be watering your rosemary plant as much as in the heat of the summer in August. So feeding the plant every third watering helps to provide rosemary what it needs throughout the season, no matter the weather conditions.

It’s also recommended to plant the rosemary with a slow-release form of fertilizer to feed the plant slowly throughout the summer. You can add this in with your potting soil in a pot.

Growing rosemary in a hanging basket

If you’re growing rosemary in a hanging basket with other herbs, you’ll want to make sure you don’t overfill the basket with plants. Plants will generally fill in the space you give them, so if the hanging basket isn’t packed full when you first plant it, that’s great.

The more rosemary you plant in your hanging basket, the more you’ll need to water the hanging plants. In general, if more plants compete for water and soil, it’ll take more maintenance to keep the hanging basket looking beautiful.

If you’re watering your rosemary in a hanging basket, you can check if it needs water by lifting the basket from beneath. If the basket is noticeably light, it could use some water. 

You’ll know you overwatered your rosemary in a hanging basket if water comes dripping or streaming out the bottom of the basket where the holes are.

Growing rosemary in a pot

As mentioned above, be careful you don’t plant too many rosemary in a flower pot.

The answer for how to care for rosemary grown in a pot will vary according to the size of the pot. In general, make sure that it has plenty of room to grow and has adequate sunlight exposure where the pot is placed.

A rosemary that is planted in a container, whether it’s a pot or a hanging basket, will need to be watered more than rosemary grown in the landscape, since they won’t be able to pull natural water from the ground.

When we pot our rosemary plants, we typically stick to just one rosemary plant per pot. You’ll be surprised by how much these plants bush up!

Growing rosemary in the landscape

Choosing rosemary for your flower beds or other landscaping is a great choice. They make for great borders and can help add beauty to your yard.

Since you’re planting them in a permanent spot, you’ll want to be extra careful when planting rosemary in the ground outside. Ensure that there’s little chance of frost and that the rosemary is in a spot that matches their sunlight needs.

If you do have a late frost, and your rosemary is already in the ground, you can cover them overnight with a bucket or sheet to protect them in most cases.

Rosemary blooms

Rosemary plants will produce light lavender, pink or blue blooms if you let them.

This means these plants can attract bees and hummingbirds.

Pruning rosemary

Cutting back or pruning your rosemary can be healthy for the plant. You shouldn’t need to do this more than a few times throughout the summer. It can be good to do this if the plant is overgrowing its area, or overpowering another plant in a container.

Common diseases for rosemary

A rosemary is more susceptible to common diseases, such as downy mildew or root rot when it isn’t cared for properly. That being said, even rosemary that is given the correct care can fall victim to some diseases.

Consult with your local garden center if you notice that your rosemary has a disease.

Overwintering rosemary

A rosemary acts as an annual in Pennsylvania, meaning that it lives for one growing season and then dies. In other areas that are warmer, like down south, it’ll grow fine outside through the winter.

If you’d like to save your rosemary plant overwinter, you can pot it up and place it somewhere where it’ll receive plenty of sunlight inside. Depending on how large the rosemary plant has grown, this may not be an option.

Pest control for rosemary

Typically, natural predators are enough to take care of bugs and pests that eat at your rosemary. For example, ladybugs will eat aphids and can help control them.

However, in some cases, you will need to take extra measures to kill off plant pests. Again, consult with your local garden center for a specific solution to your pests.

Companion plants for rosemary

There are many other plants that grow great with rosemary. These are what we would call “companion plants.” This means that if they are planted together they will generally complement each other with their colors and growing styles.

When looking for companion plants for your rosemary, look for plants that have similar growing needs. This is an easy way to find plants that grow well. For example, if two plants love the sun, require similar fertilizer needs and one is taller while the other is a spreader, they will probably be great companion plants in a pot or hanging basket.

Varieties of rosemary

There are many varieties of rosemary. In general, their growing needs will be consistent across these varieties, but it’s always best to check the plant’s tag to make sure there aren’t specific instructions for your variety of rosemary.

Some common varieties of rosemary plants are:

  • BBQ rosemary
  • Spice Island rosemary
  • Blue Lagoon rosemary

Propagating rosemary

It’s possible to propagate rosemary

To do so, you can cut off a small piece of the plant and put it in water for a week or so. Soon, the rosemary should start growing fine roots.

Eventually, you’ll be able to plant the rosemary cutting into the soil and care for it like you would a normal rosemary plant.

Please note: propagating rosemary may not be possible if the stems have become “woody.” Make sure you cut sprigs that are the plant’s new growth.