Planting & Caring For Rosemary Plants

When planted right and in the right spot, Rosemary plants are very easy-to-grow in garden beds and containers. 

Here's a breakdown of what you need to know...



Cultural Preferences



Soil Preferences

Rosemary grows well in most any somewhat loose, moist to somewhat dry soil of average to low fertility. As with so many other plants, constantly soggy or wet soil can cause root rot and other harmful plant diseases. So make sure to plant in well-drained soil!


Testing Soil Drainage

If you are uncertain about soil drainage in the area you intend to plant, it's well worth taking the time to test the drainage before planting. 

To test soil drainage, dig a hole 12" wide by 12" deep in the planting area. Fill the hole with water and let it drain. Then, after it drains, fill it with water again, but this time clock how long it takes to drain. In well-drained soil the water level will go down at a rate of about 1 inch an hour. A faster rate, such as in loose, sandy soil, may signal potentially dry site conditions and possibly a need to add some moisture retentive organic matter. A slower rate indicates poor draining soil and is a caution you need to improve drainage, plant in a raised mound or bed, or look for plants that are more tolerant of wet or boggy conditions.



Soil pH Preference

Rosemary grows and flowers best in a moderately acid to slightly alkaline soil ranging between 6.0 to 7.5 on the pH scale. Most average garden soils fall between a pH range of 6.0 to 7.0. 


Testing Soil pH  

Soil pH is a measurement of the alkalinity or acidity of soil and is measured on a scale of 1-14, with 7 as the neutral mark. Any measurement below 7 indicates acid soil conditions, and anything above 7 indicates alkaline. If you're unsure about the pH of your soil, or whether or not it's suitable for growing Rosemary, it's a good idea to test the soil pH in the planting area. 

You can quickly test soil pH with an inexpensive soil pH tester probe. To raise the pH (make more alkaline) you can add pelletized limestone to the soil. To lower the pH (make more acid) you can apply Soil SulfurAluminum Sulfate, or Chelated Iron. Adding organic compost to the soil or using compost as mulch can also help to increase acidity and maintain acid soil conditions. 




Light Preference

Rosemary grows best in full to mostly sun, however will tolerate a few hours of light shade or filtered sun during the day.



How To Plant A Rosemary

Scroll down for container planting instructions


Step 1

Start by digging your planting hole at least two to three times as wide and no deeper than the root ball. The wider the hole the better. Place native soil removed from planting hole around the perimeter of the hole, in a wheel barrow, or on a tarp.


Step 2

Depending on the type, fertility and porosity of the soil in the planting area you might consider amending the native soil. When planting in dense clay or other compacted soil it is beneficial to thoroughly mix in some good organic matter, such as bagged top soil, sand or small gravel, and/or a good planting mix at a 50/50 ratio with the native soil. When planting in very sandy, quick-draining soil consider mixing in some bagged top soil to help retain moisture. When planting in a loose, moist but well-drained soil of average to low fertility there is no need for adding a soil amendment.


Step 3

To remove your Rosemary plant from the container it was growing in first squeeze the sides of the pot. Then, grasp the base of the plant with your fingers and try to very gently lift and remove the root ball from the container container. Then, carefully loosen some feeder roots around the surface of the root ball. 


Step 4

To plant, set your plant in the planting hole so that the top edge of the root ball is at or slightly above ground level to allow for settling. If necessary, add some backfill soil mixture to the bottom of the hole to achieve proper planting height. 

NOTE: If the soil in the planting area is poorly drained (constantly soggy or wet) improve drainage or select a different plant species more tolerant of wet soils.



Step 5

After setting your Rosemary plant in the planting hole, use one hand to hold the plant straight and your other hand to begin back-filling your soil mixture around the root ball, tamping as you go to remove air pockets. When you have filled the hole to the halfway point you can soak the soil. Then continue back-filling to the top edge of the root ball. To avoid suffocating your plant, avoid placing any soil on top of the root ball.


Step 6 (Optional)

When planting far from a water source and in well-drained soil, you can use remaining soil mixture to build a 2-inch high water retaining berm (catch basin / doughnut) around the outside perimeter of the planting hole. This basin will help to collect water from rainfall and irrigation often reducing the need for hand-watering. The berm can be removed after a growing season or when the plant is established.


Step 7 

Next, deeply water the planting area, including the root ball, to a depth equal to the height of the root ball. For an extra boost, to stimulate early root formation and stronger root development you can also water you new plant with a solution of Root Stimulator, which reduces transplant shock and promotes greener, more vigorous plants.


Step 8

Spread a 1- to 2-inch layer of shredded or chipped wood mulch or pine straw around the planting area to conserve moisture and to suppress weed growth. As the mulch decomposes it will add vital nutrients to the soil that your plants will appreciate. Avoid the use of freshly chipped or shredded wood for mulch until it has cured in a pile for at least 6 months, a year is better. Avoid placing or piling mulch directly against the base of your plant as this could cause the bark to rot.



How To Plant A Rosemary In A Container


When growing in pots, Rosemary appreciates a consistently moist but well-drained soil. Constantly soggy soil can and often will cause root rot or other harmful or deadly plant diseases. Therefore, I highly suggest using a container with a drainage hole(s) and a quality potting soil or potting mix, or a 50/50 combination thereof. To ensure good drainage consider adding 10 to 20% perlite or pumice to the soil mixture. 

As mentioned, make sure to choose a container with drainage holes at the bottom and also one that is large enough to allow for 2 to 3 years of growth before shifting up to a larger size container. This might mean your planting pot would be 8 inches or more in width than the root ball of your plant. 

Container color will matter as well. Not only will you want to pick a color of container that goes well with the flower and foliage color of your Rosemary, you'll also want to pick a container that matches the style of your home or other structures and other plants in the surrounding environment. 

Many nursery & garden centers offer a wide variety of containers to choose from. Before heading out to buy a container take pictures of your home and the surrounding environment. Doing so will help you to choose just the right color and style.


Container Planting Instructions

Step 1

Before filling your container with the soil mix, we recommend lining the bottom with shade cloth or a porous landscape fabric. This will keep the drain holes from becoming stopped up with soil. If you place gravel or other materials in the bottom of the container lay the fabric over it. 


Step 2

To remove your Rosemary plant from the container it was growing in first squeeze the sides of the pot. Then, grasp the base of the plant with your fingers and try to very gently lift and remove the root ball from the container container. Then, carefully loosen some feeder roots around the surface of the root ball. 


Step 3

Pour a small amount of your soil mixture in the bottom of the container. Set the plant in your container and make necessary adjustments by adding or removing some soil so that the top edge of the root ball will sit 1/2 to 1" below the rim of the container.



Step 4

Backfill with your potting soil around root ball, tamping as you go, until the level of potting soil is even with the top edge of root ball.


Step 5

Water thoroughly until water starts to drain from the holes in the bottom of the container. Add more potting mix if settling occurs during watering.


Step 6 (Optional)

Apply a 1/2" layer of wood chips or sphagnum moss to soil surface to help conserve moisture. 





How To Care For Rosemary Plants

Feeding - Watering - Pruning


How To Fertilize A Rosemary

Rosemary are very light feeders however will benefit from light fertilization. Feed in late winter or early spring with a slow-release shrub & tree type fertilizer or an organic plant food. To avoid stimulating new growth that could be damaged by an early frost, cease fertilization two months prior to the first frost date in your area.


Soil pH

Rosemary grow best in a moderately acid to slightly alkaline soil ranging from 6.0 to 7.5 on the pH scale. Most average garden soils fall between a pH range of 6.0 to 7.0. 


How To Test Soil pH  

Soil pH is a measurement of the alkalinity or acidity of soil and is measured on a scale of 1-14, with 7 as the neutral mark. Any measurement below 7 indicates acid soil conditions, and anything above 7 indicates alkaline. If you're unsure about the pH of your soil, or whether or not it's suitable for growing Rosemary, it's a good idea to test the soil pH in the planting area. 

You can quickly test soil pH with an inexpensive soil pH tester probe. To raise the pH (make more alkaline) you can add pelletized limestone to the soil. To lower the pH (make more acid) you can apply Soil SulfurAluminum Sulfate, or Chelated Iron. Adding organic compost to the soil or using compost as mulch can also help to increase acidity and maintain acid soil conditions.





How To Water A Rosemary

Rosemary are quite drought tolerant when established, however will require water to become established. They do not like constantly soggy soil, which can lead to root rot and other plant diseases. So be careful not to overwater them!


Tip:  When watering with an automated irrigation system it's best to set your timer to water during the early morning hours and not in the late evening or at night, which can lead to the onset of fungus and other foliar diseases. During the first few weeks after planting, check soil moisture often and adjust irrigation time if necessary to keep the soil moist, not wet. 



At Planting Time 

Immediately after planting deep soak the soil in the planting area, including the root ball, to a depth equal to the height of the root ball. For an extra boost, you can water your new plant with a solution of Root Stimulator, which stimulates early root formation and stronger root development. Root Stimulator reduces plant shock and promotes greener, more vigorous plants.


During the First Active Growth Season

In average garden soil you should not have to water your newly planted Rosemary every day. More often than not, this causes soggy soil conditions that can lead to root rot and other plant diseases. In the absence of sufficient rainfall, water only as needed to keep the root ball and surrounding soil damp to moist. 

Keep in mind that deep soaking less frequently is much better than splashing just a little water on the plants every day. Shrubs planted during the winter dormant season, when plants are not actively growing and evaporation is much slower, will require much less water. So, be extra careful not to overwater during winter!


Thereafter

When established, Rosemary are very drought tolerant plants. Only during prolonged periods of summer drought will plants require supplemental irrigation. If you see leaves discoloring (becoming lighter in color) or falling from the stems during a dry period this could be an indicator your plants could use a good deep soaking.




How To Prune A  Rosemary

Rosemary do not require pruning, however respond very well to it for shaping purposes and to harvest and use for culinary purposes. 


During the Active Growth Season

Rosemary is an herb extensively used in cooking. If you are not pruning it regular to harvest the stems and leaves, and you want to control the growth and keep the plant more dense, you can prune lightly throughout the growing season. Make sure when you are pruning to NEVER prune to a point beyond the older, woody stems. Take off no more than 5 inches at a time. 

Note:  Cease pruning of Rosemary 6 to 8 weeks prior to the average first frost date in your area.


Hard Pruning In Late Winter

Rosemary plants respond well to a hard pruning in late winter or very early spring, when the plant is not actively growing. When pruned in winter, the plant grows back in spring looking better than ever. At this time, you can cut back a rosemary to about half it's size/height. Avoid pruning beyond a point on a stem where there are no leaves. 


Tree Forming and Topiary

If you start when the plant is young, Rosemary can be pruned into a small tree or various shapes. The most popular shapes are cone or pyramid and globe. 

To form a small tree, as the plant grows, simply cut the shoots off the bottom of the main stem/trunk. As the growth continues the growing tips of the other stems should be snipped off. This will encourage lateral growth and you will soon have a very bushy top. The plant can be left to grow naturally or be trimmed back once it reaches the ideal size.

 



Plant Long & Prosper!

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