How to grow rosemary in Perth

Rosemary (Rosmarinus officinalis) is a shrub with evergreen, needle-like leaves and white, pink, purple, or blue flowers, native to the Mediterranean region, rosemary thrives in Perth’s Mediterranean climate. This delightful herb is an all-star in the kitchen and is a great option for raised garden beds, containers, in-ground gardens as well as hedging plant.

A workhorse plant, rosemary demands very little to grow successfully. If you have ever wondered how to grow rosemary in Perth then look no further. Rosemary is a simple herb to grow, but there are still a few tricks to successfully growing rosemary in Perth, Western Australia. Get these right and you will be laughing.

When to plant rosemary in Perth:
The best time to plant rosemary in spring once all chances of frost have passed. It can be planted successfully at other times of the year, but it’ll need a little more care to protect it from the elements.

Where does rosemary grow best?
Rosemary grows best in full sun: the more sun and heat, the more intense the aroma and flavour will be. Ideally you should plant in a location with free-draining soil, but rosemary is adaptable to virtually any soil except wet or waterlogged, so slightly drier soil is preferable.

Rosemary will tolerate very high, alkaline soils with a pH of 7.5 or greater. Also worth noting rosemary can tolerate our windy coastal conditions, but will need shelter from particularly cold wind.

How much water does rosemary need?
Rosemary doesn’t like too much water. It thrives in Western Australian summers when it is hot and dry. If there is a long, dry spell and the plant starts to look dry and thirsty then be sure to water it, but it generally does better with a little less water.

Is rosemary a perennial?
Yes, rosemary is a perennial and once it is planted once, you find your rosemary, growing back year after.

Types of rosemary in Australia:
There are a number of varieties of rosemary in Australia. I like to divide them into three sub-categories, cooking varieties, cold climate varieties and ground cover varieties of rosemary.

Best rosemary varieties for cooking
There are no bad choices when it comes to picking rosemary varieties for culinary use. Generally speaking, taller vertical plants produce the strongest flavours.

• Spice Island rosemary – A very flavourful Rosemary and also a very beautiful shrub. It stands very erect and grows to about four feet and is covered with dark blue flowers in late winter and early spring. Named for its exceptional flavour as a culinary seasoning either fresh or dried.
• Tuscan Blue rosemary – Classic fragrant Mediterranean herb, rosemary is well suited to seaside plantings and dry areas. Tuscan Blue is bold, tall, very upright; with clear blue-lilac flowers through the warmer months. Makes an aromatic hedge.  Perfect for focaccia bread and roast lamb.
• Blue Spires rosemary – This hardy evergreen rosemary variety it has unique light grey-green needle foliage. Blooms clear blue flowers in spring on a semi-erect shrub. Thrives in poor well-drained soil. Full sun recommended for best growth and flowering results.

Best varieties of rosemary for ground-cover

• Huntington Carpet rosemary – As its name suggests, Huntington carpet is a rosemary variety which grows close to the ground. As it has narrower leaf nodes, it appears denser than some other varieties. This makes it ideal for slopes and covering slopes and walls.
• Prostratus rosemary – Is a variety which grows around 2 feet tall and up to 8 feet across. It blooms with pale blue flowers and is popularly used to accent walls. When planted on an edge, it cascades beautifully. The densely packed leaves offer good coverage without appearing messy or unkempt.

Best rosemary varieties for colder climates
If you live in the south-west of Western Australia you might nee a cool climate rosemary.

• Salem rosemary – This variety comes from New Zealand and is sometimes called the Christmas Herb, due to its pine fragrance. The aroma is quite mild compared to some other varieties, but the oil production is high. It is a prized culinary variety because the flavour is strong, but not overwhelming.
• Hill Hardy Rosemary –  is a wonderful, cold tolerant Rosemary that loves sun and needs little watering. Upright and robust, this aromatic herb has a pleasing flavor and fragrance for cooking and soaps.  It can withstand temperatures lows of at least 0°

When to prune rosemary Australia?
Prune rosemary back just before summer, to open up the plant and minimise disease.

A good tip with pruning rosemary is to use some as cuttings. Rosemary grows equally well from cuttings and from seed.

How to grow rosemary from cuttings:
Rosemary is easy to propagate from cuttings taken in summer from the new growth. It is often said you should not buy a rosemary plant but wait to be given one from a friend to give longevity to a relationship.

1. Between December and January, cut off a stem that’s about 10-15cm long and remove the bottom half of the leaves – this helps to focus new growth on the roots, rather than leaves.
2. Use a sharp knife or scissors to cut the stem just below a leaf node, which is the point where a leaf was growing.
3. Place the stems into a glass of water and wait for roots to form, dipping them into a hormone rooting powder will speed up the process but is not required.
4. Fill a circular pot with a good quality potting mix and place rosemary cuttings around the edges, leaving at least an 2.5cm between them.
5. Water and then place into a plastic bag to keep in the moisture. If you have a propagator, you can use it instead.
6. Gently remove the plants and soil from the pot after a couple of weeks. If each plant has a root system, you can then separate them into individual pots filled with a loam-based potting mix.
7. Keep you new rosemary plants indoors or in a greenhouse and water regularly. The plants will be ready to plant outdoors the following spring.

How to grow rosemary from seed:
Growing rosemary from seeds is easy, fun and rewarding! In general growing rosemary in pots is a great idea. Below are the steps on how to how to grow rosemary in a pot from seeds.

1. Rosemary seeds take a long time to germinate so aim to start growing them in indoors or in a greenhouse in mid-winter.
2. Fill seed trays with a soil-less potting mix, like vermiculite. Sprinkle three seeds into each cell. Rosemary doesn’t have a high germination rate so putting in two or three seeds increases your chances of success.
3. Sprinkle a thin layer of seed raising mix over the seed tray cells and mist with water until moist.
4. Cover your seed trays with plastic to keep moisture and warmth in, which will help the seeds to germinate faster.
5. Leave the plastic on – only removing to spritz the soil with water when it dry’s out – Remove once you see your seedlings pushing up through the soil, which can take up to 25 days.
6. Once your rosemary seedlings reach 7.5cm high, you can move into individual pots filled with a loam-based compost.
7. Keep indoors or in a greenhouse and water regularly, moving into larger pots as and when needed. The plants will be ready to plant outdoors the in the spring once the last signs of frost have passed.

What’s the best fertiliser for rosemary?
Rosemary doesn’t need a lot of fertiliser if the soil is rich in composted organic manures. However, it will benefit from an a dose of fertiliser in the spring and summer months to provide all the ongoing essential nutrients for balanced plant health. A Dynamic Lifter Soil Improver and Plant Fertiliser will encourage flowering during spring.

When to harvest rosemary:
Once your rosemary plants are established, you can harvest all year round. Cut what you need from the bush using secateurs or scissors. If your plants are still small, then remember to leave enough leaves for the plant to keep growing as leaves are important for plant photosynthesis.

How to store rosemary:
Rosemary is best when used straight from the plant. However you can keep your rosemary fresh in the refrigerator.  Simply wrap your rosemary sprigs in a damp paper towel and place it in a zip lock bag. Seal the bag and place it in the crisper of your refrigerator. This should keep it fresh for up to three weeks.

Companion plants for rosemary:
The best companion plant for rosemary is broccoli as both plants benefit from being planted together. Planting rosemary nearby will also help your broccoli, beans, cabbage, carrots and chillies to flourish. The only herb we found that would benefit from rosemary companion planting was sage.

Rosemary plant care and common problems:
Rosemary are fairly tough plants but can be attacked by  pests like aphids and whitefly. In humid climates, rosemary is susceptible to fungal diseases, like powdery mildew. Trimming stems and branches regularly to improve light and air circulation will help reduce the risk. If any leaves are affected, cut them off and throw them in the bin.

Check out our other how to grow in Perth guides:

• Grow broccoli in Perth
• Grow carrots in Perth
• Grow chillies in Perth