Two Wests & Elliott's Gardening Guide To Growing Rosemary
Growing rosemary in your garden, in raised beds or in containers will not only provide you with a Mediterranean herb which you can use in your kitchen, due to it being an evergreen shrub it will add year round intertest to your garden which is enhanced when it produces it's dainty flowers.
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"I plant rosemary all over the garden, so pleasant is it to know that at every few steps one may draw the kindly branchlets through one's hand, and have the enjoyment of their incomparable incense; and I grow it against walls, so that the sun may draw out its inexhaustible sweetness to greet me as I pass." Courtesy of Gertrude Jekyll |
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When Growing Rosemary Which Varieties To Try
There are many different varieties of rosemary which you can grow, some are upright varieties and some are trailing varieties, some have flowers which are blue, pink, purple or white and some are more aromatic than others.
However, when it comes to growing rosemary from seeds, the only variety you seem to find is the common rosemary rosmarinus:
Rosemary ‘salvia rosmarinus’ – growing to approx. 3ft high and wide, this hardy evergreen has dark green, needle shaped leaves and will produce small, pale blue flowers. Can be sown sept to oct or march to may.
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Whilst you will find a much wider range of varieties available to you when growing rosemary from young plants or cuttings. Here are just a few varieties to try: Rosemary ‘Spice Island’ – a highly aromatic variety with short, dark green leaves and small blue flowers. Will grow to approx. 2ft high with a spread over 2ft 6in. |
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Rosemary ‘Majorca Pink’ – with aromatic foliage and semi-prostrate, this variety with short, dark green leaves and small blue flowers. Will grow to approx. 2ft high with a spread over 2ft 6in.
Rosemary ‘Gorizia’ – this larger variety will grow up to 5ft high and 5ft wide. It has short green leaves which are broad and needle shaped and will have small, light blue flowers.
Rosemary ‘Severn Sea’ – this is a good variety to grow over the edges of raised beds or large containers as it only grows to a height of approx. 16in yet will spread up to 3ft. It has striking small blue flowers and needle shaped, aromatic leaves which are dark green and short.
Growing Rosemary From Seed
Growing rosemary from seeds is less popular than starting from young plants simply because growing from seeds is a slow process, germination is often slow to start with and then it can take several years for your rosemary plant to be large enough for you to start harvesting from it.
However, starting from seeds will be more economical, so if you have the patience then it’s worth giving it a try. Just bear in mind that rosemary seeds can have a low germination rate – it can be as low as 30% - so you should sow more seeds than you would expect to plant.
Top Tip
You can improve the germination rate of rosemary seeds by soaking the seeds overnight in water before sowing. Use water from your hot water tap – you don’t want boiling hot water but neither do you want cold water, so nice warm water should suffice. And only soak overnight – if you soak seeds for too long they will ‘drown’ and not germinate.
If you want to get your timing right with rosemary – from sowing to planting out – then you will want to allow 10 to 12 weeks before the last frost date to sow the seeds indoors. However, as you must wait for the plants to mature before you can start harvesting, you could start the seeds off sooner and allow them longer indoors. But as always, consult the back of your seed packet for the supplier’s recommendation.
It’s best to use a seed tray – for which you have a clear cover – in which to sow your rosemary seeds, as fitting the lid will help to create a warmer, moister environment for the seeds to germinate in. Fill the seed tray with a good quality seed sowing compost (we always recommend sieving the compost to remove any lumps, for finer compost). Use a fine sprayer to moisten the compost and then gently press the seeds into the compost. Rosemary seeds require light to germinate successfully so they don’t need to be covered. Simply fit the clear cover over the tray.
You need to achieve a temperature of 18 to 21 degrees Celsius in order for the seeds to germinate – you will need to place the seed tray and cover in a propagator, on a warming mat or heated tray to lift the temperature so you will succeed.
As it can take up to 24 days for the seeds to germinate we recommend checking the temperature of the compost regularly to ensure it is getting warm enough – use a simple propagation thermometer which will allow you to easily check the temperature.
You also need to ensure that your seeds receive sufficient light to enable them to germinate successfully. Depending on where and when they have been sown may mean that you need to provide some supplementary lighting. This is now quite easy to achieve with the advances in grow lighting – so you could look to fit some LED lights on the cover of the propagator or some Secret Jardin LED grow lights suspended above the propagator.
Transplanting Your Growing Rosemary Outdoors
Rosemary seedlings should be grown indoors until they are at least 3 inches in height when they should be sturdy enough – as long as no frost is expected – to survive outdoors.
As your young seedlings will be used to the indoor conditions, it is important that you acclimatise them to the outside temperature by hardening them off – otherwise straight from the protected, undercover environment, to straight into your garden, could affect their continued growth.
When transferring rosemary outdoors it can be planted directly into the ground, into raised beds or into containers which are at least 12 inch in diameter. You just need to bear in mind that rosemary will only flourish in well-draining soil – so if your garden isn’t like that you are best to plant into a raised bed or container. When filling your container – which needs to have plenty of holes in the base for good drainage - use a soil based or multi-purpose compost, adding extra grit to ensure good drainage.
Also, rosemary will grow best with a soil pH that is slightly acidic to neutral – so around 6 to 7 – this is easy to check using a pH meter. When choosing the site for your rosemary look for somewhere that will get at least six hours of direct sunlight – this herb is really not suited to shaded areas.
When planting multiple plants, space them at least 18 inches apart. When transferring from pot to garden or container plant so they are the same depth in their new location as they were in their original pot.
Rosemary once established needs very little maintenance and is fairly drought tolerant. However, when establishing new plants you need to ensure they are watered regularly – although rosemary doesn’t like to have its roots sat in water, until its root structure is firmly established in its new location, it will need you to water more than you normally would.
Growing Rosemary In Your Garden Will Attract Beneficial Visitors
"As for rosemary, I let it run all over my garden walls, not only because my bees love it but because it is the herb sacred to remembrance and to friendship, whence a sprig of it hath a dumb language."
Courtesy of Thomas More
Rosemary will produce a mass of pretty flowers and it’s these that will attract a range of beneficial insects and butterflies into your garden, including:
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Growing rosemary will also deter some pests from your garden so it can be beneficial to plant some rosemary in your kitchen garden or at your allotment just for this reason. Rosemary has found to deter the following:
- bean beetle
- cabbage moth
- carrot fly
- flies and mosquitos.
Protecting Your Growing Rosemary
Growing rosemary is relatively easy as it attracts only a few pests and even those will cause very little damage.
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Rosemary Beetles – just like sage, rosemary will attract these shiny little beetles which are just 6-7mm long with metallic stripes on their bodies. Both the adults and the larvae will feed on the foliage and flowers of rosemary – although in reality they will cause very little damage to the plants as a whole so can be removed by hand. |
Scale insects – causing unsightly lumps and bumps on the plant, these scale insects suck the sap from rosemary which can both weaken the growth and result in black sooty mould appearing on the leaves of the plant.
Spittlebugs – cuckoo spit – cause a white, frothy looking mass on your plants with the immature spittlebugs inside the foam feeding on the rosemary. Although it doesn’t look nice it will not do any harm to established plants and can be washed off the plants with water.
Mealy bugs – small, soft bodied, sap sucking insects, mealybugs are usually found on rosemary plants growing indoors rather than outdoors where their predators keep them under control. They will affect the growth and vitality of rosemary plants but can be removed from plants with a jet of water.
Powdery Mildrew – resulting from infection by fungi, it is basically the powdery growth on the surface of the rosemary plant. It can weaken your rosemary plant but shouldn’t kill it. It’s easy to get rid of – one of the typical / traditional ways is to use a mix of baking soda, oil and dishwashing soap (not detergent) in water and spray the plant.
When Is It Time To Harvest Your Growing Rosemary?
When harvesting rosemary, as it it’s the sprigs of rosemary which you will use, you could harvest at any time of the year as rosemary is an evergreen herb. However, you will find that it is the new growth which has the best taste, so with this in mind harvest during spring on summer when rosemary is actively growing.
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You can identify the new growth as the leaves will be slightly lighter in colour. Try to harvest rosemary before its flowering as when you harvest you are encouraging the plant to put on more growth and prior to flowering it will put all it's energy into growing new leaves, so you will get a bigger harvest . Rosemary is a fairly tough herb so you will need a sharp knife, pair of scissors or snips when harvesting. |
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Ideally harvest rosemary - or any herb - early in a morning before the day warms up. You should cut sprigs around 4in in length - avoiding old wood as rosemary does not regrow well if cut back into old wood.
For best results only harvest what you are going to use at the time - if you need a lot of rosemary at once we would recommend cutting up to a maximum of 20-30% of the total plant - picking the sprigs so that you retain a good shape to the overall plant.
Why Spend Time Growing Rosemary?
Rosemary is a popular culinary herb, traditionally used when cooking lamb, chicken or game, as well as being used to add flavour to breads, biscuits and muffins.
Rich in vitamins – this includes vitamins A, C B6 and folate.
Contains minerals – including calcium, magnesium, iron, phosphorus, potassium, and copper.
Calories – 131 per 100g
Fat content – 5.8g per 100g
Protein content – 3.3g per 100g
Water content – 68g per 100g
In addition to it’s many uses in the kitchen, it has traditionally been used to treat a range of illnesses including headaches, insomnia, rheumatic pains through to helping with physical, emotional and mental well-being.
Our growing rosemary guide has been created from our personal knowledge, information gathered by speaking to other gardeners or manufacturers in the gardening industry, by reading gardening magazines and devouring information from books and the internet. We aim to be as accurate as we can, so if you find a mistake, please remember, we’re only human. if you have any queries you can contact us today!