Salvia plants rarely produce viable seeds so, the most common way of growing salvia is from cuttings taken from a “mother” plant.
Since salvia is a perennial plant, it will grow year after year, as long as it is not exposed to freezing temperatures. Its leaves are normally emerald green and are covered with a fine coating of short airs, that give the leaves a velvety look.
Salvia plants can grow very tall and most of times they will need support. One particularity of salvia plants is that, when the branches grow high enough and bend, or break, they might root if coming in contact with moist earth. You can cut the top of the plant. You will have a cutting for a new plant and the “mother” plant will bush out.
How to take and root cuttings
If you have already a salvia plant and want to make cuttings to grow more plants or give it away to friends you can do it by doing a cutting with 10 to 20 cm from the plant. The cutting should be done just below a node since it´s more likely that roots will develop from there.
The cuttings should be made with clean and sterile shears/knife to prevent attacks from germs or fungi that can cause stem rot. After you make the cutting you can either root it in water or in soil.
Some salvia growers say that the branches that fall from the plant spontaneously (normally during summer) will have a higher successful rate than the one cut from the plant.
Rooting in water is fairly easy. You should place the cutting immediately after being cut in a glass with water. It should be non chlorinated water so, either boil your tap water (and let it cool down) or get distilled water. Each cutting should be put alone in one glass with about 3 cm of water. Place somewhere where it gets filtered sunlight and change the water daily. The rate of success of rooting in water is about 75% and in 2 weeks the roots will start to develop. When the roots get about 3 to 4 cm long it is time to transplant the plant to a pot.
Rooting in soil will require some more material than rooting in water:
- potting soil
- disposable plastic cups
- rooting hormone (you can get on your local grow shop)
- one 3 litre food storage bag
- rubber band
- water
Poke some holes in one of the plastic cups and fill it up two thirds with the potting soil and open a small hole in the soil of about 4 cm deep. Take your cutting from the plant and clean it from the bigger leaves, leaving some small leaves on top. Clean the stem of the cutting with water immediately after cutting it and, keeping it wet, place into the rooting hormone (2 cm above the cut). Shake off the excess rooting hormone, place the cutting in the hole in the soil and gently put soil around the cutting. Water the plant until there is water running off the drainage holes in the cup. Get a small stone or piece of wood and place it inside the second cup and then place the cup with the plant inside it. This will allow enough drainage space. Use the bag to place the cups inside it and close it with the rubber band. This will maintain moisture for the plant so, there is no need to water it frequently. After some weeks the plant is ready to be transplanted to a bigger pot.
Growing Salvia Outdoor
The best conditions for salvia plants are:
- few hours of partial sunlight or shade;
- cool place;
- humid place.
Outdoors, salvia will thrive in a humid semi-tropical climate. It must be well watered and have a soil with good drainage and high humus content.
Even though very hot and sunny locations are not the best for salvia, it is still possible to grow them with the use of a automated misting system that will go off every hour or at least 3 times a day. Also a shade net might help to protect salvia for direct strong sunlight.
If you want to grow salvia on a colder and dryer place it might still be possible but, you will need to give the plant a bit extra care. Make sure you get some protection for frost, water the plants frequently, and mist when the humidity gets low.
If where you live it gets below 5ºC in winter, the best option is to grow salvia in containers that you can move indoors when it is too cold. That way, you will grow salvia outdoors in summer and indoor in winter.
Rich soil with good drainage is essential for salvia plants to thrive in any environment. When choosing containers they should be the biggest possible and have drainage holes on the bottom. You can add some gravel on the bottom of the containers to help good drainage and help preventing root rot.
Growing Salvia Indoor
Indoors and with proper care, salvia can be grown anywhere in the world.
Salvia will do well indoors placed by a window. If you have a toilet with good natural light it might be a good place to have the plant, as the humidity of the shower will good for the plant.
If you place the salvia by a window that gets full sun that can be ok, as long as you keep it well watered and misted frequently.
If you have the chance, take the plant outside when it is warm enough. Let the plant get some rain to help prevent a high concentration of mineral salts in the soil.
If you want to move the plants to a new environment, especially with different light and humidity, do it gradually. Salvia plants are adaptable but, they need time to get used to new conditions, as they do not like extremes changes in the environment.
Pests and Problems
If you are buying a cutting, usually the biggest problem with salvia cuttings occur within the first weeks after receiving it because salvia does not like big changes in its environment. So give it good care and keep an eye for its behaviour to be able to correct watering, lighting, humidity, soil quality.
If you have doubts about watering do not worry, salvia will show you when it needs water. The leaves will droop and you should water it at the first signs to prevent all the plant from getting limp.
Salvia, as all other plants can be attacked by many pest. When growing in a greenhouse a special attention as to be paid to whitefly.
Salvia can be attacked by scale insects and aphids that can be removed from the leaves with a cotton swab with alcohol.
If you have a lot of slugs around your garden you can prevent them attacking the salvia by growing the plants in containers in a raised deck (or something that put a bit higher from the ground).
Root-rot can set in if the plant is not well watered. To prevent this make sure to water it correctly and ensure good soil drainage.
Spider mites can be solved by spraying dissolved Castile soap in water to spray de leaves, on top and under. The spraying should me made 3 times with 2 weeks intervals. Do over due the soap so not to damage the leaves.
The good old fashioned garden hose can be one of your best tools to keep the pests away. You can spray de leaves with it somewhat hard but, not hard enough that you are damaging the leaves.
How to harvest and dry salvia leaves
When harvesting the leaves you should do it in a way that does not cause too much stress to the plant.
If you are growing indoors you can harvest some leaves once in a while, dry them and stored them up.
When growing outdoor, the plants are usual bigger and they will handle better and leaves can be picked every so often.
Growers that want to harvest a big quantity of leaves usually wait until October/December, for the end of growing season before the plant starts flowering. At that time they harvest a lot of leaves and leave the plant during the winter (in a non-freezing place). This is usually the method used for large scale producers. If you are aiming at your own personal use you can pick leaves once in a while, dry them and keep them in a sealed container away from light. The leaves stored this way will be good and maintain their potency for many years (it is not known exactly how much storage time it will take for the leaves to loose the potency.)
So, to dry leaves for a future use there are some options:
Nature´s way: wait until the leaves naturally fall from die. Gather the leaves and put them in a tray in a room with low humidity leaves, turning them often. This has the advantage of not causing stress to the plant but, on the other hand, you have to wait until the plant loses naturally the leaves.
Drying as tobacco: pick big leaves and place them on top of one another. Cut the pile to make strips of about 0,5 cm. Pile them up in a plate and turn 2 times a day until they are dried. Some say that like this the smoke will be smoother. Leaves dried like this might not keep as long as thoroughly dried leaves.
Using a food dehydrator: dry the leaves until the leaf stems are crispy and snap with pressure. This method is fast and thorough, you only have the cost of buying a food dehydrator.
Using a conventional oven: place the leaves in a tray and leave them at no more than 75°C until they are crispy. This method is fast and convenient even though it can be hard to keep the oven at the desired temperature range.
Using a microwave oven: place the leaves in a tray in a single layer between 2 paper towels and start to dry at high temperature 10 seconds at a time checking each time if they are dried.
Calcium Chloride (CaC12) drying: it is possible and the leaves will be efficiently dried. However implies that you buy CaC12. The leaves can never touch the CaC12 and you will need to use a polyethylene container. You need to put the CaC12 on the bottom of the container, put a aluminium foil over it without touching it, and then the leaves on top of the foil. Seal the container and check it in 2 days. The leaves should be dry by then.
Independently of the drying method used, the dry leaves should be stored in a sealed jar, preferably glass like a mason jar, and kept away from light. The leaves will retain the potency for some years.