Planting tips for salvia

For hardy salvia (those which can spend all winter outside) :
 
This group includes European salvia, many oriental salvia, some American salvia and many of the salvia from China and Japan. 
 
In our climate these varieties  are generally planted in full sun although some of the varieties from the far east prefer semi-shade.  If possible choose a spot which is sheltered from the wind.  The soil needs to be well drained, stagnant humidity is one of their worst enemies.  Most varieties will suffer more from excess water than from drought, they are more likely to drown than die of thirst.  Natural rainfall is quite sufficient for their needs.  Although a certain amount of humus is advised, excessive organic matter is to be strongly avoided.
 
There is no need to add fertilizer.  Pruning after growth has started in the spring just to remove dead wood or to give the plant an attractive shape.
 
 
For hardy shrubby salvia :
 
This group includes all shrubby salvia of the salvia microphylla group (s. chameadryoides, s. lycioides, s. greggii, etc.).  However it does not include the salvia officinalis group (s. fruticosa, s. heldreichiana, s. libanotica, etc) since, although these are also shrubby and hardy, they require different care and growing conditions.
 
These salvia will withstand sufficiently low temperatures to remain outside in winter except possibly in those regions where temperatures regularly drop below -12°C.  If this is the case in your garden then you can overcome the problem by planting along a south-facing wall or by protecting them with fleece during the coldest periods.  These are the plants responsible for salvias’ image as low maintenance plants, flowering non-stop from spring into autumn.
 
They need a sunny location and if possible one which is sheltered from the wind.   Soil needs to be well drained, stagnant humidity is one of their worst enemies.  Most varieties will suffer more from excess water than from drought, they are more likely to drown than die of thirst.  In dry regions occasional watering will be necessary during summer drought to maintain flowering, otherwise they’ll make do with natural rainfall.  Although a certain amount of humus is advised, excessive organic matter is to be strongly avoided.  There is no need to add ferlilizer unless the plants are grown in pots, in which case prefer a fertilizer with higher potassium and phosphate, and lower nitrogen levels.
 
Wait until the end of March to prune and then cut the plants back by at least ½ to 2/3 of their height.
 
 
Salvia from desert regions :
 
This group includes varieties from a part of California and the north of Mexico, most of the African species and some of the orientals.  They withstand winter cold but are very sensitive to excess humidity.
 
In our climate they need to be planted in full sun with very good drainage.  In those areas with a Mediteranean climate they need no watering other than natural rainfall.  In wetter regions they need to be kept relatively dry once growth has slowed.  It is important to avoid excessive organic matter.  Only add fertilizer if the salvia are grown in pots.  The only pruning needed is a minimum to remove dead wood, carried out once growth has started in the spring.
 
Container growing allows the plants to be protected from excess rainfall.  Use a well drained, low fertilizer compost and water with a weak solution of fertilizer during the growing season.  Hardiness is always relative and it is always worth trying different spots in your garden to see if these salvia can be grown in open ground all year.
 
Non-hardy, summer flowering salvia:
 
This group includes varieties which will not support being left outside in winter, mainly salvia from America.
 
They may be planted outside whilst all risk of frost is past (not before May, and in some areas the end of May) and will flower all summer, some continuing until the first frosts.  They generally prefer full sun to part shade and prefer to be sheltered from the wind.  Soil needs to be well drained, stagnant humidity is one of their worst enemies.  Most varieties will suffer more from excess water than from drought, they are more likely to drown than die of thirst.  In dry regions occasional watering will be necessary during summer drought to maintain flowering, otherwise they’ll make do with natural rainfall.  Although a certain amount of humus is advised, excessive organic matter is to be strongly avoided.  There is no need to add ferlilizer. 
 
Many varieties make wonderful pot plants which makes it easier to put them into a frost-free place for the winter.  However, hardiness is always relative and in some areas it is possible to keep them in the garden all year.  In this case cut the plant down to 12 cm (5 inches) in the autumn and protect with a thick mulch of dead leaves and cover with fleece through the winter.
 
Non-hardy, autumn and winter flowering salvia :
 
These varieties need to be container-grown and are mostly from America.  They can also be planted in the spring (after all risk of frost is past) and then carefully dug up and re-potted in the autumn.  They generally prefer full sun to part shade and a spot sheltered from the wind.  Soil needs to be well drained, stagnant humidity is one of their worst enemies.  Most varieties will suffer more from excess water than from drought, they are more likely to drown than die of thirst.  In dry regions occasional watering will be necessary during summer drought to maintain flowering, otherwise they’ll make do with natural rainfall.  They prefer more feeding than the hardy salvia but whilst a certain amount of humus is advisable, excessive organic matter is to be strongly avoided.  If container-grown they will need feeding.   Prune back by a half after flowering.
 
Annual salvia :
 
This group includes the true annuals as well as those grown as annuals since they are so easy to grow from seed (sow in early spring, plant out in late spring, admire them all summer and into the autumn and then pull them out once the first frosts have killed them off).
 
The general growing conditions for salvia are appropriate for this group ; full sun, a well-drained soil, light watering and little or no feeding or additional organic matter (particularly for certain species from north Africa and California).
 
Certain species self-seed freely however, if you want to be sure of keeping them it is always best to collect some seed in order to sow again the following spring.