Article by David Marks
Salvia nemorosa ‘Ostfriesland’ is a perennial which has a life expectancy of many years. They can be left to their own devices for six or seven years and may then benefit from being divided into two or more individual plants which will then live for many more years after that.

This variety of Salvia has won the RHS Award of Garden Merit. A large number of expert garden designers include it in their most popular garden plants list because of its flowering capabilities and ease of maintenance.

Use the checklist below to decide if Salvia nemorosa ‘Ostfriesland’ is suited to your preferences and garden conditions:

• They grow to roughly 40cm / 16 inches high, and will spread to around 40cm / 16 inches in three years but the centre of the plant remains very compact.
• Masses of violet blue flowers appear starting in July. The stems are an attractive dark pink. Flowers are produced until mid September.
• The leaves are a mid-green colour and have a very pleasant scent. These die down in October / November time.
• The best soil for growing Salvia nemorosa ‘Ostfriesland’ is a light well draining one such as loam, chalk or sand. They do not do well on clay unless it has been improved with lots of organic matter to help drainage.
• They are best grown in full sun conditions. The best flower colour occurs in a sunny position. Salvia nemorosa ‘Ostfriesland’ needs a moist soil
• The only maintenance required is a handful or two of fish, blood and bone fertiliser in spring. Dead heading the flowers, if you have time, will extend the flowering period.
• They are low maintenance if the soil is kept moist.
• No parts of the plant are poisonous to humans.
• They make good cut flowers.
• They can successfully be grown in containers.
• They are fully hardy in all parts of the UK down to -22°C / -11°F.

WHERE TO BUY SALVIA NEMOROSA OSTFRIESLAND

Many garden centres will sell Salvia nemorosa ‘Ostfriesland’ so there is no difficulty in obtaining them. They are also widely available online.

Our recommendation for a reputable online supplier with a five year guarantee would be Crocus. They have served us well and supply healthy, good sized plants which are  extremely well packaged. Click here for their page on Salvia nemorosa ‘Ostfriesland’ to buy online from our recommended supplier.

 

HOW AND WHEN TO PLANT SALVIA NEMOROSA OSTFRIESLAND

Planting from pots is the most reliable method as described below

• Choose a sunny to partial shade position. Somewhere where the soil is normally moist but not waterlogged.
• If the soil is heavy or is not free draining add lots of well rotted compost to the area and dig it in well.
• It can be planted all year long if the soil is not frozen and you can water well when conditions are dry. Mid March to April and mid September to October are the best times to plant potted salvias.
• Dig a hole twice the width of the rootball. Sprinkle in a handful of blood, fish and bone and work into the ground.
• Place the plant into the hole, filling in with soil so that it is at the same depth as was in the pot. Fill around the rootball and firm the soil down gently but firmly. Water well to settle the surrounding ground around the rootball.

HOW TO CARE FOR SALVIA NEMOROSA OSTFRIESLAND

Salvia nemorosa ‘Ostfriesland’ are low maintenance plants and need very little care other than keeping the area around them weed free.

Although these plants withstand drought well when they are established a mulch of organic matter around them in spring will conserve water and supply a low level supply of nutrients throughout the year. A mulch is especially important when newly planted and the root system is not fully developed.

In spring when your salvia starts showing signs of growth it’s best to prune back last year’s stems and any dead flowers to new growth. As an easy guide, you can trim the plant down to 25cm / 10in high.

You can also extend the flowering period by dead heading the flower spikes as they die.

HOW TO DIVIDE SALVIA NEMOROSA OSTFRIESLAND

If, after five years or so, the number of flowers produced starts to decline, then it may be time to divide your Salvia nemorosa ‘Ostfriesland’. The best time to do this is in Spring, April is normally about right.

Before dividing it, make sure the plant is well watered the day before. Trim off all the foliage and flowers (if any) to about 15cm / 6in from the rootball. Because these plants spread very easily you may well be surprised to find out just how small the rootball is.

Dig up the rootball with a fork keeping as many of the roots attached as possible. Then it’s simply a matter of cutting the rootball into two or three equal parts. This can be done by prising it apart with your hands or literally cutting it with something like a hacksaw.

Replant each of the parts in their new positions to the same depth as the original plant and water in well. Don’t feed until the plant has developed new leaves.

GROWING SALVIA NEMOROSA OSTFRIESLAND IN CONTAINERS

Salvia nemorosa ‘Ostfriesland’ plants are ideal for growing in containers. They flower for longer than many other plants and shrubs.

Because of their preference for a well drained but moist soil they will need to be watered regularly and good drainage holes in the pot or container are a must.

A 45cm / 18in wide container is about the smallest advisable. The larger the container the happier the plant will be, it will require watering less frequently. A container 30cm / 12 in deep is fine but again, the deeper it is the less frequently it will need watering.

Feed your plant in spring and autumn with a good handful of fish blood and bone. It will also be beneficial to feed it once a month with a liquid plant food such as Miracle Gro or similar. Salvia nemorosa is fully hardy in the UK so frost will not be a problem even when grown in a container.

One nice container planting idea we have seen is to under plant with snow drops or daffodils. By the time your salvia wakes up from its winter rest the daffodils or snow drops will have died down.

PESTS AND DISEASES OF SALVIA NEMOROSA OSTFRIESLAND

Salvia nemorosa ‘Ostfriesland’ is very strong growing and in normal conditions is a pest and disease free. The few problems you might encounter are listed below.

VINE WEEVIL

This may be a problem with plants grown in containers but Salvia nemorosa is no more susceptible than other plants. See our page here for diagnosing and treating vine weevil.

MILDEW

Occasionally hardy salvias can suffer from mildew, see our page here for diagnosing and treating this problem.

SALVIA NEMOROSA OSTFRIESLAND SUMMARY

Below we list the key strengths and weaknesses of Salvia nemorosa ‘Ostfriesland’.

HARDY	(to -22°C / -11°F)
CLAY SOIL	Not without improvement
SANDY SOIL	Yes
DRY SOIL	Yes when established
SHADE	No
EVERGREEN	No
EASY CARE
SMALL GARDENS	Yes
POT / CONTAINER	Yes
FLOWERING
FLOWER TIME	July to September