South Sea myrtle, Leptospermum scoparium, Manuka – care information

A South Sea myrtle is very picky about its location. In any case, the optimal place should guarantee one thing: lots of light in every season. This is not a problem in summer in our latitudes, because the plant can be placed outside from the end of spring. In winter it becomes more difficult to find a suitable place for the light-hungry Manuka.

• Light requirement: very high (all year round)
• nevertheless do not expose to the midday sun (south side).
• well ventilated
• Soil: airy, permeable to water and rich in humus
• lime-free (pH value 5 to 6)

watering and fertilizing

During the growing season, the Manuka should be watered plentifully. Constant moisture is important. The bush reacts very sensitively to waterlogging and drought (even for a short time). If the soil is too wet or too dry, the South Sea myrtle turns brown. She recovers only with great difficulty – or not at all – and dies completely. For this reason, the South Sea myrtle should not necessarily be placed on a south-facing window or a south-facing house wall without shade. In strong sunlight there is a risk that the root ball will dry out. With a cool hibernation, watering is less frequent, but even now the soil must not dry out. Low-lime water (rainwater or decalcified water) that is not too cold (room temperature) is suitable for irrigation.

In spring and summer, the southern sea myrtle responds to a 14-day fertilizer application with good growth. Conventional flower fertilizer can be used for this, which is administered via the irrigation water. However, only half the concentration recommended on the packaging should be used.

To cut

By nature, Leptospermum scoparium sometimes grows sparsely. Older, relatively unbranched shoots therefore overhang a little. The South Sea myrtle is very tolerant of pruning, so it is possible to cut it at regular intervals without any problems. A pruning is always necessary when the New Zealand myrtle is bare from the inside out or only has a few flowers. With the shortening of the shoots, the South Sea myrtle experiences a significant rejuvenation. It not only branches better, but also becomes more willing to flower again. It is advisable to cut young plants several times from the start in order to achieve good branching.

Preservation and thinning cut

If you cut your Manuka regularly, you only have to cut off dead or diseased shoots, twigs growing inwards and crossing branches. Longer, unbranched shoots are shortened by about a third each year. The time for pruning determines the flowering time of the manuka: shrubs such as New Zealand myrtle are pruned immediately after flowering.

• Time: young plants in spring (on a frost-free day)
• older plants after flowering
• Cut off long, unbranched branches after the third to fourth leaf base (eye).
• always cut over an outward facing eye
• remove all dried shoots
• Shorten diseased branches down to healthy wood
• Cut perennial, already bare branches down to ground level
• Completely remove inward-facing shoots
• if two branches cross, one of them is removed

taper cut

If the South Sea myrtle is getting old and has rarely been cut, it can become bare from below and from the inside. In addition, it becomes more sparse with age and produces fewer flowers. In this case, a makeover is called for. Although the manuka can be cut radically to about 20 cm above ground level, it then takes a few years to recover. A better method is therefore to proceed gradually and only severely shorten part of the branches at a time. So there are still enough shoots and flowers left to give the bush a visually appealing appearance. Such a radical measure is best done in winter, as the plant does not tolerate rigorous pruning during the growth phase.

1. Year: Cut about a third of all shoots to just before the first branch or 20 to 30 cm above ground level. Always cut over an outward-facing eye. The cut surface should be as smooth and small as possible. Distribute cuts evenly over the entire plant.
2. Year: Now the second third of the branches are shortened. Again, care must be taken to ensure that the cut shoots are evenly distributed over the entire plant. Only cut branches that were not shortened in the previous year.
3. Year: The last third – i.e. all shoots that have not already been shortened in the two previous years – still have to be cut.
4. Year: Now the South Sea Myrtle is fully rejuvenated. From the 4th year there is only one maintenance cut.

standard

New Zealand myrtles are sometimes also available as high stems in specialist shops. Anyone who owns such a rare specimen should pay a lot of attention to it. As a rule, all high stems are composed of two different plants. The basis is a strong, related plant, onto which the actual plant was grafted. In this case, the crown consists of South Sea myrtle. If you remove the shoots up to the grafting point or if you shorten them too much, the grafted plant will no longer be able to survive. It is also important that the base plant (root and trunk) grows significantly more than the crown. Therefore, all shoots that grow on the trunk or below the grafting point must always be cut close to the trunk at an early stage. Otherwise, it robs the grafted South Sea myrtle of its strength and livelihood. In the worst case, the refined crown is then simply rejected.

propagation

New Zealand myrtle can be propagated from seed or cuttings. Propagation from cuttings offers a significant time advantage over seed, making this method a better alternative for most gardeners. Successful propagation from cuttings requires cleanliness, moisture, warmth and of course a healthy mother plant. With the annual pruning of the South Sea myrtle, there are always a few shoots that are wonderfully suitable for the propagation of cuttings.

• When: March to early summer
• Cut off healthy, strong shoot tips
• Length: 10 to 15 cm
• use clean (sterile) cutting tools
• make sure the interface is smooth and clean
• Scrape or carve the bark at the lower end about two centimeters
• leave about three eyes (or leaf bases).
• Cut off the tip of the shoot
• remove about a third of the leaves (protection against high evaporation)
• Put three centimeters deep in moist potting soil
• Place the pot in a greenhouse
• alternatively put a freezer bag over the pot
• Set up without direct sunlight, but very bright
• air occasionally
• Temperature: 15 to 20 degrees

It has been shown that cuttings that take a long time to develop roots often develop mold on the substrate. To prevent this, the cutting can be placed in a normal household sponge or rock wool instead of in the substrate. To do this, place a piece of the material in a bowl of water and scratch or drill a small hole at the top into which the cutting is placed. Just enough water is then poured into the saucer so that about 1 cm of water remains in the bowl. If the cutting begins to grow, this is a sign that roots have formed. The young South Sea myrtle can now be planted in a pot with humus-rich substrate.

repot

South Sea myrtle grows very slowly, so it is sufficient to repot it into a slightly larger pot every two years in spring. Since the nutrient content in the old soil is only low and the pH value in the soil increases when watering with calcareous water, as much old substrate as possible should be replaced with fresh one when repotting.

• Time: spring
• Substrate: well-drained universal soil containing humus
• possibly some mature compost

hibernate

Leptospermum scoparium is not hardy. Although the plant tolerates short-term drops in temperature to just below zero degrees, permanent frosts cause it to die off quickly. For this reason, the South Sea myrtle should be placed in its winter quarters before the first frosts in October. A cool conservatory or a frost-free greenhouse is ideal. All other places where the temperatures are between five and eight degrees and where it is very bright also offer the South Sea myrtle good conditions for wintering. The lower the temperatures, the less you have to water. However, the bale must never dry out completely. During the hibernation is not fertilized.

• Temperature: 5 to 8 degrees
• very bright location
• alternatively work with plant lights
• ensure good air circulation (but no draughts)

diseases and pests

The New Zealand myrtle reacts very sensitively to care errors. Insufficient amounts of light in winter cause the leaves to wilt and fall off. In this case, a plant light or a much brighter location is essential for survival. Even short-term drought leads to brown discolouration, which usually results in the death of the plant. In the case of waterlogging, on the other hand, the roots rot. Only very rarely do pests visit the flowering bushes. If sucking pests such as spider mites still occur, it is because the plant is severely weakened. It is therefore not only necessary to combat the pests, but above all to check the care and site conditions.

Conclusion
The South Sea myrtle is one of the moderately easy-care potted plants. The most important criterion for their care is the constant water supply. While the plant tolerates extreme heat well, it is not at all tolerant of drought or waterlogging. The second condition for successful cultivation is that the Manuka is very bright in both summer and winter. Especially in winter, this condition poses a great challenge for many hobby gardeners.