Prostanthera (Lamiaceae)
Prostanthera is a genus of flowering plants; there are about 90 known species, all of which are endemic to Australia. In the Netherlands, only the species Prostanthera cuneata is known, although there are also several other species that are highly frost-tolerant. All Prostanthera species are bushy shrubs that sometimes have very aromatic leaves.
Prostanthera cuneata is the best-known Prostanthera shrub in the Netherlands. It is usually available at Intra-Tuin or your local nursery.
It has very aromatic foliage, requires no protection from the winter cold in our climate, and blooms in June.
This plant has been in our garden since 2010 and is fully hardy.
In our garden, this Prostanthera is planted in bone-dry sandy soil, and I suspect it would do much better in soil that retains moisture well.
Prostanthera ‘Badja Peak’wasintroduced in England by Jeff Irons.
I've provided cuttings to the Rein and Mark Bulk nurseries and the Esveld nursery, so I'm sure it will be available for purchase there in the future.
In terms of hardiness, this Prostanthera is on the borderline. I protect it with a fleece cover, and it didn't suffer any damage at all during the winter of 2012–2013.
If you love rare plants, this is definitely a must-see. You won't find this in your neighbors' gardens anytime soon.
Prostanthera monticolaalso known as Buffalo Mint bush. I received this Prostanthera from Merrigum Nursery. I wasn’t very confident that it would survive the winter, but with just a little bit of fleece, it suffered no damage at all during the winter of 2012/2013.
Unfortunately, this plant died in the summer of 2014 because the trunk had split open
Care:
Prefers a location in full sun or partial shade, with acidic to neutral, humus-rich soil. Older plants benefit from light pruning in the spring.
Tolerates drought but does not do well in wet winter conditions.
According to the book ‘Australian plants and a guide to their cultivation in Europe,’ Prostanthera plants often die from Phytophthora cinnamomi infection—just so you know.
Cuttings:
In my opinion, this is a better way to propagate the plant than sowing seeds. Cuttings can root within 3–4 weeks.
Sowing:
Seeds should be stored at a temperature of 4°C; they germinate slowly and the process can sometimes take up to 9 months.
Hardy?
Prostanthera cuneata is highly frost-tolerant and generally does not need to be protected in winter.
Prostanthera ‘Badja Peak’ is on the verge of dying, so I’m protecting it (just to be safe) with burlap in the winter
Prostanthera monticola isn't very hardy here, so it does need protection in the winter.
Availability:
Prostanthera cuneata is available for purchase almost everywhere, for example at Bastin Nursery
Prostanthera ‘Badja Peak’is available for purchase fromRein and Mark BulkandEsveld
Prostanthera monticola is probably available for purchase somewhere in England.
Update:
There are hybrids with Prostanthera cuneata and Prostanthera lasianthos or Prostanthera phylicifolia that are quite hardy, perhaps even fully hardy.