Plant Profile
Myosotidium hortensia (Chatham Island Forget-Me-Not) is a stunning New Zealand native producing deep green, glossy foliage and a profusion of deep blue flowers in spring. It prefers a shaded site with moist, free-draining soil, and slightly acidic. They are evergreen, but there will be some die-back in winter on exposed sites.
 
Myosotidium hortensia are mainly used for landscaping in residential properties, but are a great gap filler in protected areas of schools, parks etc. They're also very useful plants because they grow quickly and don't need much care. Try placing them in a south-facing inside corner of your house, or behind a formal box hedge to create interest.
 
The name ‘forget me not’ comes from the fact this plant doesn’t forget to flower every year – it does seem to forget to produce seeds though! This hardy perennial will survive under 5cm of water in summer. Not suitable for dry areas.
 
Since 2012, the conservation status of Chatham Island Forget-Me-Not has been listed as Threatened – Nationally Vulnerable, and unfortunately the only white flowering type in the wild has been destroyed by coastal development, which is a great reason to plant the "alba" variety.
The fleshy leaves are easily distinguished from other plants, and in fact it is the single species in a genus of plants belonging to Boraginaceae family so it is hard to mistake the large and beautiful green leaves of this endemic plant.
 
Care
You’ll want to give them plenty of water while they are first establishing themselves, however once they’re underway they are pretty tough. Sometimes the existing largest leaves will die off but you should notice new shoots appearing from the centre which will replace these older leaves. As a regular maintenance task, you should prune off spent flower heads and old leaves annually to keep the plant looking fresh. This can be done late autumn/winter.

Location
It is endemic to the group of Chatham Islands, including Chatham Island (Rekohu), Pitt Island, South East, Mangere and most of the smaller islands, islets and some rock stacks. For this reason, it is suitable for growing in coastal locations, even coastal cliffs. However wind is not ideal, so a sheltered spot is best and ideally partial shade. It has large, stout roots that grow in a fairly shallow system, which means they can tolerate a range of soils and even full sun as long as the roots are kept cool. In the shade of larger trees is good for partial shade, however don’t place them too close as the roots will be competing for water. Best protected from frosts when young, but generally hardy once mature.

Watering
Myosotidium hortensia likes water, as long as it can drain away. When it is young it needs frequent watering. Once mature it should be able to handle nature’s course, except if they are planted in pots – then you will need to continue to keep them watered regularly. It is amazing how quickly plants can dry out in containers!

Feeding
They will respond well to mulching in spring, and a regular feed of liquid seaweed. However, if the natural environment is right for them, and the leaves are lush and vibrant green, there is no need to over-feed it.

Overwintering
If you live in a frost-prone area, it would be well worthwhile rigging up a frost cloth frame to roll on during winter. These can be simply constructed using fibreglass rods from a garden centre, inserted into the ground or a tube, and bent over to form a hoop. Frost cloth can then be pulled over and held in place with clips, rocks, or soil.

Pruning
Chatham Island Forget-Me-Nots are very easy care, all that is required each year is to trim off spent flower heads and any dead leaves. You may want to thin out a couple of leaves here and there if they are growing close to a house/building and they look a bit cluttered.

Propagation
Propagation is usually carried out by collecting ripe seed in autumn, and sowing immediately while they are still fresh. However, they don’t seed every year so sometimes seed can be a bit scarce! If you miss this opportunity in autumn, you can lift plants in early spring and divide them by hand.
The seed normally has a hard protective coating, and nicking this with a sharp blade at the radicle end (usually the scarred end where it was attached to the plant) will improve germination.

Diseases
Generally these plants are disease free, any discolouration of the leaves is likely to be from lack of water or nutrition, or environmental damage (frost, windburn, sunburn etc). In humid climates they may attract fungal diseases, which can normally be treated with a fungicide available from garden centres. Interestingly, in 2007 a rare form of rust fungi was discovered on a single plant on the Chatham Islands, but to date this has never been seen anywhere else.

Insects/Pests
Because the leaves are fleshy, they are a great target for slugs and snails, so keep an eye out for this and apply slug bait around the plants when any holes appear in the leaves. This is readily available at garden centres.
 
Substitutes
Myosotidium hortensia are quite unique, so there are no close substitutes for it however other large leaf perennials can be used. A favourite of mine is Ligularia reniformis (Tractor seat plant), although the leaves don’t grow as large or thick.
 
Plants to pair with
Because of the large leaves, it is best planted with finer-leafed plants. For example a box hedge along a path with these planted in the space behind that and the wall of the house looks impressive. In a mixed garden, planting with other lovers of similar conditions works well, eg ferns and primulas. Also fit in well with hydrangeas.
 
Links
For great photos and further info visit https://www.citscihub.nz/Phil_Bendle_Collection:Myosotidium_hortensia_(Chatham_Islands_forget-me-not) 
Botanical info https://www.nzpcn.org.nz/flora/species/myosotidium-hortensia/