Making your own alpine/rock garden trough

With today's suburban spread, infill housing and apartment living, areas for growing native plants can sometimes be limited.

Hebe grows well in plant boxes.

Hebe grows well in plant boxes.

However you can still grow our native treasures even where space is tight. The plants of our mountains and many of the coast are small in stature due to the harsh environments they have evolved in.

These plants might get "lost" in a large garden but putting them together in a miniature trough garden allows them be easily seen, enjoyed and cared for.

A trough garden can be situated on patios, decks and even rooftops.

Mountain daisies (Celmisia), Heliohebes, buttercups (Ranunculus) forget-me-nots (Myosotis), speargrass, tussocks (Rytidosperma, Festuca, Carex), whipcord hebes (Hebe), mountain carrots (Anisotome), and Raoulia can all be interesting plants for a trough.

 

Materials:

2 strong cardboard cartons, one 5 cm smaller on all sides
2 or 3 drainage plugs - corks will do
heavy blocks or bricks
2 parts (by volume) finely granulated pine bark
1 part (by volume) cement
1 part (by volume) coarse sand

Construction:

Place blocks around larger carton on firm, flat base
Dry mix fine granulated bark, sand and cement
Mix to 'dough' consistency with water
Place at least 5 cm layer of mix in carton base
Set drainage plugs in mix
Fill in sides (between cartons) with mix
Firm down well, leave overnight
Next day remove blocks and carton walls carefully
Brush down gently with brush to simulate hewn stone
Carefully take out plugs
Do not move or plant for at least 3-4 days

Soil mix: Generally plants from higher altitudes don't like earth that is too rich or wet. Gluggy earth will cause rot, earth too rich will burn their fragile root system.

It is easy to ensure neither of these things happen if you follow the growing mix recipe below:
thoroughly mix:
1 part clay
1 part well rotted compost and
1 part grit or sand
and fill your planter or trough with this mix.

Set in some interesting small stones to simulate a miniture rocky landscape. Plant straight into the mix with no fertilizer. Position plants slightly higher than the level of the mix and cover the entire surface with about 2 cm of pea metal. This will prevent
collar-rot and keep weeds at bay for a long time.

Water in well.

After initial watering, water only as necessary in hot, dry weather. Topdress annually with grit and a pinch (and I do mean a pinch) of blood and bone.

The same soil mix is appropriate for making larger rock gardens without troughs.

Thank you to Muriel Fisher for permission to use the above information from Growing New Zealand Plants, Shrubs, and Trees (Bateman)

You may need to go to a specialist native plant nursery to find some of the more unusual plants. Or alternatively order them via the internet or inquire after a nursery's catalogue.