The Complete Plant Guide for Otago & Southland Gardens

Climate Zone 5-6: Cold Temperate to Sub-Alpine

Otago and Southland represent New Zealand's most challenging gardening conditions, from Dunedin's coastal climate to Central Otago's extreme continental conditions and Southland's short growing seasons. Success here requires careful plant selection, precise timing, and realistic expectations while embracing the unique beauty of cold-climate gardening.

Understanding Your Southern Climate

Key Characteristics:

• Very cold winters with severe frosts (-10 to -15°C)

• Short, intense summers (20-25°C maximum)

• Low annual rainfall (300-600mm) except western areas

• Extreme temperature variations between seasons

• Strong winds year-round, especially westerlies

• Excellent winter chill for temperate fruits

• Very short growing season (4-6 months)

Unique Challenges:

• Killing frosts possible 8-9 months of the year

• Short season demands precise timing

• Strong winds require substantial permanent shelter

• Drought conditions in Central Otago rain shadow areas

• Hail and snow damage can devastate plantings

• Limited plant palette compared to warmer regions

Native Plants for Extreme Southern Conditions

Alpine and Sub-Alpine Trees

Mountain Beech (Nothofagus solandri var. cliffortioides)

• Deciduous native suited to cold conditions

• Beautiful golden autumn color

• Slow-growing but extremely hardy

• Good for cooler, moister sites

Silver Beech (Nothofagus menziesii)

• Evergreen beech for milder sites

• Attractive silvery bark

• Slow establishment but very long-lived

• Better for areas with some shelter

Mountain Totara (Podocarpus nivalis)

• Low-growing alpine conifer

• Extremely hardy in harsh conditions

• Good for rock gardens and exposed sites

• Red berries attract native birds

Dracophyllum (Grass Tree species)

• Distinctive architectural form

• Various sizes from shrubs to small trees

• Very hardy in harsh alpine conditions

• Unusual texture and growth habit

Hardy Native Shrubs

Matagouri (Discaria toumatou)

• Extremely hardy spiny shrub

• Outstanding windbreak and barrier plant

• White flowers attract beneficial insects

• Tolerates extreme cold and drought

Coprosma species

• Various hardy species suited to cold conditions

• C. propinqua excellent for harsh sites

• Berries provide food for native birds

• Good informal hedging plants

Hebe species

• Many hardy species for southern conditions

• H. odora and H. pinguifolia very hardy

• Compact forms suit harsh conditions

• Flowers attract beneficial insects

Olearia species (Daisy Trees)

• Several species tolerate harsh conditions

• O. nummulariifolia very hardy and compact

• White flowers attract beneficial insects

• Good for informal shelter plantings

Groundcovers and Alpine Plants

Snow Tussock (Chionochloa species)

• Native tussock grasses extremely hardy

• Important for soil stability and wildlife

• Attractive seed heads add winter interest

• Various species for different elevations

Raoulia species (Vegetable Sheep)

• Cushion plants native to high country

• Extremely hardy in harsh exposed conditions

• Interesting form and texture

• Good for rock gardens and alpine areas

Celmisia species (Mountain Daisies)

• Large white daisy flowers

• Silver foliage attractive year-round

• Very hardy alpine perennials

• Good for mass planting in harsh conditions

Acaena species (Biddy-biddy)

• Low-growing groundcover plants

• Attractive foliage and interesting seed heads

• Very hardy in poor conditions

• Good for covering difficult areas

Exotic Plants for Southern Conditions

Ultra-Hardy Trees

Betula species (Birches)

• Excellent cold tolerance and attractive bark

• Good autumn color before leaf drop

• Fast-growing for quick results

• Various species suit different conditions

Populus species (Poplars)

• Extremely fast-growing windbreak trees

• Lombardy poplars good for narrow spaces

• Provide quick shelter for other plants

• Some varieties have attractive autumn color

Salix species (Willows)

• Very fast establishment for shelter

• Good for wet areas and stream banks

• Early catkins provide nectar for bees

• Various sizes from shrubs to large trees

Larix species (Larches)

• Deciduous conifers with excellent cold tolerance

• Beautiful golden autumn color

• Good specimen trees for larger properties

• Slow-growing but very hardy

Fruit Trees (Excellent Winter Chill)

Stone Fruits

• Apricots exceptional in Central Otago conditions

• Cherries excellent with adequate shelter

• Plums including European varieties very successful

• Choose varieties with appropriate chill requirements

Pip Fruits

• Apples outstanding with proper variety selection

• Pears including cold-hardy European varieties

• Choose varieties suited to very short seasons

• Pollination planning critical for reliable crops

Berry Fruits

• Blackcurrants and redcurrants very hardy

• Gooseberries excellent in cool conditions

• Raspberries productive with shelter

• Strawberries possible with protection

Unusual Cold-Hardy Fruits

• Sea buckthorn extremely hardy and productive

• Honeyberries (Haskap) excellent cold tolerance

• Chokeberries very hardy with health benefits

• Elderberries hardy and productive

Ornamental Shrubs

Spiraea species

• Very hardy flowering shrubs

• Various species for different purposes

• Spring or summer flowering varieties

• Good for informal hedging

Potentilla fruticosa (Shrubby Cinquefoil)

• Extremely hardy low shrub

• Long flowering period

• Various flower colors available

• Good for difficult sites

Rosa rugosa (Japanese Rose)

• Outstanding cold tolerance

• Fragrant flowers and decorative hips

• Good barrier plant with thorns

• Self-sufficient once established

Ribes species (Currants)

• Flowering currants very hardy and attractive

• Spring flowers often fragrant

• Some species have edible fruit

• Good for wildlife and beneficial insects

Protected Growing and Season Extension

Greenhouse Gardening

Essential for Vegetable Production:

• Unheated greenhouses extend season significantly

• Heated houses allow year-round production

• Choose varieties suited to greenhouse growing

• Proper ventilation prevents disease problems

Suitable Greenhouse Crops:

• Tomatoes with appropriate varieties

• Peppers and eggplant with heat

• Lettuce and greens year-round

• Herbs for fresh winter harvesting

Cold Frame Utilization

Season Extension Tool:

• Valuable for starting plants early

• Hardening off greenhouse-grown plants

• Growing winter crops with protection

• Seed starting in spring

Appropriate Cold Frame Crops:

• Hardy lettuce and Asian greens

• Spinach and winter herbs

• Starting summer crop seedlings

• Root vegetables with protection

Polytunnel Benefits

More Affordable Protection:

• Significant season extension

• Protection from wind damage

• Warmer soil for root development

• Shelter for establishing young plants

Regional Climate Variations

Coastal Otago (Dunedin Area)

Characteristics:

• Moderate temperatures with sea influence

• More reliable rainfall than inland areas

• Salt spray affects coastal gardens

• Less extreme temperature variations

Advantages:

• Longer growing season than inland

• Less severe frosts

• More reliable moisture

• Wider plant palette possible

Central Otago

Characteristics:

• Extreme continental climate

• Very hot summers, very cold winters

• Very low rainfall (300-400mm annually)

• Extreme day/night temperature variations

Management Requirements:

• Irrigation absolutely essential

• Shelter critical for plant survival

• Very precise timing required

• Limited to extremely hardy plants

Vegetable Gardening in Extreme Conditions

Maximizing the Ultra-Short Season

Critical Timing (November-March Only):

• Start all plants indoors or in greenhouse

• Transplant only after all frost risk passes

• Choose shortest-season varieties available

• Focus on quick-maturing crops

Essential Season Extension:

• Heated greenhouse for reliable production

• Cold frames for hardening off plants

• Row covers for frost protection

• Succession planting in protected conditions

Hardy Vegetable Varieties

Root Vegetables:

• Carrots: choose short-season varieties

• Parsnips: very hardy, can overwinter

• Beetroot: quick-growing varieties

• Turnips and swedes: excellent cold tolerance

Brassicas:

• Kale: extremely hardy, can overwinter

• Brussels sprouts: excellent cold tolerance

• Cabbage: choose quick-maturing varieties

• Broccoli: fast varieties with protection

Quick Crops:

• Radishes: 30-day varieties

• Lettuce: cold-hardy varieties

• Asian greens: fast-growing, cold-tolerant

• Herbs: focus on very hardy types

Container and Indoor Growing

Year-Round Production:

• Herbs in pots brought indoors

• Microgreens and sprouts

• Windowsill growing

• Heated greenhouse production

Mobile Gardening:

• Large containers moved to protection

• Greenhouse benches for portability

• Cold frames with removable tops

• Portable growing systems

Garden Design for Survival Conditions

Absolute Shelter Priority

Essential Windbreaks:

• Multiple barrier layers required

• Artificial windbreaks may be necessary initially

• Plant shelter in most protected areas first

• Allow years for windbreaks to become effective

Effective Shelter Plants:

• Cupressus macrocarpa: very hardy and dense

• Pinus sylvestris: excellent cold tolerance

• Poplar species: extremely fast establishment

• Mixed native plantings for long-term value

Microclimate Creation

Every Degree Matters:

• North-facing slopes warmest

• Shelter from buildings and structures

• Thermal mass from stones and concrete

• Protected courtyard areas

Heat Accumulation:

• Dark surfaces absorb and radiate heat

• Water features provide thermal mass

• South-facing walls reflect heat

• Enclosed areas trap warm air

Frost Management

Understanding Frost Patterns:

• Cold air flows downhill and pools

• Avoid planting in frost hollows

• Elevated positions often warmer

• Buildings and structures affect air movement

Protection Strategies:

• Physical covers for valuable plants

• Mulching to insulate soil

• Proper timing of pruning and feeding

• Choose naturally hardy varieties

Recommended Plant Lists by Hardiness

Ultra-Hardy (Zone 5 and below)

Trees:

• Betula species (birches)

• Populus species (poplars)

• Salix species (willows)

• Larix species (larches)

• Native beech species

Shrubs:

• Rosa rugosa

• Spiraea species

• Potentilla fruticosa

• Ribes species

• Hardy hebe varieties

Perennials:

• Iris sibirica

• Hemerocallis (daylilies)

• Sedum species

• Native alpine plants

• Hardy ornamental grasses

Moderately Hardy (Zone 6)

Trees:

• Some maple species

• Hardy oak varieties

• Mountain ash (Sorbus)

• Native totara species

• Some pine species

Shrubs:

• Hardy rhododendrons

• Viburnum species

• Weigela varieties

• Hardy fuchsia species

• Berberis species

Perennials:

• Peonies

• Hardy geraniums

• Astilbe species

• Hosta in sheltered positions

• Hardy lavender varieties

Requires Protection (Zone 7+)

Plants Needing Greenhouse or Extreme Shelter:

• Citrus (greenhouse only)

• Most Mediterranean herbs

• Tender perennials

• Non-hardy annuals

• Tropical houseplants (indoor only)

Seasonal Calendar for Southern Gardening

Spring (October - December)

October:

• Soil preparation when ground thaws

• Start seeds indoors or in heated greenhouse

• Plan garden layout and improvements

• Check and repair winter damage

November:

• Begin transplanting hardy varieties outdoors

• Continue indoor seed starting

• Prepare planting areas

• Install season extension equipment

December:

• Main outdoor planting period begins

• Transplant greenhouse-grown seedlings

• Direct sow quick-maturing crops

• Establish irrigation systems

Summer (January - February)

January:

• Peak growing period with intensive management

• Monitor frost risk even in summer

• Continue successive plantings

• Harvest early crops

February:

• Begin autumn preparations

• Harvest and preserve intensively

• Plant any remaining quick crops

• Begin protecting tender plants

Autumn (March - April)

March:

• Major harvest period

• Begin winter preparations

• Plant garlic and overwintering crops

• Start planning next year's garden

April:

• Final harvest before hard frosts

• Complete winter protection installation

• Begin major cleanup

• Plan greenhouse winter growing

Winter (May - September)

May-September:

• Outdoor gardening essentially stops

• Focus on greenhouse/indoor growing

• Planning and preparation time

• Tool maintenance and repair

• Order seeds and plan next season

Problem-Solving Extreme Weather

Frost Damage Recovery

Assessment:

• Determine extent of damage after frost events

• Wait before removing apparently dead plants

• Some plants recover from roots even if tops are killed

• Learn from damage patterns for future protection

Prevention:

• Choose appropriate planting times

• Use physical protection for valuable plants

• Understand your local frost patterns

• Plant hardy varieties as your foundation

Hail Damage Management

Protection:

• Hail nets over valuable crops

• Temporary covers during hail warnings

• Choose varieties with thicker leaves

• Plan garden layout to minimize exposure

Recovery:

• Remove damaged plant material promptly

• Assess and treat wounds to prevent disease

• Replant damaged areas if season allows

• Learn from patterns for future planning

Snow Load Management

Prevention:

• Choose plants with flexible branches

• Avoid broad-leafed evergreens in snow areas

• Prune to reduce snow-catching surfaces

• Support valuable plants with stakes

Response:

• Remove snow gently from evergreen branches

• Allow deciduous plants to drop snow naturally

• Assess damage after snow melts

• Plan structural improvements for next winter

Local Resources and Community

Southern Gardening Networks

Knowledge Sharing:

• Local gardening clubs with extreme-climate experience

• Online forums specific to southern New Zealand

• Seed swapping groups for hardy varieties

• University extension services

Educational Opportunities:

• Botanic gardens in Dunedin and Invercargill

• Agricultural field days and demonstrations

• Master gardener programs

• Local nursery workshops

Specialized Suppliers

Hardy Plant Sources:

• Nurseries specializing in cold-climate plants

• Mail-order suppliers of hardy varieties

• Seed companies with appropriate varieties

• Specialty fruit tree suppliers

Equipment and Infrastructure:

• Greenhouse suppliers and installers

• Irrigation system specialists

• Frost protection equipment suppliers

• Season extension equipment

Success Strategies for Southern Gardens

Realistic Expectations

Embrace the Challenge:

• Focus on plants that thrive rather than struggle

• Appreciate the unique beauty of hardy plants

• Value the intense but brief growing season

• Celebrate successes rather than lamenting limitations

Long-Term Planning:

• Invest in permanent infrastructure first

• Choose long-lived, hardy plants as foundation

• Plan for gradual garden development

• Build resilience into every garden decision

Making the Most of Conditions

Seasonal Intensity:

• Make every day of the growing season count

• Preserve and store intensively during harvest

• Appreciate the dramatic seasonal changes

• Use winter for planning and preparation

Hardy Beauty:

• Native alpine plants offer unique beauty

• Deciduous plants provide stunning autumn displays

• Winter structure becomes critically important

• Spring emergence is dramatically appreciated

Building Garden Resilience

Infrastructure Investment:

• Greenhouses and cold frames essential

• Windbreaks are long-term investments

• Quality tools built for harsh conditions

• Irrigation systems for reliable water supply

Plant Selection Philosophy:

• Choose plants that will thrive, not merely survive

• Native plants often outperform exotics

• Hardy varieties more rewarding than marginal ones

• Focus on proven performers rather than experiments

Embracing Southern New Zealand's Garden Character

Gardening in Otago and Southland requires a different mindset from warmer regions. Success comes from working with the climate rather than fighting against it, and from appreciating the unique beauty that extreme conditions create.

The short but intense growing season creates gardens with dramatic seasonal contrasts. Plants that survive here develop exceptional character and resilience. The brief spring emergence, intense summer growth, spectacular autumn colors, and stark winter beauty create a garden experience unlike anywhere else in New Zealand.

Focus on building garden infrastructure and choosing plants that will thrive in these challenging conditions. Embrace protected growing as an essential tool rather than a compromise. Value the unique plants that flourish in cold conditions - from hardy natives to ultra-hardy exotics that simply won't grow in warmer regions.

Your southern garden becomes a testament to resilience, careful planning, and the unique beauty that emerges from challenging conditions. Every successful harvest, every plant that survives a harsh winter, every spring emergence becomes a celebration of the gardener's skill and nature's remarkable adaptability.

With realistic expectations, appropriate infrastructure, and plants chosen for local conditions, southern New Zealand gardens can be extraordinarily rewarding, providing beauty, produce, and deep satisfaction from succeeding in one of the world's most challenging gardening climates.