Weather is about the wind, rain, sunniness and temperature of a particular time. It is one of Kiwi's favourite topics of conversation, and even more so amongst gardeners! Our uneven terrain makes weather prediction difficult, but you can find weather forecasts at the Metservice for Hamilton and Tokoroa, or at the end of television or radio news broadcasts. 

Climate is the average weather for a particular place over a long time (eg 30 years).  NIWA is a government owned agency that tracks and predicts our climate - useful for planning planting. 

Plants from different parts of the world have developed in a particular climate.  When we bring them to the Waikato, their survival depends largely on how closely we can match their climate of origin. 

Another other key factor is soil, which feeds the plant. 

New Zealand has four seasons:

  • Spring - September, October, November
  • Summer - December, January, February
  • Autumn - March, April, May
  • Winter - June, July, August
In the Waikato our prevailing (most common) wind comes tends to come from the West. Southerly winds tend to be cold and like south-westerlies tend to bring showers and sometimes rain and thunder.  (Very occasionally we get tornadoes but they are generally small.)  Sometimes tropical depressions move down over New Zealand, particularly during December and April, bringing some of our worst storms.  They can bring heavy rain and wind. 

There is a reason that the Waikato is "where the grass is greener": we tend to get rain all year round, which why we have so much horticulture and dairying in this area.  More rain falls in winter than summer, with Hamilton's average rainfall about 1,200 mm per year. Our climate is also fairly humid which can make fungal diseases a problem. We are known for our fog.  Fog  forms over moist or marshy ground (such as drained peat swamps) on cloudless nights with light winds, so are particularly common in Autumn.  Climate change is expected to not only increase our average temperature, but generate more extreme weather events such as droughts and floods.

Here in the Southern Hemisphere, the warmest part of your garden faces North: it will get the most sunshine. Hamilton averages about 2013 hours of sunshine per year.  Most food plants do best with 6-8 hours of full sunshine per day.  In the tropics the daytime length (ie period when the sun is in the sky) is pretty constant, but here the day length varies considerably.  Our winter solstice (the longest night/the shortest day), falls on the 21 June, when the sun rises about 7:30 am and sets about 5:10 pm, while the summer solstice (longest day of the year) falls around December 22, with the sun rising about 6 am and setting about 8:40 pm.  The equinox (when the night and day length are the same), falls in March and September: this is often a period of windy unsettled weather that can damage plants if they are not sheltered.  Some gardeners believe that the shortening days after the summer solstice trigger many plants to go to seed (start forming seed).

The coldest months of the year are usually July and August and the hottest months in January and February.  In Hamilton, the average maximum temperature in January was 24 degrees compared with July's 13.6 degrees.  The average January minimum temperature is 12.7 degrees, compared with 3.8 degrees in July.  Temperatures have been recorded as low as -9.9 degrees and as high as 34.7 degrees.  Hamilton gets an average of 64 frosts at ground level per year. (Information from the Metservice)  Generally the worst of the frosts are over by Labour Weekend in October. 

A private weather station in Tokoroa keeps some historical temperature averages.  In the years 2008-2010 Tokoroa averaged 52 frosts per year.  The average January maximum temperature in this period was 30.7 degrees, compared with 15.3 in July.  The average January minimum temperature was just 4.3 degrees, compared with -6.0 degrees in July.  Only December - March were frost free.  


Tokoroa is at an altitude of 326 meters, much higher than Ruakura in Hamilton at just 40 meters, and further south.  These are factors in Tokoroa having colder temperatures.  Snow is extremely rare in Hamilton, but less so in Tokoroa. 


Hamilton has varied terrain and varied soil types with it.  There is a soil map here.  Click on the area where you plan to garden and click to see the soil type, for example gravelly sand, clay, silt loam and peat for example.  Each type has its benefits and downsides, suiting different types of plants.  Tokoroa has predominantly volcanic pumice soils over volcanic ash and are often low in the trace element cobalt. 


Within your garden there may be many micro-climates - areas that are more windy, cooler, or wetter than others. There can also be variations in soil type. The observant gardener matches plants to the different areas, and creates new micro-climates using techniques like cold frames or changes the soil with the use of 'soil amendments' such as compost.


If you have any questions, information or suggestions about weather, climate or soil, please add them to the discussion.

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Sit cloches over tender plants in the garden to protect from cold weather.

Or use to cover seeds sown in trays/pots until the seedlings are almost ready to be planted.

This cloche was made by Clare from a recycled airing rack and heavy plastic.

Can be folded when not in use. 

Note vent (hole in plastic) near top.

Get large pieces of recycled plastic sheeting for free from:

  • Furniture shops
  • Bed shops
  • People who have shifted house using commercial moving companies – the beds etc are often wrapped in plastic.

CREATING WARMTH - another cloche

Recycled window,  timber, hinges and handle. 

Set against a building for extra warmth.

Window can be propped open to control temperature and air flow.


You can sometimes get a free window when people are renovating - ask if you can have it when you see a window in a skip (big bin).  (That's how we got this one!)


NZ Gardener magazine have step-by-step instructions for building your own cold frame: download for free from their DIY page.


Saw this at the NZ Tree Crops Association Annual Tree Sale:


Glass/Perspex & wire. 


Can change how much the top opens to control temperature and air flow.


Folds flat when not in use. 


Frame $9

Frame + glass $15

from Joy in Hamilton, ph (07) 855 5931

Or try Trade Me, etc.

Bread Tray Cloche


Used for protecting young plants from wind, frosts, direct sun, some insects (eg white butterfly) and birds. 


The cloth versions can be used as the first stage of ‘hardening off’ (acclimatizing) young plants that have been raised in a green house or warm windowsill.



Base = bread tray

Wooden frame (could be recycled timber)

Removable cover =

  • wind-break cloth
  • or frost cloth
  • or clear plastic.


Photos: Bread tray cloche at Heartwood Walnuts, in the Richmond Region, NZ.


CREATING WARMTH - Wind-up covers

Mike Hancock's wind up covers allow you to create a warm microclimate. 

You roll the plastic cover up or down to change  warmth and  air circulation (wind).

They can be used to protect plants from frost. 

The photo is taken in his Hamilton back yard. 

Download instructions on how to make these covers below. (Thanks for sharing, Mike!)


CREATING WARMTH: A back yard green house in Hamilton made from recycled windows, laserlite and a shower partition with recycled wood and metal frame.


Beautiful greenhouse in Hamilton built using spare bricks found on site and second-hand windows. 


Traditionally these are made of glass, and are used for warmth and protection for a single seedling in the garden.   Some of the newer plastic ones have adjustable vents in the top. 


You can make your own for free!

Use a clear plastic bottle - ideally soak the labels off (although the snails will eventually eat them off!).

Put the lid in your council recycling bin.

Use tin snips, a knife or box-cutter to cut the bottom off.

Put the bottom in your council recycling bin.

Put the bottle over the seedling in the garden.

Secure it with a garden stake - try to avoid damaging the plant's roots. 

The stake will stop the bell cloche from being blown away.  




As with all cloches, keep an eye on the plant - not much rain will get in, so you may need to water the plant.


The sawmill on Tasman Road (behind The Base) offers free sawdust.

Sawdust makes a great mulch: spread it thickly over moist soil to keep the moisture in, and reduce the need to water so much over summer. Sawdust is also a good source of carbon when making compost.

Most sawdust is from untreated timber, but it is a good idea to check. (Treated timber contains toxic chemicals and should be avoided for food gardens.)

Where to get Compost & Mulch Ingredients

Composting needs a mixture of green (nitrogen rich, wet) and brown (carbon rich, dry) ingredients. 

Carbon rich materials make good garden mulch.  

Aside from what you can produce in your own garden and kitchen, there are many free sources of these materials which you can often get just by asking nicely.  Find businesses by looking up the Yellow Pages telephone book. 




Used hay bedding from guinea pigs, chickens, rabbits etc.

Nitrogen and Carbon

     Pet shops – may come with newspaper which should be roughly shredded.


     Neighbours who keep these animals

Used sawdust from the bottom of bird enclosures (aviaries)

Nitrogen and Carbon

     Pet shops


Coffee grounds



     Petrol stations that sell coffee

     Workplaces that use ‘real’ coffee

Tea leaves and bags, vegetable scraps




     Work places


Grass clippings


     Neighbours who mow their own lawns

     Lawn mowing contractors

     School caretakers

Manure – sometimes there is a small charge, eg $2 a bag. 


     Pony clubs

     Racing clubs

     Horse breeders – Matangi, Cambridge…

     Sheep farmers – under shearing sheds

     Livestock sale yards



     The beach

NB It is illegal to take it from a Marine Reserve

Torn newspaper, cardboard, egg cartons



     Most retail stores

     Neighbours’ recycling


Shredded paper


     Workplaces with confidential information

Tree Prunings, twigs, sticks


     Arborists, tree pruners

     Gardening companies

     On the ground in public parks

Dry leaves


     Arborists, tree pruners

     Gardening companies

     On the ground in public parks

     Neighbours with deciduous trees



     Arborists, tree pruners


Untreated sawdust


     Sawmills, eg the one in Tasman Road

Wood ash


     Neighbours with fires (could barter)

Shells (crush them, or burn then crush)


     Seafood restaurants

NB It is illegal to take shells from beaches in the Waikato region


You can also try web sites offering free resources such as: and

Download this information as a PDF:


Clay Soil

Clay soil tends to set like concrete & crack in summer, then holds water in winter, making it tough going for most plants.  On the up side, clay often contains lots of nutriments.

One way of improving clay soil is to add gypsum.  The thrifty way of doing this is by recycling off-cuts of gib board, which is has a high gypsum content.  Gib board is used in the building industry to line walls, so ask at a local building site whether they have some spare - you'll be saving them rubbish disposal costs, so it should be free.   

If you also have weeds to deal with, lie the gib board on top of the soil, making the weeds rot down in the process. Alternatively, break the gib up and dig into the clay, preferably with compost.  

Gypsum also has several other benefits such as reducing the swelling and cracking of soils.

So how does it work? Gypsum, also known as calcium sulphate, encourages clay particles to group together and thereby improve soil structure.  This then helps water and nutrients move into and through the soil. 

It's a fairly neutral product: it doesn't raise the soils pH and so is safe to use in situations where using lime would send the soil pH too high.

Here's an article about a gardener using gib board and other types of recycling in her garden.

(Thanks Bob Longhurst for the technical information)


At the soil and weeds workshop we learned that the Waikato has a variety of different soil types - even within Hamilton there are a wide variety of soils.  The wild plants that flourish in your garden can tell you about the state of your soil. 

The handouts from the workshop are available to download below, thanks to the tutors Bob Longhurst and Clare Jackson!

Right: Bob demonstrating one of the soil texture tests 





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