Composting at the Garden

BRENTWOOD COMMUNITY GARDEN COMPOST NOTES (v3 July 2016; M.L. Russell)

DO WE HAVE COMPOST BINS IN THE BRENT WOOD COMMUNITY GARDEN?

We have 3 compost bins in our garden:

·         Bin 1 (round black plastic bin) – the most southern bin

·         Bin 2 (wood)– in the middle

·         Bin 3 (wood) – the bin on the north, closest to the tool shed

WHICH COMPOST BIN SHOULD I USE?

Always put compostables in BIN 1

·         Bin 2 is ‘partly composted’

·         Bin 3 is for ‘maturing’ compost – ready to use at fall cleanup

 We are composting in batches.  At or just before spring clean-up, anything in bin 1 is moved to bin 2. 

At about the end of July or early August, the contents of bin 2 are moved to bin 3.

WHAT DOES A COMPOST PILE NEED TO WORK?

For Aerobic composting, which is what we do in the garden, the pile needs

·         greens – high in nitrogen

·         browns – high in carbon

·         air

·         water

WHAT CAN BE PUT INTO THE GARDEN COMPOST?

In our garden compost put only

·         greens

·         browns

WHAT IS A GREEN?

Greens are high in nitrogen and include anything that was harvested when it was green or ripe/juicy.

·         lawn clippings harvested when green

·         leaves blown down in summer when green

·         coffee grounds

·         green vegetable scraps, fruit, fruit skins

·         grass, hay

WHAT IS A BROWN?

Browns are high in carbon - harvested when dead, brown, and crispy. 

·         shredded newspaper

·         finely shredded cardboard

·         dry, brown autumn leaves

·         straw

·         sawdust (not from painted, treated or pressure treated wood)

Use a paper shredder rather than just ripping up paper and cardboard – the smaller bits compost much faster.

 Avoid leaves from trees with clumps of seed like Manitoba maple – will cause a huge weed problem when the finished compost is spread.

WHAT ABOUT MEAT/DAIRY/BAKED GOODS/GRAINS?

Do NOT compost these items at home or in the garden.  You will:

·         attract vermin like mice and possibly even dogs/coyotes

·         create an awful smell

·         potentially breed pathogenic bacteria while things are composting.

HOW MUCH GREEN?  HOW MUCH BROWN?

A simple rule of thumb is ‘equal amounts’.  This, however, can be misleading.  Our experience is that you have to think about the ‘equal amount’ – volume? or mass?

If the greens are light and fluffy you can add about an equal volume of browns BUT, a bag of fresh, wet grass clippings contains HIGHLY compressed grass and is MUCH heavier than a bag of brown leaves.   An equal volume of browns is just not enough – aim for roughly equal weight.

Excessive greens make the pile very smelly – the cure is to add browns and aerate/turn like crazy.

WHAT ABOUT COMPOSTING WEEDS?

Do not compost weeds if:

·         seeds have formed

·         the weed spreads by rhizomes (e.g., quack grass)

·         they are noxious weeds -  (place in garbage bin in playground next to community garden or take home to your black garbage bin)

Alberta legislation on noxious weeds can be found at

http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/acts6156

You can find a great identification field guide at

http://open.alberta.ca/publications/6740590

WHAT IF THE PLANT IS DISEASED?

Never compost any plant that you suspect is diseased as the bacteria, fungi or virus affecting the plant will not be killed.

WHAT MAKES A COMPOST BIN/PILE SMELL BAD?

It shouldn’t!!!  Bad smells indicate problems.  Most commonly these are:

·         too many greens and not enough browns

·         too wet

·         not adequately aerated.

HOW DO WE BUILD THE PILE?

·         First ‘fluff’ (turn) the pile. 

·         Alternate layers of greens and browns, maximum about 4 inches thick per layer.  Then mix the layers together.  Make sure that the 1:1 by mass ratio is maintained.

·         Add a handful of soil after layering so that the pile has some micro-organisms to start the compost process. Once it starts heating up no need to add more. 

As decomposition takes place, the pile will settle and squeeze out the air – killing the bacteria and fungi that make the compost (‘decomposers’).     That is why it is important that aeration and turning gets done to introduce air spaces.  Aerate (fluff that pillow! – mix, fold sides to centre) twice a week if you can.

CAN I BRING MY KITCHEN OR GARDEN WASTE TO THE BCGG BINS?

·         No, we do not have the capacity to handle this.

·         The BCGG compost bins are used only for garden waste from the BCGG - PLUS coffee grounds (and ripped up used  paper coffee filters which some volunteers bring from Starbucks)

·         However, if you happen to munch a fruit or veggie while in the garden, you can put your

apple core, banana skin, etc. in bin #1!

 WHAT ABOUT EGGSHELLS?

·         Compost these at home.  

Eggshells don’t actually ‘compost’; rather the minerals in them break down and leach into the pile.  It helps if they are crushed first.  They add useful trace minerals to the mix but it takes a long time and chunks of shell may still be visible when the compost is sifted.

WHAT ABOUT ‘COMPOSTABLE’ BAGS?

Bags marked ‘municipal compostable’ are only compostable in the City green box program.       

·         Don’t add these bags to either the garden compost or your home compost

WHEN SHOULD WE ADD WATER?

·         Don’t add water without thoroughly turning/fluffing the pile and checking the feel in case under layers are wetter than the top.

·         The compost should feel damp, not wet:  like a wrung- out sponge.

·         If the pile gets too wet:

o   toss to aerate,  (or use Wingdigger to aerate)

o   add some dry browns (in a pinch, shredded paper) to absorb the moisture.  When you add the shredded paper you are also adding browns.  IF you add too many browns need to add more greens

Calgary is so dry and our garden so windy that a pile that is too wet will dry out on its own most of the time.   If we have a lot of rain making things too wet, just cover the pile!

WHAT ABOUT AERATING/TURNING THE PILE?

Aerating and turning are critical so that the bacteria can work. Compost left to itself (for example – black compost bins that are not aerated) will take longer to decompose (i.e. 1 year).   

At minimum for 2016, the piles need to be turned at every garden work party.  If possible, some volunteers will turn/mix the pile at least once a week.  Turning the pile means:  mix, fluff right to the bottom and blend the layers.  Mix and toss stuff from the sides to the middle and the middle to the sides.  Can use Wingdigger, garden fork or whatever.  Make sure that stuff from the bottom is pulled up to the top. 

·         Think “fluffing a pillow”; folding flour into egg whites!

WHY SHRED PAPER OR CUT UP GARDEN WASTE?

We are doing ‘aerobic’ composting (requires air – oxygen).  Shredding paper (narrow but not more than about 4 inches long) or cutting up garden waste increases the surface area exposed to air.  The pile composts faster and is much easier to turn and aerate.  Aim for “as long as your hand”.

IF SHREDDING IS SO GOOD, WHAT ABOUT USING A BLENDER?

Alas, this makes quite a dense sludge.  Particles are too small – they don’t aerate.  Chop up your left over veggies instead.  Aim for pieces no long than a finger and no wider than the width of a finger.

DOES COMPOSTING ONLY WORK IN THE SUMMER?

Composting works all year round.

·         In warmer weather, the mix of greens and browns activates thermophilic (heat loving) micro-organisms – which is why the pile really heats up (those bacteria really love those greens!)

·         After about 8 weeks, conditions start to be more suitable for mesophilic (middle temperature loving) bacteria.  The material in the middle bin #2 continues to compost but cools down as the mesophils take over.

·         The ‘finished’ compost from bin #3 may be added to the garden beds in November or left until spring.  It continues to compost slowly over winter.

·         Material added to the bin in the winter will also compost very slowly, but will need to be tossed to aerate unless frozen solid – as soon as thawed enough to aerate or turn, need to do so.

WHEN IS COMPOST READY TO ADD TO GARDEN BEDS?

·         The finished compost looks quite a lot like soil.  It doesn’t heat up and it smells like earth. 

·         “Mature’ compost is best left for several months before application so that the ‘decomposers’ settle down or die off.

·         Usually best to apply in fall after harvest, or at least 2 weeks before planting in spring (some seeds/plants are sensitive to the ‘decomposers’).

DOES COMPOST HAVE TO BE SCREENED BEFORE USE?

·         Finished compost can be used without screening.  BUT, it may contain a lot of twigs, rocks and incompletely composted lumps of pine cone/paper etc.  Screening gives a much more evenly textured product. 

·         A compost screen is a frame that contains ¼ inch or ½ inch ‘hardware cloth’.  ‘Hardware cloth’ is a tough metal mesh that can be purchased at hardware stores.  You can make your own screen or buy one at Seedy Saturday – most garden centres don’t carry them, or if they do – at a price you probably won’t want to pay.

WHERE CAN I LEARN MORE?

There are a lot of resources out there.  My favorite book is:

Composting for Canada by Suzanne Lewis (Lone Pine Books).  You can find it at the public library or purchase it for about $18.00.    It covers the many ways you can compost and is designed for Canada.

It is very practical and accessible for beginners but also useful for experienced composters.