This is the second in a series on growing plants directly in home compost. Home Compost is traditionally applied to the soil as a mulch, in a layer an inch or two thick, to provide organic matter to improve the structure and properties. A gap will be left round the plants so that the compost does not make direct contact. Indeed, if searching the internet under “growing in compost, it would appear that the general consensus is that compost should form only a small proportion of the “soil” material and that it is not advisable to grow directly in compost. Although the evidence of your own eyes, during the season after composting plants such as tomatoes, pumpkins and squash, may show that at least some plants survive and grow well in pure compost heaps. It is also the case that no-dig gardeners who plant directly into compost, can often show a higher yield than obtained by those who dig and plant into the soil.

I planted into compost samples from two different dalek bins, a Green Johanna, Hotbin, Pallet bins (one which has over-wintered), and an anaerobic heap. All samples had been tested using the bag test to check that the composting process was completed. Cos Lettuce are being used as the test plant as they make good leaf growth and should photograph well.

At the end of the second week all of samples of the different composts have supported the growth of the lettuce with the exception of three. These failures where the result of external factors ( the dogs ate the compost and failed to replant the lettuce).

The three are being repeated with the pots moved out of reach of the dogs.

Schools or Allotment /Community Garden project Comparing growth in different composts could provide a simple but photogenic project for children at school or on allotments. A group or class could use pots of different composts to grow plant purchased in strips from the greenhouse or from the local garden centre. The compost could be commercially available comparing different brands, or peat and peat free or taken from home composting bins. If photos are sent to carryoncomposting@gmail.com we will publish them on the website, or they can be posted directly to https://www.facebook.com/carryoncomposting

Compost Awareness Week  2022   May 1 -7^th  

Schools  or  Allotment /Community Garden project

Comparing growth in different composts could provide a simple but photogenic project for children at school or on allotments. A group or class could use pots of different composts to grow plant purchased in strips from the greenhouse or from  the local garden centre. The compost could be commercially available comparing different brands, or peat and peat free or taken from home composting bins. 

At Stokes Wood Allotment we are using samples taken from dalek bins,  a Green Johanna, Hotbin, Pallet bins (one which has over-wintered), and an anaerobic heap. Cos Lettuce  are being used as the test plant as  they make good leaf growth and should photograph well.

If photos are sent to carryoncomposting@gmail.com  we will publish them on the website, or they can be posted directly to https://www.facebook.com/carryoncomposting

Planting in Compost

Home Compost is traditionally  applied to the soil as a mulch, in a layer an inch or two thick,  to provide  organic matter to improve the structure and properties.  A gap will be left round the plants so that the compost  does not make direct contact.

 Indeed,  if searching the internet under “growing in compost, it would appear that the  general consensus is that  compost should form  only a small proportion of the “soil” material and that it is not advisable to grow directly in compost.  Although the evidence of your own eyes, during the season after  composting plants such as tomatoes, pumpkins and squash,  may show   that at least some plants  survive and grow well in pure  compost heaps.  

Despite this, the  view remains  that compost  will “burn” plants heating  up as its  organic content  breaks down. This  tends to assume that immature compost is being used before the composting process has been completed rather than waiting  until it has  matured if it is to be used near growing plants.   Burning is also said to occur where manure-based compost has a  high phosphorus content or is used without  be left a season to mature.  As manure-based compost  will not be used by most home composters this should not be a problem and if manure is used at all,  it will only be in small amounts as an activator

Another reason given for not growing in compost is that has  inadequate water retention. This assumes the  grower does not  check the moisture  content of the growing medium and apply water if it is dry. Some also argue that the structure of the compost will not  support tall plants, which assumes tall plants are not staked and that in the garden roots will not grow through the compost layer into the soil. 

It is also said that the  pH  level might be unsuitable. This is easily checked  most vegetables favour a pH   between 6.0 and 7.0 or 7.5  and most finished home compost has a pH of 6-8 

The answer to the  question  might be provided by  no-dig gardeners who  plant into compost and can often show a higher yield than obtained by those who dig When starting a bed, a 15cm/6in compost layer will often be used  on top of layers of cardboard. The plants will initially grow in the compost eventually reaching into the soil which will provide support. Once no dig is established   vegetables beds, will benefit  should receive about  1in/3cm of compost each year.

This week there has been little change in the materials left in our Community Compost reception bin by allotment plot holders. We have continued to receive a range of weeds, still with considerable amounts of soil attached, and a few brassica stalks.  However, we have started to get artichoke plants  I have seen these being  grown on the site, but this is the first year they have been entrusted to the care of the Community composting bins.

As the pallet bins are now all full,  we have started using our decking bin. We have added a manure layer to give it a boost to compensate for the soil on the weeds  as we do not have many good greens at the present. 

Two of the pallet bins that had contained over wintered compost were moved to the Maturation bin although, they have been left since the autumn and  were matured when subjected to the smell test. Transfering to another bin breaks up any lumps and wet patches and when covered with plastic for a couple of weeks they dry and making it   easietr to sieve.

Three-sided Pallet bins offer no protection against rats, and it is a case of making a compost mix that does not attract too many visitors and regular turning of the contents to put them off. 

Over  wintered bins where the contents have not been disturbed for a couple of months are likely to containing evidence of visitors such as the burrows shown in the photos.  I knew we had rats round the plot and had seen the occasional visitor in the  three-sided pallet bins before, but this is the first time I have found burrows in the bin. The compost was moved  to the maturation bin and  no evidence of nesting  was found so it was just a visitor . More information is given on my Rats etc in compost page.  http://www.carryoncomposting.com/416920198

We have two Hotbin composters on the demonstration Site at Stokes Wood Allotments, Leicester which are used for composting the food waste from the café on Wednesday mornings and general waste from the allotments. Both have been in use over the winter and now need to be harvested to make room for new waste in  the busier spring period.

The lower regions of the one of the bins is shown in the photo with worms clearly visible. These first of these will be harvested next week  while the second will be used in a couple of weeks to start our 2022 Aerated Compost Tea.

These working bins can be seen on Wednesday mornings when the site is open to the public, at 2b Stokes Drive Leicester LE 3 9Bs, with breakfasts, hot cobs, tea and coffee  are available