Common Hill Nature Reserve - March Update

 We paid one of our regular visits to Common Hill Nature Reserve on 22nd March. See here and here for January and February reports. The trees are still waiting to leaf up but the sward is greening up nicely as this view from the corner near the main North meadow shows...

...and looking back towards the entrance...

...and the view towards Haugh Wood as we leave the top of North Meadow...

...crossing the footpath and looking up Monument Hill towards the anthills...

...then climbing Monument Hill and looking back...

...before popping into Old Cider House...

...and, finally, from the gate looking up the slope of Round's Meadow...

...where they have been installing new stock fencing...

It was a bright sunny afternoon with a coolish breeze and a temperature of around 18-19 ℃.

Flora (flowering):
  • Lesser Celandine - widely distributed
  • Cowslip - single specimen
  • Primrose - widely distributed
  • Dog's Mercury - widely distributed
  • Daffodil - single group, garden escapee
  • Dandelion
  • Barren Strawberry
  • Sweet Violet - widely distributed
Most flowering plants seen in North Meadow

  • Three butterflies spotted but not identified. One white seen in the distance and two red/brown - possibly Comma and Peacock - seen once and fleetingly
  • Woodpecker heard in the distance (from the direction of Haugh Wood)
  • Robin
  • Wren
  • Blackbird
  • Buzzard
  • Chiffchaff
  • Pheasant
  • Wood Pigeon

New Arrivals - Frogspawn

 First frogspawn sighting of 2022 (23rd March) in our small garden pond...

...or in close-up...

No sign of the parents!

The appearance of frogspawn is an annual event. Unfortunately, we haven't kept past records of first sightings; anecdotally, this year seems to be later than usual.

The arrival of frogspawn in the Spring is another example of phenology. You can record these events at Nature's Calendar, a citizen science project run by the Woodland Trust, where I have already recorded our first sightings of Snowdrop, Peacock & Comma butterflies, as well as Frogspawn.

Forest of Dean Sculpture Park - Taster Session

Returning from a short holiday near Chepstow, we stopped off at Tintern Abbey (raining) and Beechenhurst in the Forest of Dean (still raining). It stopped raining when we got home. Despite the rain, we enjoyed looking around Tintern Abbey (it rained last time we were there if I remember correctly) walking a short section of the Sculpture Trail at Beechenhurst. Did I mention that it rained most of the day?

The Sculpture Trail gets a refresh every now and then so is always worth a return visit. Due to the inclement weather, we only managed the first few sculptures but we will definitely be back...

...and back to the car park via a short-cut though not before I'd slid down a muddy bank on my backside!

Wild about Daffodils


Just over the border in Gloucestershire, in an area known as the Golden Triangle, is the best place to see wild daffodils in this part of the world. The villages of Kempley (19-20th March 2022) and Dymock (26-27th March 2022) host daffodil weekends where you can be guided or just wander freely through woods and fields filled with the smaller unpretentious wild version of the daffodil. The first two photos were taken in Betty Daws Wood where carpets of yellow daffodils spread out before you as far as the eye can see. To be honest, photography - and especially my photography - does not do justice to this spectacular display.

Wood anemone also put on an impressive display but do get overshadowed by their more colourful companions...

A short walk from Betty Daws Wood are Gwen and Vera's fields...

... which get their very own Wiki page! I'd always assumed one of the fields belonged to Gwen and the other to Vera once upon a time, but maybe Gwen & Vera owned both fields or there is another explanation entirely. In any case, the two fields are part of a nature reserve managed by the Gloucestershire Wildlife Trust.



"What is that?", I hear you ask (rhetorically). It appeared today - in the kitchen garden - during a sunny period; the sky was blue and cloudless. My 'dash' came to a full stop. I'll need my phone: a close-up photo of a comma will look great in a blog post...

First Garden Butterfly of 2022

 Following on from our first butterfly of 2022, I can now report on the first 2022 butterfly to appear in the garden on March 18th... with 2021, it was a peacock butterfly. The butterfly spent time on the paved patio, warming itself in the early spring sunshine (16 ℃ and sunny at 1410 hours when the photo was taken).

This sighting beat last year's sighting by a few days and the butterfly looks in better condition than the 2021 version - possibly down to a milder winter.

First Butterfly of 2022


We have just returned from a short holiday near Chepstow having passed through the Forest of Dean on our way there. One of our stops was at Cannop Ponds; two pre-1830 ponds built to supply water to a waterwheel at Parkend Ironworks

14th March 2022 was a warm sunny day; in fact the warmest March day so far in 2022 at 16 ℃. Mary spotted a butterfly fluttering by. Fortunately, it landed on a nearby stone where it stayed for sometime warming itself in the sunshine. I took a quick snap on the camera phone (above) while Mary stealthily crept closer to get this much better photo on her phone...

...a Comma. These butterflies hibernate so it was not unusual to see it in its natural habitat (open woodlands and wood edges) at this time of year.

Last year (2021), we spotted our first garden butterfly (a Peacock) on 21st March in the polytunnel.


I'm not sure when I got my first HOTBIN composter; I remember buying it from Tony Callaghan, inventor of the HOTBIN, before he sold the patents and company to DS Smith in January 2016. Tony then moved into biochar R&D/manufacturing with his new company SoilFixer.

I bought my first lot of biochar from Soilfixer in 2018 and they are still my preferred supplier. Why? Because the product is top class and Tony is not only enthusiastic and knowledgeable about biochar but always available wth plenty of helpful advice.

[Note: in 2019, I received a free prototype Supercomposter from Tony for evaluation, comment and critique. I will discuss my experience with this equipment in a later post]  

What is Biochar?

The International Biochar Initiative (IBI) defines biochar as 'the solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment'. In essence, it is a form of charcoal used today mainly as a fuel for BBQs. Biomass (e.g. wood, straw, coir) heated in air is termed combustion and produces mainly water, carbon dioxide and mineral ash. When biomass is heated in an inert atmosphere (i.e. oxygen-deficient) then it is called pyrolysis and yields predominantly biochar, bio-oil and bio-gas (aka syngas). Combustion and pyrolysis both release carbon dioxide (bad!); however, the latter produces only half as much (good!).

Biochar Benefits 

For the gardener/farmer/horticulturist, the most important use of biochar is as a soil improver or amendment. Qualitatively, it is acknowledged that soil health improves when biochar is added, especially when added to poor quality soils. Quantifying the benefits, in order to decide whether it is a cost-effective intervention, is more difficult because: (i) biochar is not a uniform standardized product due to variations in the biomass feed, pyrolysis conditions and post-pyrolysis processing/treatment, (ii) standardising field trials to directly compare with/without biochar is hard, and (iii) biochar is usually added as a co-mixture with compost, fertilizer, nutrients, etc.  

There have been over 15,000 papers on the use of biochar in agriculture so it is, indeed, fortunate we have accesss to a meta-analysis of meta-analyses that summarise the results of all these studies. The graphic below is taken from 2021 paper by Schmidt et al. See the link to read the paper in full.

Biochar is slightly alkaline (pH 7-8) and seems to work best in sandy acidic soils although it is still benficial in other soil types. Biochar has a strong effect on root development and mass - perhaps unsurprising since it is added to the soil! With a larger, more-developed and active root system, the plant makes better use of available nutrients and water resulting in higher plant productivity and crop yields. Greater root mass leads to increased soil organic matter and net removal of atmospheric carbon dioxide.

There is good evidence biochar works better if primed with nutrient-rich additives such as garden compost, animal manure/slurry, urine and even artificial fertilizers. Nutrients are adsorbed onto the biochar surface; this reduces the loss of nutrients by leaching and allows the nutrient-primed biochar to act as a slow-release fertilizer.

Finally, adding biochar to soil improves water retention by the soil (good) without the soil becoming waterlogged (bad). While anecdotes are not evidence, in my experience I do not have to water the kitchen garden as much as I used to do.

Biochar and Climate Change

Biochar has the potential to sequester significant amounts of carbon into the soil where it will stay for centuries. It is, therefore, a simple, tried-and-tested method for mitigating climate change. It has been suggested it could offset 12% of the world's emissions of carbon dioxide though this seems a little optimistic to me. Making biochar from waste streams (wood offcuts, straw, plant residues, etc) does seem a no-brainer considering the added benefits to soil health and increased food crop yields.

1 kg of biochar buried in your garden is equivalent to offsetting about 3 kg carbon dioxide.

How to Use Biochar

Biochar can be worked directly to the soil prior to planting but I prefer to add it to my hot composting bins. This primes the biochar with nutrients and turns it into a more effective soil amendment. 

I use a 50:50 mix of Soilfixer Compost Activator (Humification Agent) and Biochar Granules (0-10mm), adding about 60 g with every 6 litres of garden/kitchen waste. An old laundry bottle cap serves as a useful measure for 60 g (see pic at top of page). The compost activator assists with the composting process and the biochar acts as a sponge for nutrients and micro-organisms. By using locally-sourced biochar (from Gloucestershire) primed/innoculated with garden compost from my garden (and some neighbours' gardens), the resulting compost is optimised for growing plants in my garden.

Is Biochar a Cost-effective Soil Amendment?

On a commercial (farming) scale, this is a very important question. If the cost is covered by increased crop yields while also improving soil health and making the soil more resilient to adverse weather events (floods & drought) then cost benefits start to accrue. Unfortunately, the cost of manufacturing biochar is currently too high for routine use on commercial farms. Scaling up biochar production should reduce prices and it would also help if the 'polluter pays principle' was universally applied by instigating a proper carbon tax (e.g. on fossil fuel-based fertilizers).

I use about 80 kg biochar products per year at a cost of around £195. This offsets my annual carbon footprint by about 250 kg (a quarter of a metric tonne) of carbon dioxide equivalent. Currently, this is much more expensive than paying into a carbon offset programme.

However, I am also benefitting from a healthier and more resilient soil, increased crop yields and reduced irrigation costs. Quantifying these benefits is difficult. Qualitatively, I know I am using less water for irrigation and crop yields seem to be higher (e.g. best onion crop ever last year). 

When I originally set up the kitchen garden, I had to remove lots of waste material and rubble and then infill with bought-in topsoil (recovered soil is sieved to remove large stones/roots and mixed with sand and compost). This was a very sterile environment for growing fruit and vegetables so I have been slowly improving the soil, year-by-year, by digging in garden compost initially and, more recently, compost and biochar. Soil tilth has improved and the colour has changed from light grey to dark grey.

As the soil carbon builds up in the soil, I will reduce the amount of biochar I add to my compost. At some point, I will need to send soil samples to a laboratory for analysis.

Finally, if you are interested in learning more about biochar and its benefits, then have a look at the Soilfixer website, FAQ and blog.


View from the Rear Window - February 2022

 January 2022 was warm and February continued along the same lines. See here, here, here and here. Indeed it has been a warm winter overall and, as a consequence, this wallflower has never stopped flowering over the winter months (Dec - Feb inclusive) ...

Of course, the main feature of the month was the three storms (Dudley, Eunice and Franklin) over the 7-day period from 16th to 22nd February. Our sheltered town garden experienced average wind speeds of 11 km/h (gentle to moderate breeze) and gusts up to 66 km/h (gale) over the week. This is a rare event since typical monthly average winds are in the range 3-5 km/h (light air) with gusts up to 45 km/h (strong wind).

The month of February started bright enough with a lovely sunny day. The sunlight giving the last blooms of the winter-flowering cherry an almost cloud-like appearance ...

The next picture shows the garden on the 19th February, in the 'lull between Storms Eunice and Franklin. The daffodils on the patio table had been moved to a less windy position on the floor before Eunice arrived and I had to pick up one of the small Xmas trees on the patio which had blown over. Otherwise, we escaped lightly...

On the last day of February, Mary wisely chose the morning to do some tidying up in the garden before the rain came at 2 pm...

Jobs in the Garden

1. Composting continues ad infinitum. The first lot of freshly-mown grass arrives to supercharge the hot bins

2. Finish pruning grapevines, pear and redcurrant and blackcurrant

3. Finish repotting wall strawberries. Some had become weedbound and others had died. After tidying up...

...there were still a few gaps. Fortunately, I managed to rescue a few dormant runners to revive in our heated Hydropod propagator ...

4. Plant out the newly-arrived bareroot raspberries - three each of Autumn Bliss, Glen Ample and Glen Prosen
5.  Lay seed potatoes (Blue Danube) out on shredded card to chit
6. Lots of general pruning and tidying up in the 'flower' garden
7. Still harvesting kale, broccoli, chard and spinach from the garden. Stored onions and potatoes still going strong!

February 2022 Weather

A summary of key weather parameters for February 2022 is presented in the table. Note: the minimum barometric pressure on the 18th coincided with the arrival of Storm Eunice.

February 2022

Weather Parameter



Average Monthly Temperature 

8 oC

Maximum Monthly Temperature

18 oC


Minimum Monthly Temperature

-2 oC


Number of Air Frost Days


Number of Hot Days (> 25 oC)


Monthly Precipitation

66.8 mm

Greatest 24 h Precipitation

11.4 mm

20th - 21st

Number of Dry Days


Monthly Sunshine Hours (estimated)


Average Wind Speed

7 km/h

Highest Wind Speed

66 km/h


Maximum Barometric Pressure (Sea Level)

1033.6 hPa


Minimum Barometric Pressure (Sea Level)

977.6 hPa


Average Barometric Pressure (Sea Level)

1025.3 hPa

The bar chart below shows the daily minumum and maximum temperatures throughout February. Daytime temperatures were remarkably constant over the whole month while nighttime temperatures stayed in positive territory except for the one night (11th). The temperature range and distribution was quite different to that observed in January. According to a recent scientific paper, high February temperatures have the strongest effect on inducing early flowering in plants and trees - so it will be interesting to see how this pans out in the months ahead.

The next bar graph plots the daily rainfall (blue) and solar radiation (orange) values for February. There were more rainy days (60%) than dry days (40%) with two-thirds of the monthly precipitation occurring between 13th and 22nd. The high ratio of rainy days meant some periods of low solar radiation (sunshine) although you can see the generally increasing trend as the days lengthen.

Finally, how does February 2022 compare with 2021 and 2020? Temperature-wise, this February was significantly warmer than the previous two years with a much higher maximum temperature and being almost frost-free.

February 2020 is looking like an outlier in terms of rainfall whereas the sunshine hours, number of dry days and maximum wind speeds are similar for all three years.

Hot Composting #1

As an avid composter, I've been meaning to write a series of articles on how I compost kitchen and garden waste in a small urban garden. I'm shocked, shocked to find my one and only post on this topic was 18 months ago!

From the start, I should emphasize that I will be mainly discussing 'Hot Composting Processes' as I believe this is the best option for urban gardens with limited resources of both space and organic matter (kitchen trimmings/waste and cooked food, lawn cuttings, tree/bush prunings, weeds, leaves, annuals, cut flowers, etc). Hopefully, you will learn more general principles of composting on your journey to Master Composter! Making compost is still very much an art although we know enough of the science for that knowledge to be useful. With a little training and plenty of practice, you will understand more than anyone else what works in your garden. 

There are, of course, alternatives if you have even more limited quantities of waste organic materials that you want to compost. For cooked/kitchen waste, try Bokashi. For raw kitchen waste and small amounts of plant waste, try a wormery or, even, a standard compost bin if you are the patient type.

What is Hot Composting?

In simple terms, the 'hot composting' process aims to provide optimal conditions for microbial activity to convert organic waste into rich garden humus as rapidly and efficiently as possible. To achieve this aim, the compost heap needs to spend periods of time at high temperatures (55 ℃ to 65 ℃), warm temperatures (40 ℃ to 55 ℃) and moderate temperatures (15 ℃ to 40 ℃).  A secondary, though important, objective is to destroy plant pathogens, fly larvae and weed seeds - this depends, largely, on achieving the highest temperatures.

Other essential factors to consider are moisture content, efficient aeration, pH, particle size, membrane/barrier disruption, range of materials and a biodiverse source of bacteria and micro-organisms. Consequently, the gardener should aspire to optimal conditions but be pragmatic enough to realise she/he will never reach that goal. Life is just not that simple or easy! You might say this is the First Law of Composting!

Commercial and municipal compost systems use the 'hot composting' process so it is beneficial for gardeners to understand, at least in broad terms, how they do it. First, they build the pile (the larger the better) using carefully sorted and graded (in terms of particle size, moisture content and C/N ratio) materials. The pile takes a few days to heat up to the target temperature (60-65 ℃) and is held at this temperature for a week or so. The temperature naturally drops to 40-55 ℃, when the composting process is optimal, and is kept there for a few weeks. Temperature and moisture content are controlled by turning the heap and adding water, if necessary. Finally, as the compost cools to ambient temperatures, the 'curing' or 'maturation' stage is entered, typically for a period of up to a month.

The HOTBIN® website claims to produce compost in 30-90 days (1 to 3 months) by achieving internal temperatures of between 40 ℃ and 60 ℃. While a useful guide,  this is only a guide. Realistically, I suggest you aim for a minimum period of 6 months to produce top-quality garden compost. This is still considerably faster than the 2-3 years using the cold composting method (see below). Your experience may be different because each 'compost process' is unique depending, as it does, on a large number of variables. While we want to mimic, as far as possible, commercial compost operations, we should remember they have access to a wide variety of input materials, along with machinery, monitoring and analytical instrumentation.

Note 1: Although I have not tried it, I suspect if you were to compost fresh grass mowings (source of nitrogen) with, say, shredded cardboard/paper (source of carbon) in the right proportions then some of the very short times - 2 weeks - claimed for 'hot composting' might be achievable. I have strong doubts about the quality of the final product except for its use as a mulch where the composting process continues al fresco!
Note 2: There are some products on the market claiming to produce 'compost' from food scraps in just 24 hours. The manufacturers of these products make plenty of claims but do not support those claims with evidence. As far as I can tell, these machines simply heat, blend and dehydrate kitchen waste and the manufacturers appear to have little or no understanding of how nature composts or, indeed, what compost really is. This equipment is expensive (£400-500?), requires electricity and consumables and is shipped from China. It is not a low-carbon alternative to home composting, whether of the hot or cold variety. Avoid! See here for someone else's critique on this type of 'composter'.

In summary, I aim to subject organic waste to a regime of temperatures as follows: >60 ℃ or more for 1-3 days and/or >50 ℃ for at least 7 days and, thereafter, to maintain a temperature of 40 ℃ or above for a further 21 days. Do I always achieve these objectives? No, but I always try to! I also include a maturation period of 6 months or more before using the compost in the garden.

Why Compost Hot?

First, consider the option of cold composting. This typically takes place at lower temperatures (ambient to 35 ℃) in an open compost bin and... takes a long time (18 months to 3 years) before you have anything that you can use in the garden. You are more limited in terms of what you can add to the heap (no cooked food, no weed seeds, no diseased plant material). Without some care and maintenance, there is a chance it could turn into a slimy smelly mess which nobody wants to deal with! This set-up can also be used for warm/hot composting if you are prepared to put extra effort into the process; e.g. careful selection of the type of organic waste (C/N ratio, moisture content) and regular turning of the heap to ensure adequate aeration. You will certainly need at least two bins so you can be filling one while the other is maturing and each bin needs to have a volume of at least a cubic metre to ensure sufficient organic mass to heat up and maintain the high temperatures needed for 'hot composting'.

Compared to the cold composting method, some of the advantages of 'hot composting' are fairly obvious.

1. Faster composting by virtue of the Arrhenius equation which describes the effect of temperature on the rate (speed) of chemical reactions. The 'rule of thumb' is that the rate of a (bio)-chemical reaction approximately doubles for every 10 ℃ rise in the temperature of the reaction. In other words, reactions at 20 ℃, rather than 10 ℃, go twice as fast (or take half as long). Moreover, if the reaction temperature is further increased from 20 ℃ to 30 ℃, there is another doubling of the reaction rate (halving of the reaction time); hence, a four-fold increase in reaction rate on going from 10 ℃ to 30 ℃. This relationship should be valid over the full temperature range seen in composting.

So lets compare cold composting (with an average heap temperature of 10 ℃) with a 'hot composting' regime of one week at 50 ℃ (equivalent to 16 weeks at 10 ℃), three weeks at 40 ℃ (equivalent to 24 weeks at 10 ℃) and four weeks at 20 ℃ (equivalent to 8 weeks at 10 ℃). The 'hot composting' process over eight weeks will be equivalent to 48 weeks of cold composting; i.e. six times faster.

2. Killing weeds, pests and pathogens by heat. Why 50 oC or more for a minimum period of 7 days? Well, everyone defers to this scientific paper in Weed Science. Who knew there was a scientific journal called Weed Science? The paper is very easy to read and I recommend it to you. For those short on time, this study looked at the temperature/time combinations needed to kill the seeds of annual sowthistle, barnyard grass, London rocket, common purslane, black nightshade and tumble pigweed. Tumble pigweed was the hardest to dispatch but only took 113 hours (just short of 5 days) at 50 ℃. At 60 ℃, all the seeds were dead after 3 hours. Hence, by my reckoning 7 days at 50 ℃ should see the job done but higher temperatures for a shorter time are even better.

Plant pathogens are more difficult to killinactivate or sanitize. I would only add 'diseased' material if the compost temperature is greater than 60 ℃ and likely to maintain this temperature for at least 4 days. There is a risk, of course, but I have never (touch wood) had a problem with recurring diseases from plant pathogens and pests or germinating weeds from the compost I produce. The other option is to dispose of such material through your general waste collection.

3. A wider range of micro-organisms are involved in the decompostion process. Mesophiles perform best below 45 ℃ whereas thermophiles perform best above 45 ℃. The composting process benefits because different micro-organisms can decompose a more diverse range of substrates (e.g. woody versus green materials). Higher temperatures also help with the chemical breakdown of substrates via acid hydrolysis.

4. A hot compost pile is handy for disposing of pests such as slugs and snails - as an alternative to drowning in beer or being killed by slug pellets, salt or nematodes.

In the next few posts, I will be discussing how to put 'hot composting' in a small urban garden into practice.

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