Celery and Celeriac

 Celery and celeriac are the same plant (Apium graveolons) with the former (var. graveolons) grown for its stalks and leaves and the latter (var. rapaceum) for its root. We regularly eat celery raw in salads and cooked in dishes such as curry, lasagne, soups, etc but have never tried growing them. Celeriac, on the other hand, is largely unknown to us - I think we've cooked them only once or twice.

Celery and celeriac are marshland plants requiring moist fertile water-retaining soil. They do not appreciate drying out so I decided to try growing them in Large Salad Planters available from Greenhouse Sensation. These planters have a built-in reservoir that feeds water and nutrients to the plants/soil using capillary feeder mats. The water/nutrient reservoirs need topping up on a, roughly, weekly basis depending on local temperatures, wind speeds, humidities and plant/foliage growth. I have used them for a number of years to grow salad leaves, jalopeno and sweet peppers, and aubergines in my polytunnel as they ensure a constant 'on-demand' supply of water and nutrients.  I use a coir-based medium which has excellent water-retaining properties. The large salad planter has a planting area of approx 100 x 50 cm.

Seeds were planted in small coir pots made out of newspaper/toilet rolls and placed in a propagator (20 ℃) with overhead lighting (light needed for germination) in late March/early April. Germination is slow (weeks) and variable. Seedlings were potted on into 7 cm pots and placed outside in early May to harden off. Both celery and celeriac would be grown outside in Salad Planters. Finally, the Salad planters were potted up with celery (left below) and celeriac (right below). Only 10 celeriac plants developed sufficiently for planting out so a few celery plants filled up the end of bed.

Celeriac plants, Greenhouse Sensation, Large Salad Planter
Celery plants, Greenhouse Sensation, Large Salad Planter

The celery was a green self-blanching variety but I don't have a record of the celery or celeriac varieties.

Six weeks later the celery had progressed nicely:

Celery Plants in Large Salad Planter
Celery Plants
And the thinnings were providing the first harvests:

Celeriac was coming on nicely but it would be a couple of months before they were ready for harvesting.

Celeriac was pest-free and harvested from September onwards:

Celery was harvested throughout the summer but did suffer from blight later in the season. Two celery plants (leaves and stalks) were dried in our dehydrater and ground to provide sufficient seasoning for the rest of the year. 

I will be growing both vegetables next year - this time I'll note down the varieties and yields

PV Generation - 15 years

The PV panels installed on my roof have now been running for 15 years; switched on 9th December 2005. Apart from an inverter failure in 2015, that took 6 months to fix, the system has been maintenance-free. Annual PV generation (kWh) is shown graphically below.

Renewable energy, photovoltaics, PV, renewables, carbon footprint
I would expect an reduction in annual electricity production with time as the efficiency of the PV panels decreases with age. This loss in efficiency has been offset by an increase in sunshine hours, especially in the summer months. More details on this in a later post.

The carbon intensity of UK grid power is about 500g/kWh. Solar PV has a carbon intensity of about 50g/kWh which includes embedded carbon intensity (i.e. mining, manufacture, installation, etc). Over the 15 year operational time period, my solar PV has generated 58,300 kWh which equates to 26 metric tonnes of CO2 mitigation (about 7 metric tonnes of carbon).   

Garden Shredders

Bob Flowerdew is dismissive of garden shredders ("shredders make materials more suited for composting but are dangerous, noisy and irksome to use"); an opinion he has oft repeated on Gardeners' Question Time (GQT) with comments like as "I cannot see the point of them".

As with everything in life, things are more nuanced and a bit more complicated than that. For a start, his garden - at around an acre - is much bigger than most people's so he has plenty of space to (i) allocate to composting, and (ii) provide material for his compost heaps. Those of us with small town gardens are more limited on both counts, especially if we want to devote most of the garden to leisure and/or growing flowers & vegetables. My garden, which is above average for an urban garden, is about 0.05 acre or 1/20th the size of Bob's!

I bought my first shredder in 2012 when I got serious about composting. Due to the lack of garden space and a requirement to compost kitchen waste (including cooked food), I went down the 'hot composting' route buying my first HotBin. In addition to my own garden waste, I was also taking in neighbours' green waste to avoid them making regular trips to the municipal waste depot. Shredding increases composting rates by coarsely chopping garden waste to increase surface area and disrupt plant cell walls to facilitate microbial breakdown of the organic matter. Shredding also reduces the volume of garden waste by about 50% to minimise pre-composting storage requirements. For example, a neighbour recently had their hedge trimmed professionally and I was able to deal with the 2 cubic metres of cuttings with ease by shredding and storing prior to adding to my composters.

There are two types of shredder for small gardens:

Impact Shredders have a rotating cutting blade through which the garden waste is hand-fed. These shredders are the cheaper, lighter but noisier of the two types.  The cutting blades cost around £20 and are reversible to double their lifespan before replacement or resharpening. These shredders are suitable for both woody (hard) and green (soft) garden waste and are my preferred choice for preparing garden waste for composting. They also make short work of stale loaves of bread! Whether for wood chipping or chopping green waste, this type of shredder is a good all-round choice.The Bosch AXT 2200 is a typical example.

Roller or Drum Shredders have ridged rollers/drums that draw the garden waste in so are easier (less tiring) to use and best for larger volumes. They are quieter but heavier and more expensive. Maintenance is lower as the cutting/crushing mechanism does not require regular replacement. This type of shredder is great for woody material such as branches but less good for soft green material which can cause the drum/rollers to jam. Buying a machine with a reverse option is a good choice. The Bosch AXT 25 TC Quiet Shredder is a typical example.

In the foreground is my new Bosch AXT Rapid 2200 shredder purchased in November 2020. In the background is the defunct machine it replaced. My first AXT 2200 was bought in 2012 and did sterling work for just over 5 years before the motor burnt out. The second machine (in the background) was bought in 2017 and lasted 35 months before developing an electrical fault with the on/off switch. These Bosch shredders come with a 2-year guarantee so I thought, that's it, I'll have to buy a replacement which I did.

Composting, green waste, shredding

What I hadn't realised was you get an extra warranty year if you register the machine which, fortunately, I had done back in 2017. I got in touch with Bosch UK and they arranged for a courier to pick up the shredder the following day. Less than a week later, I received an e-mail saying they could not fix it and would send a brand new shredder. It arrived a few days later. That is top notch service. Needless to say, I've registered the current machine and the replacement!

Pricewise, the 2012 shredder cost around £150, the 2017 machine about £180 and the 2020 unit about £200.

Is a shredder a worthwhile investment? I process about 15 cubic metres (15,000 L) of garden waste per year to produce approximately 1.5 to 2 cubic metres of finished compost. I would not be able to process these quantities without a shredder.


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