[BumbleJo]

Ok so I've got some garden vouchers so am thinking of going mad and buying some enviro mesh or similar. All the brassicas are going in one long 4ft wide bed.  There'll be swede, kale, sprouts and psb.  Thought I'd do two lots of netting, one with the swede and dwarf kale, the other with the sprouts and psb to keep it more manageable and keep costs down as the sprouts and psb will be taller.  Question is how tall do folks think either group will be as I can then calculate netting requirements (when brain is fully working).  Also can instruct O.H. re height to make blue hoops.  Thanks!

[cadalot]

I bought netting that was 2m wide and my beds are 1.2m wide so I used a little math

Circumference of a circle C = 2 pi r  where r = radius = 600mm so

2 x 3.1415626 x 600 = 3769.9 say 3770mm

Semi circle = 1/2 C so 3770/2 = 1885mm or 1.885m so say 1.8m which leaves 100mm to roll up and peg down then I added 200mm either end to push into the ground so

My total length of blue pipe is 1.8m + 0.2 + 0.2 = 2.2m This gives me a hoop that is the right size for the netting and is high enough for most crops apart from sprouts.

After extending the frame for a couple of years I made larger hoops for this years based on joining two 2m wide netting together - it was way too high and difficult to stabilise so I reduced the height to something more practical - take a look on my diary and you will see what I mean

Left Photo a standard hoop arrangement
Middle Photo the too big frame that I then reduced - you can see why in the photo 
Right Photo - my taller hoop frame

Taller frame is around 600mm higher
 

[BumbleJo]

Wow! Cadalot, your maths is impressive! That's really helpful, will get O.H. working on blue pipe, whilst I can now work out the netting requirements.  Cheers!

[NewSteve]

Cadalot, are you telling us that frame is 4ft across and only 2ft high? It looks taller than that to me!

My PSB this year were certainly more than 2ft tall. I'm also planning to properly net them this year, so wondering how much netting I need!

[cadalot]

I have many heights and types of hoops and portable hoops - basically use the math and the width of the netting and you can derive the overall height and the length of blue plastic pipe required.

See examples below

For 2m wide netting total height = 600mm i.e. the radius = half a 1.2m bed width picture below - Portable short crops.
For 3m wide netting total height = 1.150m left picture above - Cabbages etc.
For 4m wide netting total height = 1.655m right picture above - Sprouts

I just allow 200mm each end to push into the ground and use a rebar to form a pilot hole, and I have marked where the ground should be on the hoops which aids in getting them all the same height.

Photo Left   - MkII and MkI Versions of the 1.2 x 1.2m Portable frame
  Middle      - Maths for height based on width of netting
Photo Right - MkIII Portable Hoop frame 1.2m x 1.2m with hoops from corner to corner
                    Hiding behind the pea bed

[NewSteve]

Ah, ok, so that was the 3m net. Looks like roughly what I need, thanks!

[BumbleJo]

So I now know how to calculate the size of netting (or rather husband does when I showed him your calculations) but I still don't know and it doesn't say on the seed packets, how tall does psb grow.  I'm thinking that'll be the tallest...sorry if I appear thick!  I remember last year didn't do it quite tall enough but obviously didn't remember the height!  Thanks.

[cadalot]

Nor did I until I put " how tall does psb grow" into Google and top one says can grow up to 4 feet (1.22m Tall)

http://organic-gardening-hq.blogspot.co.uk/2012/07/how-to-grow-purple-sprouting-broccoli.html

So remembering that the top of the hoop frame is a semi circle so it's like a dinosaur ( thin at the end, fat in the middle and thin at the other end)  you can now select a net width and thus a hoop height that will work for your layout on plan

Me I would go for the 4m netting as the leg length is 1.055m and the height in the middle is 1.655m

[BumbleJo]

Cheers Cadalot, yep I was thinking 4m wide.  Thanks for your help!

[cadalot]

No Problem - when down on the allotment I got a better photo of the MkIII Portable frame hoop and netting

A 1.2m x 1.2m using Decking Board way to heavy timber but I like the height it gives going from corner to corner. The weight of the base is why I have not fixed the netting to the timber like I have with the MkI and MkII Versions

It's not all about Hoops - Someone had dumped a blow-a-way Grow house frame on an area of the allotment that attracts rubbish so I rescued it and turned it into a fruit cage to go over my little cherry tree.

My allotment looks more like a camp site or a rock festival as I'm netting as much as possible to keep the foxes from digging everything plus the pigeons, magpies, mice and the occasional sighting of a rat early this year off and away from my vegetables.