Boosting compost

General tips / questions on seeding & planting

Moderators: KG Steve, Chantal, Tigger, peter

User avatar
JohnN
KG Regular
Posts: 636
Joined: Thu Jul 27, 2006 5:45 pm
Location: Hookwood, near Gatwick
Been thanked: 2 times

What exactly is the difference between seed compost and, say, No 3. Can you add anything to seed to turn it into No3? I ask because I've got seed, but now cannot buy any potting-on compost. Thanks for advice.
User avatar
peter
KG Regular
Posts: 5842
Joined: Fri Nov 25, 2005 1:54 pm
Location: Near Stansted airport
Has thanked: 18 times
Been thanked: 33 times
Contact:

Personally I would expect seed compost to be finer.
i.e. passed through a finer sieve.
Also that it is properly sterilised.

Technically I believe it is how much, or how little, fertiliser is added.
Do not put off thanking people when they have helped you, as they may not be there to thank later.

I support http://www.hearingdogs.org.uk/
User avatar
Primrose
KG Regular
Posts: 8054
Joined: Tue Aug 29, 2006 8:50 pm
Location: Bucks.
Has thanked: 37 times
Been thanked: 281 times

Do you have any old compost left lying around in pots?
I had to improvise earlier, mixed some with some finely crushed earth from a bare patch of soil from my veg patch and used that. . Poured a little boiling water on it to sterilise let it drain and cool and so far all my seeds are coming up Ok Our soil is quite light and easy draining so probably wouldn't,t work with a clay soil.

Last autumn I never anticipated I,d be locked in because of a pandemic and unable to easily obtain gardening supplies in spring, so as long as I can keep up some kind of gardening will try and maintain an adequate stock of requirements. But old compost will definitely be kept in a separate container for emergency future use, topping up with garden soil or chicken manure pellets for some additional nourishment.
User avatar
Geoff
KG Regular
Posts: 5575
Joined: Thu Nov 24, 2005 5:33 pm
Location: Forest of Bowland
Been thanked: 129 times

Here are the original John Innes compost formulations showing seed compost has less loam and that 1, 2 and 3 are just increasing fertiliser.
JI Seed Compost
2 parts loam, 1 part peat, 1 part sand
To each cubic metre of mix, add
0.6kg ground limestone
1.2kg superphosphate
Potting Compost
7 parts loam, 3 parts peat, 2 parts sand
For JIP-1
To each cubic metre of mix, add
0.6kg ground limestone
1.2kg hoof and horn meal
1.2kg superphosphate
0.6kg potassium sulphate
For JIP-2
To each cubic metre of mix, add
0.6kg ground limestone
2.4kg hoof and horn meal
2.4kg superphosphate
1.2kg potassium sulphate
For JIP-3
To each cubic metre of mix, add
0.6kg ground limestone
3.6kg hoof and horn meal
3.6kg superphosphate
1.8kg potassium sulphate

You can substitute leafmould for peat. You can buy JI Base Fertiliser instead of using the items listed, the packet will tell you how much to use. This is often quoted as N:P:K 5.2:7.7:10. Fish, Blood and Bone is 5:5:6.5 so near enough to use instead.

What's a cubic metre (1,000 litres)? 100 litres is:
240 9 cm / 3½" pots
80 13 cm / 5" pots
40 18 cm / 7" pots
24 20 cm / 8" pots
18 23 cm / 9" pots
12 25 cm / 10" pots

Hope that helps.
User avatar
oldherbaceous
KG Regular
Posts: 13822
Joined: Tue Jan 24, 2006 1:52 pm
Location: Beautiful Bedfordshire
Has thanked: 254 times
Been thanked: 295 times

That is a very good post, Geoff, will be very useful to many.
Kind Regards, Old Herbaceous.

There's no fool like an old fool.
User avatar
Geoff
KG Regular
Posts: 5575
Joined: Thu Nov 24, 2005 5:33 pm
Location: Forest of Bowland
Been thanked: 129 times

I should have said. If you are mixing your own garden soil is likely to have less organic matter than the stacked turf loam of the original formulations so use a bit less soil and a bit more leafmould.
Post Reply Previous topicNext topic