Amount of Compost

NoviceHerbs

I have ordered 13 pots I know this unlucky but I have another pot spare which I will use as well so I will grow 14 new plants in the late spring

10 of the pots are  28cm  diameter dept 30 and height 27 cm

3 are 50 cm diameter dept 50 and height 36,. cm

Do you know how much compost and another ingredients I will need ( my compost as mentioned before is multi purpose compost.) This will be a be a big help for me to work out how much I need in advance. I did Order 100 litres but I guess that will not be enough now. It is hard for me to gauge litres

Thanks for your help

Fairygirl

100 litres is nothing. For that amount of pots that size, you'll need about  7 of 8 of those - at least.

Depending what you're growing of course. Anything staying long term in a pot needs more than just compost although that will be ok for the next few months.

NoviceHerbs

I am growing herbs , so what would would I need for perennials ?

pansyface

HERE IS A HANDY CALCULATOR FOR WORKING OUT THE VOLUME IN LITRES OF ANY GIVEN FLOWER POT.

http://www.aqua-calc.com/calculate/volume-truncated-cone

NoviceHerbs

Thanks for that pansy but I dont know what the top radius is , so I cant work out the  litres of compost i Need

Fairygirl

Why don't you fill a pot and see how far it goes  

I think you're over analysing everything to be honest. Most herbs like gritty free draining compost and sun. Water r them well, pick them and use them, and don't fuss too much over them. Some will take some shade. If they're in pots just move them if they're not happy. 

Perennials -  check the requirements of the  ones you want to grow, in terms of location and soil type etc, but most perennials are happier in the ground. 

BobTheGardener

Radius is half the diameter so is 14cm for your 28cm diameter pots and 25cm for your 50cm pots.

NoviceHerbs

I know the radius but its the top radius I wasnt sure of Bob which is required for the equations that pansy kindly let me have , thanks Fairy Its just I want everything  in hand when the herbs arrive

An estimate of the litres i need would be very helpful

Pete.8

As a rough guess - 1 cubic foot is 28 litres - the 1st lot of pots are roughly 1 cubic ft each if they were square which would be 280 litres - so I'd reckon about 200L should do it and another 100 litres for the bigger pots so about 300L in total or 6 x 50L bags - @ 3 for £10=£20

NoviceHerbs

Thanks Pete I think  I will order  another 400l to be on the safe side.

With regard to the grit how many kgs would I need  I assume I would use the grit for one of the large pots for rosemary  and 2 smaller ones will containt Oregano and Thyme unless you think either of these plants should have a bigger pot

Once again Thanks alot

Obelixx

Use a measure?   Multi purpose compost is not best for herbs.  They tend to like good drainage so you should use a John Innes no 3 which is loam based and maybe add a bit of MPC to give it some water retention and some coarser grit for good drainage.

Sounds counter-intuitive to mix like that but herbs hate wet feet unless they're mint and basil which like some shade and good drainage with a bit of moisture retention.   Think also about a gravel mulch on each pot to reduce the need to water and keep weeds down.