Calculating soil requirements for raised beds

Answered by Jo Posted in Category Soil, Feed & Fertilisers

Dear Jo

Can you advise me on how to calculate the quantity of growing medium required, the best option to use and the need for anything additional?

Before I give you advice on the soil, I’m wondering if you have purchased Raised Bed Liners?  It is important to retain water and to prevent the compost and soil from running out onto the ground.

Now the growing medium.  We have a Soil Calculator link on the Harrod Horticultural website that works out the quantity of soil you will need but  I have done this for you - you will need 1500 litres of compost for the 3 beds in total.  Each 8’ x 2’ x 2 tier bed needs 0.62 cubic metres & the 1 tier bed 0.3, totalling 1.54 cubic metres.

Here at Stephanie’s Kitchen Garden we order a bulk delivery of Rolawn Vegetable and Fruit topsoil (available from the Harrod Horticultural Website) but these are sold in 1000 litre tote bags. 

At home in my mangers and raised beds I use multipurpose compost with added John Innes or topsoil and add some well rotted manure, or compost from the compost bin - this gives a suitable mix of soil and organic matter which will give your home-grown vegetables a good start. 

You will need to enrich whatever planting  medium you choose on a yearly basis by adding more organic matter such as compost and well rotted manure or Pelleted Poultry Manure to put valuable nutrients back into the soil.   We feed our plants Organic Liquid Fruit & Vegetable Feed throughout the summer on most of our crops on a weekly/bi weekly basis depending on the plant.

I hope this has helped you but if  you need any more information please get back to me or if you need assistance with ordering our Customer Services Team are available to help (0333 400 1500 (local rate)).

Best Regards


Horticultural Adviser


Meet the Author: Jo Blackwell
Jo Blackwell

Jo Blackwell is our well-established Horticultural Advisor and the Kitchen Gardener in Stephanie's Victorian style Kitchen Garden. She caught the gardening bug when she bought her first home 21 years ago. Her first greenhouse soon followed and she later gained an allotment.

As well as tending the Harrod Horticultural Gardens, she enjoys maintaining her own vegetable plot at home. She has been a gardener for Harrod Horticultural for over 4 years now and has a wealth of experience in organic vegetable growing, ornamental gardening and in using all Harrod products.


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