Compost is one of those words that can mean lots of things.
It can mean the pile at the bottom of the garden where you put a mix of lawn clippings, hedge and pruning shreddings, kitchen waste, chicken droppings and dead bedding plants. That wonderfully changes from a heap of waste to a rich organic matter.
It can also mean the stuff you get sterilised in a bag from the Garden Centre, that you use to fill pots.
And there are all kinds of mixtures in between the two. - But what do you use at the beginning of the season to sow your precious seeds? These will be your babies for the year, giving you food and flowers to brighten up and feed your summer.
This is one of the few times in the year that I don't use my own compost from my bins at the bottom of the garden, - the reason being that in my normal garden size bin, the compost mixture doesn't heat up enough to kill all the weed seeds, or seeds of some of the vegetable matter i've put in there. - This means that I don't know if my emerging seedlings are what I planted or a hanger on from the compost. If i'm planting up a shrub or potting on, those weed seedling are easy to spot and eliminate, but for seed sowing I resort to the garden centre stuff.
The top left is a John Innes (JI) mixture.- This is a soil (heavy) based compost that is a mixture of loam (sterilised soil), peat, sand and nutrients. These are great for planting up shrubs that will be in pots for a long time and hold water and nutrients well, but they can be too much for some of the smaller seeds.
The top right is a Coir, which I got in compressed bricks from wiggly wigglers, and rehydrated in a bucket (one of William's favourite jobs to help me with) This is great for making mixtures lightweight, but doesn't contain any nutrients or wetting agents, so not good if you let it dry out.
Bottom left is my local garden centre chain's cheap as chips multipurpose compost. - It is peat based, but is a decent texture and has some nutrients, but does contain clumps, - not great for helping small seeds come through.
The bottom right is my seed mixture. I use sieved multipurpose compost, with some John Innes and some coir added to reduce the peat content and increase water holding properties. This makes a great mixture with all the right properties for vegetable seedlings and annuals to get off to a great start.