Improving the soil

The main soil improving ingredient is good old organic matter. If your garden is new then you probably won't have any garden compost around. The chances of scrounging any is negligible, if some one has bothered to make it, then they won't want to give it away.

Organic matter is needed in bulk, not as concentrated chicken manure pellets and the like, though these are good for adding nutrients.

Rather than spend huge amounts of time and energy digging it in (you can do this of course, but I'm assuming that you don't want to), use organic matter when planting and then after as a mulch.

Using a good soil conditioner when planting can gain a year or so of growth on plants compared to direct planting into the soil. Get them off to a good start and they'll never look back (Although this is not a universal panacea, no amount of soil improver will help the plant that is simply in the wrong place). Use the conditioner as a halfway stage between the soft compost of the pot the plants have been grown in, and the harsh reality of your garden soil.

Soil conditioners

Well-rotted farmyard or horse manure  

What's it like? - The best of all for my money. It conditions the soil and adds nutrients. Make sure it's well rotted, it should smell earthy, not pooey (please excuse me I have a small child) and be dark in color. If it's recently out of the animal it will smell like it, be mid brown rather than dark brown or black and probably have recognizable pieces of grass and straw mixed in. Don't use it without composting it for a few months. If it's like this, the poor little plant roots will curl up in disgust.

Where to get it 

    Sometimes available in bags from suppliers of topsoil and other bulk materials

    Garden centers

If you live in or near the countryside, you may see bags for sale or even given away (I know of a riding school that has to bag it and take it to the local skip - criminal!). These sources may be of fresh manure, be sure to let it rot down before using it. I used to get my supplies from a local farmer who delivered a trailer load locally of about 2 tonnes for £25 (he's run out now).

Garden compost

What's it like? - Second only to farmyard manure, but not as many nutrients. If properly rotted it won't be at all unpleasantly smelly and shouldn't contain any recognizable plant material bar the odd bit of twig. How to make compost to gladden the hearts of a worm

Where to get it  

    Make it yourself.

    Bulk materials merchants and garden centers.

Peat and Old Grow Bags

What's it like? - Generally very clean and pleasant to handle. Large compressed bales are best value (you may need help in handling them). Very good as soil structure conditioners but few nutrients. Use bonemeal or blood fish and bone at the same time to act as a slow release fertilizer. Not very environmentally friendly apparently, though opinions are divided.

Where to get it  

    Garden centers / DIY stores etc. last year's grow bags, or even new this years.

Pea shingle

What's it like? - Pea shingle is sometimes called 10mm stone, it's fairly fine gravel. It is sometimes suggested that you can add sand to poorly drained soil, but this can actually make poorly drained soil worse, as its very small grains can block existing drainage channels.

Where to get it

    Builders merchants and plant hire companies. In bulk 0.5 - 1 ton is the cheapest way, share with neighbors if you don't need much.

    Usually from the same source in bags. Don't get it from the garden centre - very expensive.

Others - Spent mushroom compost, composted paper waste, composted bark, spent hops from breweries, seaweed etc.

Depending on where you live, these or others may be available cheaply or for free. The main criteria is always that the conditioner should be crumbly, not smelly and with no or few recognizable raw materials. If you can get it in the raw state, e.g. seaweed, then compost it down first as any other organic matter before using on the garden.

Take care though when using any of these, don't use them initially as freely as you might the tried and trusted conditioners. Mushroom compost for instance often has very high levels of lime, so your acid lovers will hate it. Try a small amount in a restricted area first before you order in a truck full.

Personally, I have used composted bark and coir (coconut fibres). I have found both to be reasonable soil conditioners if not always really well rotted enough out of the bag. If using these use a concentrated fertilizer as with peat.

The key thing about bulk organic material is the word BULK, use lots of it! An averagely poor soil in a garden of medium size can swallow a ton without much difficulty, so don't worry too much about over-ordering, use lots of it!