Soil, practical guide
Improving garden soil.
Why soil structure matters before you plant, how to work out what you have, and what to do about clay, sand and tired ground.
- Test firstSqueeze it
- AddOrganic matter
- Soil ImproverA trowelful, worked in
Three tests you can do at home
Ten minutes with a trowel tells you more than any guess.
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The squeeze test
Squeeze a handful of moist soil. Sandy soil feels gritty and will not roll into a sausage. Clay feels sticky, rolls into a long thin sausage and takes a shine when rubbed. Silt feels soapy. Loam sits in between.
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The jar test
Fill a straight-sided jar about a third with sieved soil, top up with water, shake and leave it to settle. Sand drops first, then silt, with clay on top. The layers show roughly how much of each you have.
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The drainage test
Dig a pit about 60 cm deep, fill it with water, cover it and leave it for 24 hours. If water is still there afterwards, the drainage is poor and it is worth improving before you plant.
What kind of soil is it?
The RHS describes six soil types. These are the five most gardens are made of.
Clay: heavy, fertile, slow
Clay holds nutrients well but drains slowly, so it is cold and wet in winter and bakes hard in summer. Organic matter breaks up the cloddy structure, so the soil is easier to work, warms up sooner and compacts less.
- FeelsSticky, smears, rolls into a long sausage
- AddOrganic matter, worked in or as a mulch
- DigIn autumn, when it is not claggy, so frost breaks it down
- Sand or gritNot a practical fix, so skip it
Sandy: light, quick and hungry
Sandy soil drains fast and warms quickly, but it is low in nutrients and often acidic. Organic matter helps it hold water and nutrients. It may still need feeding.
- FeelsGritty, falls through the fingers
- AddOrganic matter, often and generously
- DigIn spring
- Watch forDrying out, and nutrients washing away
Silty: fertile but easily squashed
Silt holds moisture and is fertile, but it compacts easily. Organic matter binds the particles together and reduces compaction. Try not to walk on it when wet.
- FeelsSoapy, does not clump
- AddOrganic matter
- Watch forCompaction and a crust on top
Chalky: alkaline and often shallow
Chalky soil is very alkaline, often shallow and low in fertility. Organic matter rots down quickly here, so top it up regularly. Chalky soil is very hard to acidify, so choose plants that tolerate lime.
- TestA pinch that fizzes in vinegar contains free chalk
- AddOrganic matter, and top it up often
- PlantsChoose lime-tolerant ones
Loam: the balanced one
Loam is a balanced mix of sand, silt and clay, and the easiest soil to garden. It still benefits from regular organic matter, which keeps its structure and feeds the soil life.
- FeelsBetween gritty and sticky
- AddOrganic matter, regularly
Organic matter, and how much
Organic matter binds soil particles into crumbs that roots can push through, holds water and nutrients, and feeds plants as it rots. Compost, well-rotted manure, leafmould and a soil improver all do this job.
For digging in, the RHS gives a typical range of about 5 to 10 kg per square metre, roughly half to one 15-litre bucket. As a mulch on the surface, spread at least 5 cm and ideally 7.5 to 8 cm, leaving a 10 cm gap around woody stems. There is no single best month: the RHS gives late winter to spring for mulching, spring for digging in, and autumn too, except on sandy soil. Pick a day when the soil is moist and neither frozen nor waterlogged.
Sand and grit will not fix clay
The RHS reckons it would take about 250 kg of grit per square metre to halve the clay in a very clayey soil, and it can leave the soil less stable. Organic matter, raised beds and suitable plants work better.
Three jobs that get mixed up
They are not the same thing, and most gardens use all three at different times.
| What is being compared | Soil improverworks on the soil | Mulcha layer on top | Plant feedworks on the plant |
|---|---|---|---|
| What it does | Improves soil structure, drainage and how well soil holds water and nutrients, over time. | Covers the soil, holds moisture in and keeps weeds down, and adds organic matter as it rots. | Supplies nutrients to a plant that is growing, this season. |
| When | Before planting, or between seasons. | On moist soil, not frozen or waterlogged. Avoid late summer. | While a plant is actively growing. |
| How | Worked into the top layer of soil. | Spread on the surface, at least 5 cm thick. | Watered in, or applied as the label says. |
| Examples | Compost, well-rotted manure, leafmould, Soil Improver. | Compost, leafmould, bark. | Tend, Bloom, Beanstalk and Green. |
General definitions in line with the RHS. Compost can be either a soil improver or a mulch, depending on how you use it.
You need less digging than you think
The RHS says only minimum cultivation is needed. Clay is best dug in autumn when it is not claggy, so frost can break it down. Light, sandy soil is best dug in spring. Double digging is rarely necessary.
No-dig means spreading organic matter on the surface and leaving soil life to work it in. The RHS lists less labour, fewer weeds, less watering and more worm activity. To start a no-dig bed it suggests 10 to 15 cm of organic matter, then about 5 cm a year to keep it going.
Signs your soil needs improving
If you nod at two or more of these, improve the soil before you plant.
- It compacts easily underfoot, or forms a hard crust when dry
- It drains poorly, or stays waterlogged after rain
- It cracks visibly in dry weather
- Plants establish slowly, or look pale soon after planting
Where Soil Improver fits
Soil Improver is made on our family farm in Cumbria from what the farm's renewable energy process leaves behind. It is a soil improver, not a plant feed: it prepares the ground, and it does its best work worked into the top layer of soil rather than left on the surface.
It comes in a 1L pouch for pots, planting holes and small patches, and a 17L tub for more. For a big new border you will probably want a bulk supplier alongside it.
Soil Improver: For Beds, Borders and Pots
A peat-free soil improver for working into beds, borders and pots before you plant. It is not a plant food.
- How to useWork a trowelful through the top layer of soil around a plant or two. Potting up? Mix a couple of generous handfuls into the compost.
- Size1L pouch, also a 17L tub
- Also good to know100% natural, peat-free and made without synthetic chemicals.
Questions people ask
When should I use Soil Improver?
Before planting, or between seasons in beds and borders that need a refresh, rather than on an established, actively growing plant.
Do I still need a separate plant feed?
Soil Improver prepares the ground. Once something is actively growing, a dedicated feed such as Tend, Bloom, Beanstalk or Green covers the growing stage.
Can I use Soil Improver in containers and pots?
Yes, generally. Its job, preparing the growing medium before planting, applies to pots as well as open beds. Potting up? Mix a couple of generous handfuls into the compost.
Is this a bulk soil delivery, like a bag from a builders' merchant?
No. Soil Improver comes in a 1L pouch, and a 17L tub, for beds, pots and borders. For a large new border you will likely want a bulk supplier as well.
Is it good for roses?
Yes. Preparing the soil around roses before planting, or refreshing it between seasons, is exactly the kind of job Soil Improver is built for.
Is Soil Improver peat-free?
Yes, like the rest of the range.
