Key takeaways
- The checks take about an hour in total, spread over a few days to catch frost, wind and rain
- Full sun means 6 or more hours of direct sun, so photograph the garden at 9am, 1pm and 5pm
- Frost that lingers along a fence or in a dip marks a frost pocket, so keep tender plants out
- A jam jar of soil and water shows whether you have sandy, silty or clay soil within a day
- Test soil pH in three or four spots, as it can vary across a garden
- Mark it all on one sketch map, then choose plants to suit each spot
A garden audit is a quick look at your plot’s sun, soil, frost, wind and drainage before you buy any plants. It takes about an hour in total, spread over a few days so you catch a frosty morning, a breezy day and a wet one. The result is a simple map that shows what will grow where.
It’s especially useful in a new-build or newly moved-into garden, when you don’t yet know its quirks. Each check below takes 5-10 minutes, and there’s a full checklist at the end.
Why audit your garden before you buy plants?
Most plant failures come from the wrong plant in the wrong spot. Think of a sun-lover in four hours of light, an acid-lover in chalky soil or a tender shrub in a frost pocket. No amount of care fixes a plant that doesn’t suit its site.
An audit tells you what you’ve got, so you can choose plants that will thrive. Grab a pencil and draw a rough plan of the garden first. You’ll mark everything onto it as you go.
Which way does your garden face?
Aspect is the direction your garden faces, and it shapes everything else. Stand with your back to the house wall and check a phone compass. The direction you face is your garden’s aspect.
- South-facing: sun across most of the garden for most of the day.
- North-facing: the beds nearest the house sit in shadow, but the far end may get sun.
- East-facing: morning sun, afternoon shade.
- West-facing: afternoon and evening sun.
Draw a north arrow on your plan. Our guide to reading your garden’s aspect and light explains what each direction means for planting.
A rough sketch with a north arrow, sun path and shady areas is all you need to start your audit map.
How much sun does each part of the garden get?
Full sun means six or more hours of direct sun a day. The easiest way to check is to look three times on one clear day.
Photograph the whole garden from an upstairs window at 9am, 1pm and 5pm. Anywhere sunny in all three photos is likely full sun. Sunny in two is part shade, and one or none is shade. Shade the areas on your plan.
The winter sun is much lower than the summer sun, so shadows are far longer. If you can, repeat the photos in winter. Our sun mapping guide gives a more detailed hour-by-hour method.
Where do frost pockets form?
Cold air behaves like water. It flows downhill and pools behind anything solid, such as a fence, a hedge or a dip in the ground. Those cold spots are frost pockets, and they can damage tender plants and early blossom.
On the next frosty morning, walk round the garden once the sun is up. Note which patches stay white after the rest has thawed, and mark them on your plan. Keep tender plants out of those spots and choose tough, hardy ones instead.
For anything that has to live in a cold spot, our guide to protecting plants from frost explains fleece and other covers.
The strip of frost along the shady fence shows where cold air settles. Tender plants would struggle there.
Finding the windy spots
Wind speeds up through gaps, and new housing estates are full of them. The gap between two houses works like a funnel, so plants in its path get battered and dried out.
To find the windy spots, tie strips of light ribbon to a few bamboo canes. On a breezy day, push them in around the garden: one in the middle of the lawn, one in any gap between buildings and one at each exposed corner. Watch for ten minutes. Ribbons streaming flat show the windiest spots.
Solid fences don’t always help, as wind tumbles over the top and swirls down the other side. A windbreak with gaps, such as a hedge, slatted fence or mesh, slows the wind more gently. Our guide to plants and windbreaks for exposed gardens has more ideas.
A ribbon on a cane streaming flat shows a wind funnel between houses. Plants here need shelter or toughness.
The jam-jar soil test
The jam-jar test shows your soil’s mix of sand, silt and clay, for free. Dig some soil from about a spade’s depth down, not just the surface.
- Half-fill a straight-sided jar with soil.
- Top up with water, leaving a little space, and add a drop of washing-up liquid to help it separate.
- Put the lid on and shake hard for a minute.
- Leave it somewhere it won’t be disturbed.
Sand settles within a minute, silt within a couple of hours, and clay can take a day or more. Then look at the layers:
- Mostly sand: free-draining, dries out fast and needs plenty of organic matter.
- Lots of clay: sticky and wet in winter, cracks in summer, slow to warm up, but rich.
- A fairly even mix: loam, the soil most plants love.
Our guide to UK soil types helps turn the result into a plant list.
After settling, the layers show your soil’s make-up at a glance. A thick sandy layer means free-draining soil.
Checking your soil pH
pH tells you whether your soil is acid, neutral or alkaline. It matters most for plants like rhododendrons, camellias and blueberries, which need acid soil.
A cheap pH kit is all you need. Test a few spots, as the result can change from one end of the garden to the other.
A cheap test kit from a garden centre is fine. Test three or four spots separately, as pH can vary across one garden. Soil near house walls can be more alkaline where old mortar or rubble is buried. Our guide to soil testing and pH explains how to read the results.
Mapping wet and dry spots
The morning after heavy rain, walk the garden and mark three things on your plan: puddles, ground that squelches underfoot, and ground already drying out. Puddles that hang around for hours often point to compacted soil or heavy clay.
Puddles that linger for hours point to compacted soil or heavy clay. Mark them on your plan.
New-build gardens often have a thin layer of topsoil over squashed subsoil. Push a spade in where water lingers. If it hits a hard layer, breaking it up and adding organic matter will help.
Now combine your wet-and-dry map with your sun map. You’ll get four types of spot:
| Spot | Good plants |
|---|---|
| Damp shade | Ferns, hostas, astilbes |
| Damp sun | Moisture-loving perennials such as Siberian iris and persicaria |
| Dry shade | Tough ground cover such as epimedium and geranium macrorrhizum |
| Dry sun | Lavender, rosemary, thyme and silver-leaved plants |
Hunting for microclimates
Every garden has spots warmer, cooler, wetter or drier than the rest. These microclimates are worth finding.
A sunny house wall stays warmer than the open garden, which makes it a good home for a fig or other borderline plants.
- The base of a sunny house wall soaks up heat and stays warmer on cold nights. It’s the place for borderline-hardy plants, such as a fig.
- The strip right next to any wall is often in a rain shadow and stays dry. It suits drought-tolerant plants.
- Paved corners that trap still air can bake in summer.
- The foot of a north-facing fence stays cool and even, which suits woodland plants.
The garden audit checklist
Run through these eight checks and mark everything on one plan. Only the jam jar and the weather-dependent checks carry over to other days.
| Step | Check | How | Time |
|---|---|---|---|
| 1 | Aspect | Phone compass, back to the house | 5 min |
| 2 | Sun | Photos at 9am, 1pm and 5pm | 10 min |
| 3 | Frost pockets | Walk round on a frosty morning | 5 min |
| 4 | Wind | Ribbons on canes on a breezy day | 10 min |
| 5 | Soil texture | Jam-jar test, read the next day | 5 min |
| 6 | Soil pH | Test kit, three or four spots | 10 min |
| 7 | Wet and dry spots | Walk round after heavy rain | 10 min |
| 8 | Microclimates | Check walls, corners and fence bases | 5 min |
Kit: a phone, paper and pencil, a jam jar, a pH kit, a few canes and some ribbon.
Common garden audit mistakes
- Judging sun from one glance. A garden that looks sunny at noon may get only a few hours of direct sun. Take all three photos.
- Testing only the surface soil. Dig down a spade’s depth for the jam jar, and check for hard layers underneath.
- Assuming a solid fence means shelter. Wind can swirl down behind it. Use the ribbon test to see what really happens.
- Auditing once and forgetting it. Trees grow and neighbours build. Re-check the sun every year or two.
Frequently asked questions
What is a garden audit?
It’s a quick survey of your garden’s sun, soil, frost, wind and wet spots. You note which way the plot faces, where the sun falls, where cold air settles and what the soil is like. The result is a simple map that shows what will grow where.
How do I find out which way my garden faces?
Stand with your back to the house and check a phone compass. The direction you face is your garden’s aspect. South-facing gardens get the most sun, north-facing ones the least near the house, and east or west gardens get morning or afternoon sun.
How do I test my soil without buying a kit?
Use the jam-jar test to see how much sand, silt and clay you have. Half-fill a jar with soil, top up with water, shake hard and leave it to settle. Sand drops in a minute, silt in a couple of hours and clay can take a day.
Where do frost pockets form in a garden?
Frost pockets form where cold air collects, in dips and behind solid fences or hedges. Cold air flows downhill like water and pools against barriers. On a frosty morning, note which patches stay white after the rest of the garden has thawed.
When is the best time to do a garden audit?
Any time of year works, but check the sun in both summer and winter. The winter sun is much lower, so a bed in full June sun can be in shade in December. Frost checks need a cold, clear morning, usually between November and March.
Are cheap soil pH test kits accurate enough?
Yes, they’re fine for choosing plants. You only need to know whether your soil is acid, neutral or alkaline. Test three or four spots separately, as pH can vary across a garden, especially near walls where old mortar can make soil more alkaline.
With your audit done, our guide to designing a new-build garden shows how to turn your map into a plan, and the garden design hub has plenty more ideas.
Our team produces practical UK gardening guidance from source research, contributor records and established horticultural practice. Editorial standards are overseen by Matt W.
