The Tuscan garden that holds onto rain
Borgo Pignano runs broad, shallow channels across its fields so rain has time to sink into the soil.
Borgo Pignano sits above Volterra on a 750-acre organic estate, with an 18th-century villa at its centre. Local stonemasons restored the buildings with traditional materials, and much of what reaches the kitchen comes from the farm or nearby producers. There is more on that approach in the Food area.
The estate collects rainwater for its gardens and irrigation. Across the fields, swales slow that water long enough to soak into the soil. Borgo Pignano says it was the first estate to introduce them in Tuscany.
Wait for the rain
A swale is a broad, shallow channel that follows a level line across a slope. It catches water on the way down and gives it time to soak into the ground. To choose the right place, wait for a proper downpour and watch where the water comes into the garden and where it gathers.
When the ground is dry again, mark the line with a spirit level on a long board. A water level or an A-frame level works too. Dig along that line, broad and shallow. Put the loose soil on the downhill side and shape it into a low mound, then plant it. Any overflow needs a clear route away from buildings and neighbouring land.
Check for buried services before you start. Bring in someone who understands drainage if the slope is steep, the ground is unstable or the soil drains badly. Mistakes near a building get expensive quickly.
For a flat or very small garden, a water butt is simpler. It saves rain for pots and beds without changing how water moves through the ground. More ways to work with water at home are in the Hearth.
Rainwater is naturally soft and low in minerals, which suits most garden plants.
Stored rain is my first choice in a garden. Indoors, find out what is in the tap water before choosing a filter. Water is the first thing to check in a room.
| What it is | A broad, shallow channel that slows runoff and gives it time to soak into the soil. |
|---|---|
| Where it goes | Across a gentle slope where runoff can reach it. Watch the garden during heavy rain before choosing the spot. |
| The line | Mark a level contour with a spirit level on a long board, a water level or an A-frame level. |
| The size | This depends on the slope, soil, amount of runoff and the heaviest rain it needs to handle. |
| The berm | Shape the dug soil into a low, broad mound on the downhill side and plant it to help hold the soil. |
| What to plant | Choose deep-rooted perennials, shrubs or trees suited to the soil and climate. |
| The overflow | Give excess water a safe route away from buildings and neighbouring land. |
| A flat garden | Use a water butt to store roof rain for pots and beds. |
The short answers
Quick answers for planning a garden swale.
What is a swale?
A swale is a broad, shallow channel that follows the contour of a slope. It slows rain running downhill, spreads it across the ground and gives it time to soak into the soil.
How do you find where a swale should go?
Watch the garden during heavy rain to see where runoff enters and where it gathers. Use that information to choose the area, then mark the exact contour with a spirit level on a long board, a water level or an A-frame level.
Should a swale be level?
Keep a contour swale level along its length so water spreads and soaks in. A spirit level on a long straight board, a water level or an A-frame level will help you mark the line. Swales designed to carry runoff use a gentle fall and need a different plan.
How deep should a garden swale be?
The depth depends on the slope, soil, amount of runoff and the heaviest rain it needs to handle. Keep a small garden swale broad and shallow. Larger earthworks need professional advice.
What do you do with the soil you dig out?
Shape it into a low, broad mound on the downhill side. This is called a berm. Planting it helps hold the soil in place.
What do you plant on a swale?
Plant the berm with species suited to your soil and climate. Deep-rooted perennials, shrubs and trees can use the moisture held below them while their roots help steady the soil.
Where is a swale a bad idea?
Leave steep or unstable ground, poorly draining soil and sites near foundations, wells, septic systems or underground services to a drainage professional. Every swale also needs a safe route for overflow during heavy rain.
What can you use in a small or flat garden?
A water butt is usually the simpler choice. It catches rain from a roof and stores it for pots and beds without changing how water moves through the ground. What size to get and what to do with it in frost is in the hotel that runs on rain.
Is rainwater better for plants than tap water?
Rainwater is naturally soft and low in minerals, so it suits most garden plants. It is especially useful for plants that dislike hard, alkaline water. A garden watered from a mountain stream by gravity is in the garden that came before the guest rooms.
Can you drink rainwater caught off a roof?
Use water from an ordinary garden butt on the garden. Roof runoff can pick up dirt and other contaminants, so drinking water needs suitable collection, treatment and testing under local rules.
The property. Borgo Pignano, above Volterra, Tuscany. Its sustainability page describes the restoration, local stonemasons and food sourcing. Its sustainability manifesto covers the swales and the claim that they were the first in Tuscany. The 750-acre organic estate is reported by Citizen Femme.
The guidance. The Royal Horticultural Society guide to swales covers siting, slope, soil, overflow and planting. Its rainwater guide explains why naturally soft rainwater suits most garden plants. Virginia Tech covers buildings, buried services and unsuitable ground. The CDC rainwater guide covers testing and treatment when rainwater will be used for drinking.
Reuse. Quote any part of this page with a link back to it. Educational purposes only, and not a substitute for medical advice.