Healthy plant roots need both water and air. In wicking beds, water rises from a reservoir into the soil, but if the soil becomes too wet, roots can suffocate and the bed can become smelly or unhealthy. This article explains why good aeration — the movement of air through the soil — is essential for plant health, how wicking beds can be managed to avoid saturation, and practical techniques such as drainage, deep cycling, soil biology, compost burial and plant selection to improve airflow and keep soil healthy.
Introduction — Why Aeration Matters
Plants cannot grow well in soil that is completely saturated with water because their roots need oxygen to function. Roots absorb nutrients and water from the soil, but they also release gases like ethylene, which needs to escape into the surrounding air. If the soil stays too wet, the space that should be filled with air becomes filled with water, choking roots and slowing growth. This is one of the main reasons some wicking beds fail — the soil becomes too wet and the roots cannot breathe.
Problem: Too Much Moisture in Wicking Beds
Many people report wicking beds that turn “putrid” or develop unpleasant odours. Often this happens because the soil near the base stays saturated for long periods. In some designs, water is applied from the top, and old water stays trapped below. This can create anaerobic (oxygen-free) conditions that harm plants.
To avoid this, it helps to understand how water and air move through soil. Water that enters from the top can push air out of place, and if the soil stays wet for too long, beneficial soil organisms like fungi and worms cannot thrive.
Technique 1 — Controlled Drainage
One simple method to improve aeration is to include a drain hole. This allows water that is no longer needed to escape freely, rather than remaining trapped. By supplying fresh water from below through pipes and allowing old water to exit through a drain, you can create a “first in, first out” water exchange system. This ensures that water in the reservoir does not stagnate and that roots have access to oxygenated soil rather than old, stale water.
Technique 2 — Deep Cycle Moisture Refill
Another useful approach is what the author calls a “deep cycle” refill. When the water reservoir is filled, it pushes out old air and water. As plants use that water, they naturally draw in fresh air around the root zones. This creates a cycle in which moisture is replaced and air is drawn back into the soil as water levels fall — mimicking a more natural wet-dry cycle that encourages plant health and prevents waterlogging.
Technique 3 — Soil Biology Creates Air Channels
Soil organisms such as worms and fungi play a major role in creating pathways for air and water. Worms burrow through the soil, leaving tunnels that allow air to penetrate deeply. Fungi produce filaments that help bind soil particles into stable clumps, improving structure and aeration. Encouraging soil biology through compost, organic matter and minimal disturbance creates a living soil with many microscopic and macroscopic pores that benefit both roots and microbes.
Technique 4 — Bury Compost for Local Aeration
Burying compost directly in the bed can help. Some gardeners use a compost bin with holes buried in the soil, or simply dig fresh compost into specific areas. These pockets of decomposing organic matter attract soil life and create local air pathways without disturbing the rest of the soil. This approach improves aeration while preserving the existing soil biology, which can be easily harmed by extensive digging.
Technique 5 — Avoid Barriers That Restrict Roots
Barriers like cloth or liners that restrict where roots can grow can also restrict airflow. Roots that spread throughout the soil help reduce stagnant water because they draw moisture and facilitate gas exchange. For shallow-rooted plants, combining them with deeper-rooted species — such as Senna alata — can help “draw down” excess water and improve aeration by creating more root channels throughout the soil profile.
Technique 6 — Emergency Aeration with a Garden Fork
If a soil becomes compacted or waterlogged, a simple intervention is to insert a garden fork into the soil and tilt it slightly to fracture the soil. This creates new air channels and temporarily improves oxygen flow to roots. This method is useful when beds become too dense or when roots struggle to access fresh air.
Balancing Water and Air
The key balance in wicking beds is water and air. Too much water without avenues for air exchange will limit root respiration and plant growth. By adopting techniques that allow both air and water to move freely through the soil, gardeners can maintain healthy, well-aerated soils. A combination of proper drainage, deep cycling, strong soil biology, and plant selection helps maintain this balance, resulting in healthier, more productive plants.
Summary
Healthy wicking beds are not just about water supply; they must also provide enough air for roots and soil organisms. Saturated soil blocks oxygen, slows growth, and can lead to unpleasant conditions. Practical techniques — such as providing drains, managing water cycles, encouraging worms and fungi, burying compost, avoiding barriers, and creating air channels — all improve aeration. Taken together, these practices ensure that wicking beds function effectively by supplying both moisture and oxygen to plant roots, leading to stronger, more resilient plants.
