Use Wetting Agents to Help Water Management

No matter how well your irrigation program is set up, the sides of the plant beds always dry out faster than you want.

March 16, 2022
3 mins

No doubt you have seen it happen in your nursery, along the edges of plant beds or the sides of tunnels. You’ve measured moisture levels in the center of the beds and they’re looking fine. But no matter how well your irrigation program is set up, the sides of the plant beds always dry out faster than you want. You are facing the challenge of re-wetting growing media with precious water you can ill afford to waste. Especially when switching from peat-based to peat-reduced or peat-free growing media, you may need to completely change your water management.

The challenge with dried-out substrates 

Substrate can become water-repellent, or hydrophobic, if it has been left to dry out during several irrigation cycles. Once a growing medium becomes water-repellent, it can be very difficult to get moisture levels in the pots and containers back up to an optimum: water will no longer easily infiltrate the substrate, leading to runoff and loss of (water-soluble) feed. 

Water-repellency can become most apparent in peat-reduced and peat-free components of growing media. These new growing media often have a much lower water-holding capacity. You may need to water more frequently or use more each time. 

Specific areas on the nursery field run the highest risk of developing water-repellency, hydrophobicity: the edges of plant beds, plants in the air flow from ventilation windows in greenhouses, plants getting direct sunlight, or in dry east winds. 

Ideally, water levels in pots and containers should be kept constant, and that’s where it gets tricky: watering is something most growers have to do “by feel.” In many cases, the center of a plant bed is used to determine whether the block needs to be watered. If the plants in the center are wet enough, then that block of plants will not get a full round of irrigation. 

Unfortunately, by the time the plants in the center of the beds start to dry out, the plants along the edges will already have been dry for a while. Watering more frequently by hand can become necessary to keep the edges sufficiently moist and in good condition. 

The importance of water 

Water could be considered as the plant’s most essential mineral. Water plays a key role in

  • evaporation and transpiration, as it helps to cool down leaf temperature 
  • building strong stems and leaves 
  • the transport and uptake of nutrients 

Without water, there can be no growth. So, it is our job to create efficient nutrient transport. 

The role of wetting agents in dried-out pots and containers 

Wetting agents can play an important role in several challenging nursery situations. 

In spring it can help to kick-start early spring hardy nursery stock and herbaceous growth through aiding the initial wetting of plugs. Generally grown as dry as possible through the winter, at first watering it can take several attempts to get plugs sufficiently wet to apply liquid feed. This can be overcome by adding a wetting agent that quickly infiltrates the plugs. 

If about 10–15% of a plant bed consists of edges, that’s 10–15% of pots that are prone to dry out very quickly. That same 10–15% will then likely have issues with growth and difficulty taking up nutrients. Applying a wetting agent ensures that water can evenly spread throughout the pots and containers, infiltrating even into water-repellent growing media, making sure the whole pot becomes wet. Pots will stay sufficiently wet for longer, especially the ones along the edges, requiring less frequent watering and reducing the amount of water you need to supply. A wetting agent can really help to save on labor and watering costs. 

Another role is improving shelf life by maintaining pot and container quality, both along the supply chain and in the final position at the end-consumer in the garden. When applied prior to dispatch, the wetting agent will ensure the pots and containers become wet quickly for the end user and will make the most of any rainfall or limited irrigation.  

If you are looking to improve your water management and reduce watering man hours, incorporating a wetting agent into your substrate or adding it to your irrigation water could be your solution. 

Read more about H2Gro and its application!