Water – for the health of your garden

Keep your garden hydrated this summer with the right irrigation

As the warmer summer weather arrives, we’re reminded to keep hydrated on those hot sunny days. But it’s not just you who needs to drink plenty of H20; your garden needs it too! My last blog talked about the importance of mulching and the role it plays in retaining soil moisture. I want to follow on from this with some information on the importance of irrigating your gardens to maintain plant health.

Why is irrigation important?
We all know we should water our garden, but why? Ground water absorbed by the roots of your plants plays important roles in the uptake and transport of soil nutrients throughout the plant, keeping plant cells hydrated so it can function and grow. 

Water can evaporate from the soil surface and plants also loose moisture through the surface of their leaves. Just like we can become dehydrated in hot weather, so too can your plants. Water loss from soil and plants increases during hot and windy weather and plants without enough water can wither and die. 

How much is enough water? 
While this is a simple enough question, the answer is anything but. 

Variables like plant type and location, soil texture, and weather conditions all influence how frequently and how much you should irrigate your garden. The moisture preference of individual plants is arguably the most important factor e.g. succulents require less water than say the herb basil. 

Plants in raised beds will often have greater irrigation needs than plants in open ground as they will drain more quickly and are more exposed to the drying effects of sun and wind. Light soils will need more regular irrigation than heavy soils as they drain more quickly also – think of the different drainage characteristics of sandy and loam soils. Small planter boxes have a smaller mass of soil to hold a reserve of water and will need more regular irrigation. Of course, plant need is the overriding consideration in each of these situations. 

A lot of the guess work around the frequency of irrigation with respect to location and soil texture can be removed by using a moisture meter to test soil moisture levels. These are inexpensive and available from many garden centres.

When to water your plants
While I prefer to irrigate my gardens in the evening to avoid the sun evaporating some of the soil moisture away, it is better to irrigate some plants like tomatoes in the morning. This is so the leaves and fruit can dry off quickly and minimise the potential for fungal spores to settle and attack the plant. 

When it comes to how much to irrigate: less frequent and heavy irrigation is better than more frequent and light irrigation. The reason for this is less frequent and heavy irrigation will soak the soil to a greater depth and as the surface soil begins to dry out plants are encouraged to send their roots deeper for remaining water. Deep rooted plants are less vulnerable to drying out during hot weather.

In contrast, frequent light irrigation will only supply water to the soil surface resulting in shallow root systems, making your plants more vulnerable during hot weather. Of course, some plants have naturally shallow root systems and will need more frequent watering.

Top tips to keep your plants hydrated
If the above seems a bit of a muddle following these simple rules of irrigation will help:
  • Know the moisture needs of your plants
  • Use a moisture meter
  • Understand the influences plant location and soil type have on irrigation
  • Give your plants a bit more water if the weather is hot and windy
  • Irrigate in the evenings but try to irrigate the soil around plants and not the foliage or fruit
  • Irrigate less frequently and more heavily
And don’t forget to mulch your garden!

For more information on efficient irrigation follow this link.