Irrigation Tips

Water Smarter
Water is probably the single most important resource required to grow a plant, and by optimizing your irritation techniques and working with Mother Nature you can have productive plants with minimized waste. Summer’s heat, long days and the resulting vigorous plant growth all add up to the most challenging time of year for managing your irrigation. We’ve got some good tips to help you stretch your water while still maintaining healthy plants.

First and foremost, keeping your plants robust and in good condition will go a very long way to making the best use of your irrigation efforts. A strong plant will have the resilience to handle natural fluctuations in water availability, temperature and other conditions. Take a look at the soil you’re working with, too. Both clay and sandy soil can be easily improved by incorporating organic matter (compost) and thus provide enhanced water permeation/retention qualities. Supplemental compost will lighten clay and add vital organic matter to fast-draining sandy soil.

 
Bare ground? Cover it up!
Mother Nature hates bare ground; that’s a truth that gardeners deal with every day. Rather than fight that reality, we recommend covering up any bare soil. A layer of mulch can go a long way to protect plants in the garden or landscape by insulating the soil, suppressing weed growth, adding organic matter to the ground, and holding in moisture. An even layer of topdressing can make a planting look tailored and uniform, too.

A layer of well-aged wood chips keeps the roots of a hydrangea cool and moist in this part-sun landscape.

If mulch isn’t your style, a groundcover crop will provide similar benefits and potentially more. At first glance, adding a groundcover or cover crop may seem counterintuitive for moisture conservation, but these plants will shade the soil and recycle moisture. The amount of water a cover crop will use is still less than the amount that can evaporate from bare soil, so a live groundcover is a great choice for locking in moisture to the environment. In the veggie garden, a low-growing cover crop such as New Zealand White Clover will produce a lush, green carpet that works hard providing all the earlier referenced benefits and fixes nitrogen in the soil to feed the neighboring crops.

A dense carpet of New Zealand White Clover cover crop between rows of veggie crops will keep weeds at bay, recycle moisture, and fix nitrogen in the ground. It's easy to grow and tolerates foot traffic.

In the landscape, an underplanting of ground-hugging perennial plants such as thyme, Corsican mint, Pachysandra, sedum/sempervivum (just to name a few) will not only provide the benefits of mulch, but they’ll also serve as a living backdrop for the other plants in the landscape. Add to that the evergreen quality of a groundcover, and you’ll have a vibrant, solid plant cover all year-round even in winter when herbaceous perennials and bulbs have retreated.

Soleirolia soleirolii (Baby Tears) serves as a very easy-care groundcover for a protected, semi-shade spot. This borderline hardy plant has persisted for more than a decade in this zone 8 landscape.

Creeping Thyme forms a fragrant, evergreen cover around a sunny planting. A light layer of mulch on the bare ground between the spreading plants will keep the weeds down and moisture trapped while the thyme fills in.

Galium odoratum (Sweet Woodruff) works as a wonderful underplanting for a deep shade planting.

Efficient Irrigation—Water the soil not the plants
Plants absorb moisture mostly through their roots, so it stands to reason that getting water directly to the rootzone is efficient irrigation. Whether you’re hand watering with a hose, watering can, or using an automated irrigation system, putting the water on/in the ground will get it to the plants faster than applying it to the foliage. Make sure you’re dispensing the water slowly enough for the ground to absorb it, otherwise the water will run off the soil surface to dissipate elsewhere. Slow, deep, infrequent irrigation is much better for plants, encouraging deeper root growth and hence, enhancing strong drought resistance.

Slow and steady is the way to go. Water individual plants slowly and deeply to encourage deep roots, healthy plants, and good drought resistance.

Sprinklers that disperse water in small droplets through the air might look cool, but a lot of valuable moisture is lost to evaporation in the warm, summer air. Wetting foliage can also promote foliar disease in plants.

Don’t be tempted to use sprinklers that disperse the water in the air. If you are looking for a show, impulse, rotary, and oscillating sprinklers are fun, but they tend to squander water and can lead to foliar disease. These methods will result in moisture loss due to evaporation and can also encourage fungal disease in plants by exposing the foliage to water.

If you do set up an irrigation system, consider drip irrigation. You can design it to target very specific plants/regions and get that slow, deep water penetration we discussed earlier.

Drip irrigation in row crops. A perforated 'tape' of flattened water conduit allows a slow emission of water directly onto the soil surface. The water penetrates the ground right where the crops are growing.

Drip irrigation in row crops. A perforated 'tape' of flattened water conduit allows a slow emission of water directly onto the soil surface. The water penetrates the ground right where the crops are growing.

Ollas: Ancient Watering Wisdom
An olla is a semi-porous container that is buried in the soil with just its opening above the surface. The container is then filled with water that gradually seeps out into the surrounding soil and directly to the roots of plants in the vicinity. This technique has been traced back thousands of years and is one of the most efficient for arid regions. As the plants use the moisture in the soil, the water in the olla is drawn through its walls and into the soil. Ollas simplify the watering process and require occasional re-filling (frequency depends on weather conditions, soil consistency and plant density). They eliminate runoff, evaporation (especially when the opening is capped), and don’t encourage weed growth.

A partially unearthed olla. Note how the surface of the olla is seeping moisture from the inside. When the entire container is submerged with only the neck exposed, the moisture in the olla will provide irrigation to plants with roots in the vicinity.

In times of increasing global temperatures, weather extremes and climatic uncertainty, conserving resources is a crucial consideration for successful gardening and growing concern. We hope these tips have given you some ideas for utilizing your irrigation water wisely in your plantings.

 Author: Kat B.