Over the past couple of months, there has been virtually no rain. Despite a wet summer, the soil moisture reservoir has dwindled. After experiencing the joy of overflowing water tanks, robust and healthy plant growth, and luxury levels of soil moisture, watering techniques have again become a top priority.

Last year, we endured many long months of drought. The view of our garden was so sad. The grass was crisp or died; brown was the new green. The lush green valley below is again on the turn. It’s been a dry winter. Just as plants burst into bud and new growth in early spring, they desperately need water to thrive. Since we are on tank water, every drop is precious and used intentionally. Once again, I’m watching the water trucks delivering this much-needed resource to many gardeners relying on rainwater rather than town supply.

During the drought, we lost two mature mandarin trees. It was heartbreaking. I learned hard lessons from taking tree survival for granted. Even the perennials and many established trees hung on for dear life. I assumed they were resilient enough to withstand the harsh conditions with limited water and heavy mulch. It pained me to realise I needed to shift my thinking and strategies, or I could lose more trees.

Abiotic Stresses

As they say, ‘no pain, no gain’! I realised that my plants were experiencing the harmful effects of multiple abiotic stresses. Fires were everywhere. Cloudy conditions and heavy smoke reduce photosynthesis, resulting in poor sugar development due to lack of sunlight. Many plants became weakened. The ongoing drought contributed to low soil moisture levels. High-temperature stress causes an increase in transpiration and damage to plant cells. Heatwaves went on for days. The conditions were hot, dry and windy. Strong winds have an impact on moisture loss through leaf stomata. Wind stress can cause higher transpiration and plant dehydration. While we have some windbreaks for crop protection, other garden zones are still exposed to gusty winds as we are high on a hill. These abiotic stresses are often precursors to biotic stresses like pests, pathogens and weed competition. A domino effect! So, I stopped planting for the first time in years. It was a time for deep reflection to rethink my strategies and mitigate these issues.

With challenging climate abnormalities in so many locations, gardeners need a variety of techniques in their toolkits to help plants survive and thrive. I’m optimising plant health by working on the soil’s moisture-holding capacity, supplementing nutrition, and using diverse irrigation methods.

Techniques to Improve Water Retention

Soils and potting mixes are like giant sponges. Our growing media is one of the factors determining how water infiltrates and is stored in soil pores. Garden soils are diverse, with combinations of clay, loam and sand with different moisture-holding capacities. I have a predominance of clay soil that tends to hold moisture well so long as it’s covered with mulch. Adding bentonite clay can improve water retention in very sandy soils. It can also help improve water absorption on water-repellent soils. As a bonus, bentonite clay provides soluble plant nutrients like calcium, magnesium and potassium.

I also grow many plants in containers using homemade potting mix. Most commercial potting mixes are based on pine bark, which quickly becomes hydrophobic. To avoid this, I include coir peat, compost, vermiculite, and worm castings. These ingredients retain water and help buffer plant stress.

Rehydrated coir peat or coconut fiber is hydrophilic and re-wets easily. Some forms of coir can hold water up to 8-9 times its dry weight, making it a valuable input for retaining soil moisture.

Vermiculite can absorb 3-4 times its weight in water due to a strong capillary action. The particles hold water, gradually discharging moisture.

Due to its durability, I can justify the investment.

The worm farms I use provide a rich source of Vermicast that helps regulate soil moisture and lessen drought-induced plant stress. Worm castings store 2-3 times more moisture than their weight and help water infiltrate through the potting mix and soil.

Likewise, compost is another input that holds moisture like a sponge, buffering abiotic stresses. As a result, my container-grown plants survive a lot longer between watering.

I also add organic matter like mulch, aged manures and kitchen scraps to enhance soil structure. These inputs add bioavailable nutrients and increase the soil’s moisture-holding capacity.

Watering Techniques to Enhance Plant Nutrition

While plants have many adaptive defence systems to survive changing environmental conditions, they can use a helping hand. I give my food crops priority with more regular applications of water enriched with nutrients. I make the watering count! I also use every opportunity to liquid fertilize.

Soil drenching is one technique I use for potted plants. I add liquid nutrients like seaweed, fish emulsion or vermicast leachate to a large tub, then submerge the pots to rehydrate them until bubbles appear. My indoor plants have a weekly ‘day spa’ treatment; the outdoor container plants get one monthly. Soil drenching rehydrates potting mix with trace elements that slowly release between treatments. The plants perk up considerably as a result.

Foliar spraying is an easy way to manage nutrient deficiencies in plants with drought-related water stress. It’s also a protective strategy in hot weather. This efficient nutrient delivery technique replenishes macro and micronutrients via the leaf stomata. I spray early in the morning and find that foliar nutrition helps minimize the negative impacts of drought stress, such as lower yields and poor growth.

Liquid fertilizers, vermicast and compost teas are also in my toolkit. I vary the soluble nutrition I apply to plants depending on what they need or what I have available. Biostimulants like seaweed, aloe vera and fish emulsion help enhance plant defences and mitigate water stress. The kelp and fish products are available in powdered or liquid forms and are easy to apply to the root zone or via foliar sprays. I make liquid aloe vera plant extracts and use them similarly.

Aerated teas made from worm castings and compost also provide plants with water, nutrients, and biology to build plant health. Some of my favourite liquid plant extract fertilisers are made from stinging nettles and comfrey. The leaves are rich in minerals, and although they can be stinky after soaking in water, plants respond quickly to the bioavailable nutrients.

Fertigation or irrigating with fertilizer is an opportunity for many gardeners. Nutrients can be added to rainwater collected in tanks, barrels and buckets. One of my clients installed a mini 1000L water tank for her suburban garden. She connected the irrigation pipe so she could use the tap system to selectively water the garden beds as needed. I suggested Su use this dedicated tank to liquid fertilise simultaneously.  All she had to do was add liquid seaweed and other biostimulants to the tank water. This saved Su time and effort in mixing liquid fertilisers in watering cans. She was thrilled to have her tank perform double duty. We also fertigate several garden zones with 40-gallon tubs with taps. I add the nutrients to the rainwater and use watering cans to apply to the soil. Another benefit is that these fertilizers are not contaminated with chlorine, fluoride, or other chemicals from municipal water.

Waste not, want not! Lastly, cooking water, spent flower vase water, fish tanks, ponds, bird baths, and pet water bowls are examples of nutrient-enriched water sources. Watering plants with ‘waste’ water is a way to add bioavailable minerals into the soil. We use buckets to capture shower or bath water and apply this to perennials in rotation as needed. These free liquid resources enhance sustainable gardening while building plant health.

By following various watering techniques to retain moisture and enhance plant nutrition, our plants will be healthier, more tolerant to stresses and likely to thrive rather than just survive.