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Some early summer weather is coming at us hot, bringing potentially record breaking temperatures to the Pacific Northwest at a time of year when the sun’s angle is at its highest and it seems shade is nowhere to be found. These extreme weather events can be extremely stressful to those of us trying to keep plants growing when it hits the triple digits, but proper watering you can help your plants make it through this next heat wave.
Water is essential to help transport nutrients, support homeostasis and support photosynthesis. Though all plants differ in their watering needs, some requiring constantly saturated soils, and others like the cacti in the Atacama Desert surviving on nothing but fog rolling in, each plant must have the adequate amount of water in order to continue actively growing, or at the very least, surviving.
When plants are not receiving enough water they can slow growth or show stress. Plants contain small openings located on the outer layer of the surface of their leaves and stems called stomata which regulates gas exchange and transpiration. Stomata will typically close when they are not receiving enough moisture in the heat to help conserve water, however this also restricts photosynthesis along with cooling through transpiration. If water continues to be restricted, the plants will then begin to shut down all together which can be witnessed through wilting foliage or discoloration.
If you’re living in the drier areas of the West, it’s important to continue watering your plants throughout the beginning of our dry season and there are still steps you can take to help your plants survive and thrive.
Be sure to check out our tips below for more guidance on keeping your plants well watered while also building deep, resilient root systems in your garden.
1. Water deep and infrequently – Besides a handful of plants like the giant Gunnera’s, or various wetland species, most of the plants that we grow in ground will benefit from deep waterings once a week that thoroughly soak the soil, both on the surface but also deep down in the soil layers. Watering in this way will encourage the roots to grow deeper and seek out moisture in the lower soil horizons, making for a more resilient and deep rooted tree in the long term. Want to go on vacation this year and not worry about your trees dying? Then give them deep waterings! Or install an automatic drip irrigation system.
2. Water the whole root zone – The biggest downfall of drip irrigation systems with single emitters per plant is they often only water one small area. Root systems don’t just grow down; they grow far and wide, so watering in a way that encourages both lateral as well as deep root growth will make for a healthy root system. Using drip tape spaced at 12″ apart is a great way to accomplish this. And, if you’re planting climate appropriate plants that won’t need supplemental water after establishment, you can reuse that drip line on your new plantings and get the most out of all that plastic.
3. Water at the right time of day – Making sure your plants are watered before they need it is the best way to ensure they don’t suffer a hydro deficit. Be sure to water days before the heat wave arrives, as opposed to once it’s here and your plant is already showing stress. Also, the time of day you water can be very important. Ideally if you can water before sunrise, or as early in the morning as possible, your plants will have time to fully uptake that water before the photosynthesis factory really starts cranking for the day.
4. Plant with hydro zones in mind – We’ve been guilty of it many times, even though we theoretically know better, but planting plants with similar water needs is the easiest way to ensure that they are all thriving for the long term. As tempting as it can be for various reasons to combine plants with different water needs, you will likely only end up with one of them surviving in the long term. Keep the mediterranean garden dry in summer, the cactus dry in winter, and keep the apple orchard watered all summer. Doing a little bit of research into a plant’s water needs and grouping them accordingly can save you a lot of headaches.
5. Listen to your plants and listen to your intuition – If a plant is really struggling, don’t be afraid to move it into the shade or give it extra water. Even newly establishing drought tolerant plants need supplemental water to get established. If you’re paying attention to how the plant is looking and what the conditions are then you should be able to keep almost any plant alive, even through the most extreme heat waves.