Feeling really hot this summer? It’s right. Everywhere you go, you can see news about record high temperatures and wild fires. In such hot weather, how can plants in a garden survive and thrive? Record Temperature July 2018 is the hottest month in California since 1895, when the temperatures were first recorded. The average statewide temperature was 79.7 degrees, according to National Oceanographic and Atmospheric Administration. Several places in southern California set records for the hot temperature: UCLA: 111 Fahrenheit degrees; Burbank Airport 114; Santa Ana, 114; Riverside, 118; Ocotillo Wells (San Diego): 124. According to Indicators of Climate Change in California, a comprehensive study by the California Environmental Protection Agency,
- “Annual average air temperatures have increased since 1895, with the warmest four years on record occurring in the last four years.
- Five of the state’s years with severe to extreme drought since record keeping began in 1895 occurred between 2007 and 2016.
- Some of the largest glaciers in the Sierra Nevada have lost between 50 to 85 percent of their surface area since 1903.”
Wild Fire With the record high temperature, 2018 is another year with huge wild fires. According to the same study above: “The area burned by wildfires each year has been increasing since 1950. Five of the largest fire years have occurred since 2006. The largest single recorded wildfire in the state, the Thomas Fire, which resulted in the filing of more than $1.8 billion in insurance claims, occurred in 2017.” The Thomas fire actually was just surpassed by the Ranch Fire that started in late July. Per Wikipedia, in 2018, a total of 5,723 fires had burned an area of 1,250,467 acres (5,060.46 km2), according to the California Department of Forestry and Fire Protection and the National Interagency Fire Center, as of August 28. The active Mendocino Complex Fire has burned more than 459,000 acres (1,860 km2), becoming the largest complex fire in the state’s history, with the complex’s Ranch Fire surpassing the Thomas Fire to become California’s single-largest modern wildfire.
Plants suffer in the hot weather
With the record temperature, plants need sufficient water to survive and thrive. When not enough water is provided, plants show signs of stress, which can be seen everywhere. If the plants do not get enough water for too long, they will pass the point of being saved and just die off. To keep the lawn green, a large amount of water is needed to spray on it, otherwise it will go yellow very quickly.
A garden thrives in the hot summer
Some gardens, however, do not need any extra water versus usual, yet still grow well despite the heat. How is this achieved? This garden was first installed in early spring: After just 3 months, the plants grew in a lot, with beautiful blossom: This sage grew from a small plant to a bush in just 3 months, big enough for the hummingbird to visit:
After 3 months:
Another 3 months passed since late spring, it is the hot summer time with close-to-record setting temperatures. How do the plants do? They all do well! While the high temperature stressed out so many other plants, not here. The owner said he did not do anything after the garden was installed; he just let the irrigation run as first programmed, which is mere couple minutes each time, at about 3 times a week.
Keys to a robust garden in summer
There are several important reasons to the thriving garden. Plants All the plants selected are drought tolerant, such as California native plants, and succulents. The native plants are well adapted to California’s arid weather. They have very strong root system and can go very deep and suck in the water. That means, at very dry and hot times, they are better able to get water than other non-drought tolerant plants. Here you see a California native Monkey Flower can live off very little water, on a rock. When they are planted in a garden, for many native plants, after they are established, they don’t need any extra water all year round. They can sustain themselves from the water in the soil. Here is the same native plant Monkey Flower in the garden. Succulents are another type of plants that only need little water. They have no fear for dry and hot conditions – they thrive in it. Drip Irrigation Even though all the plants are drought tolerant, they still need proper watering to establish. Here, drip irrigation is the secret behind the water. When the garden was installed, for every plant, a drip line was placed around its root zone, so water can drip right into the root ball in the soil. As water is slowly dripped, it can be absorbed into the soil without any runoff. A irrigation controller was installed to control the watering frequency and length automatically. For this garden, just a short watering time was programmed, so the water usage is quite low. Mulch Mulch is another key piece for the puzzle. With it on the soil, evaporation is greatly reduced, and the moisture can be kept in the soil much longer. In addition, it will suppress the growth of the weeds, which take water away from the plants. The mulch is made from tree bark, which is organic. When it decompose, it will add organic matters to the soil, which will enhance the water storage capability, to allow it to hold more water, longer.
Much water can be saved versus lawn
In hot summer days, according to Ben Erickson, “While the amount of water needed will vary depending on your climate, the weather, and the time of year; the general rule of thumb is to make sure your lawn receives 1″ of water to your lawn per week during dry conditions.” So, for a 1000 square feet of lawn, in every week of dry conditions it needs 623 gallons of water, or, 89 gallons a day! A drought tolerant garden, on the other hand, uses much less. As it only lasts couple minutes each time, by drip, the garden shown above uses just about 1/4 of the water of the same size lawn. When you add up such drought tolerant landscapes, the amount of water saving can be really significant. When it is hot, everyone uses more water, so it puts a huge demand for the water supply. Unfortunately, the supply has been on the decline with the shrinking of the Sierra Nevada snowpack, higher temperature and other reasons. Here is the Guadalupe river, the river of the Silicon Valley, at the peak of summer. Here at Los Gatos Creek, a tributary to the Guadalupe river, the water was very low. However, the birds and other aqua animals that live in this habitat, like this hawk, depend on the water to survive. According to USGS, “Each Californian uses an average of 181 GALLONS of water each day. ” We then use half of that water on lawns and other outdoor landscaping to keep it green. Water is a very valuable resource, we may use it in a more efficient manner. On May 31,2018, California Gov. Jerry Brown signed into effect two water use efficiency bills, SB 606 and AB 1668. “In preparation for the next drought and our changing environment, we must use our precious resources wisely. We have efficiency goals for energy and cars – and now we have them for water”. “Establishing an indoor, per person water use goal of 55 gallons per day until 2025, 52.5 gallons from 2025 to 2030 and 50 gallons beginning in 2030.” An outdoor target will be announced later. For outdoor landscaping, we should aim to reduce the water usage from the current 50% of total to something lower. This can be best achieved with a water efficient garden. As we can see in the garden above, it needs much less water than that for a lawn. The drought tolerant plants can fill the garden with beautiful colors, and keep the water usage low even in hot summer days. Birds and other pollinators love the blossom and will drop by often to visit. It is hot out there. No more worrying about spraying more water on the lawn to keep it green. Just sit back, let the irrigation run as programmed, and enjoy the beautiful view the garden has to offer.