Native Plants… So Hot Right Now!

The story of July so far is heat. My Acurite Pro 5-in-1 Weather Center has been recording the temperatures. Here’s a screenshot from my Wunderground weather station app.

The temperature chart (upper left square) shows the high (top line), the middle line is the barometric pressure, and the bottom line is the low temperature for the day.

The temperature chart shows the daily highs and lows from June 12 through July 12. A month ago, June 14, the high was 92 and the low was 49. That’s a big difference from July 9 when it hit 112 degrees and the low was 72. From what I understand, the really brutal part of summer for my plants is the night time when it really never cools off enough for them. My vegetables, especially, seem to be suffering. I’ve got a drip irrigation system on them now, so they are getting the moisture they need. But, the heat seems to be affecting their production of fruit.

My native plants are adapted to the heat. Many of them go dormant in the summer. While there is variation among the plants, the cycle seems to be that they conserve energy during the summer. Water is pretty scarce so they survive instead of thrive. But, when the temperatures cool down in the fall, they prepare to grow and by the late winter, most California native plants are blooming and growing. For example, my desert willow trees drop all of their leaves during the winter and look dead. But, if you look, there are buds on the branches. When the weather warms, the tree sprouts leaves and grows. The summer is about flowers, seeds, and survival. A few plants, however, especially the younger plants, are still growing! I’ve seen new leaves on some of my manzanita. The white sages’ flowers are all but gone, now, their “wands” browning and ready to drop seeds, but they are sprouting some new leaves, too. But, the biggest story of growth this spring/summer has been my Gambel Oak!


You may be able to tell in the picture above, the two branches that are tallest are completely new growth just this season. Both of them represent two or more feet of new growth! It’s a big jump for a plant that heretofore has only shown inches of new growth in the past couple of seasons.

I have been told that there is a saying among gardeners that “first they sleep, then they creep, then they leap.” This Gambel Oak was planted back in June of 2015, one of the first plants I actually put in the yard. So, in all, it was two years ago, but it feels longer. Patience is important, I guess, with gardening, but it’s hard to cultivate that, pun intended.

The heat has been brutal but looks to be letting up a little. Yesterday it hit 101 but today is suppposed to stay in the upper 90’s and the same is predicted for the rest of week. But, we had multiple days of scorching heat, over 15 with temperatures topping 100 degrees. The heat makes watering difficult. California natives don’t like water in the summer time, mostly. While I’m far from an expert on such things, my understanding is that the native plants have adapted to the heat and the nutrient-poor soil by working with microbial organisms in the soil. These bacteria live on the roots of the plants and they fix nitrogen, I believe, that the plants then take in. The bacteria thrive when soil is cool and moist or warm and dry. But, they don’t like warm, moist soil. Too much moisture in the warm soil kills California native plants and some are more sensitive than others.

For example, I have ceanothus plants that absolutely HATE water in the summer. They even seem to dislike it in the winter, too. The leaves turn yellow and fall off if you water them too much. But, on the other hand, some of the plants do want some summer water, particularly if they are in the first or second summer season. I have this really great book by Helen Popper titled “California Native Gardening: A Month-by-Month Guide” in which she writes:

Do not overwater. In most of the state, summer water wreaks havoc with life underground. Not only does overwatering in the warmth of the summer promote the growth of fungal pathogens that lead to root rot and crown rot, it also harms beneficial fungi that link to their roots and enable them to take in nutrients and water efficiently. These links, called mycorrhizal links, enable the plants to ward off diseases, help them recover from drought, and improve the structure of the soil. The mycorrhizae exist in mature native gardens but they take time to develop in transitional gardens. Overwatering (or overfertilizing) disrupts the establishment of these unseen important relationships.

Overwatering also causes other problems. It needlessly encourages weeds and garden pests, such as aphids and gophers. In the parts of the state where irrigation water contains salts, watering during the dry season also causes salt to build up in the soil. While it is tempting to provide extra water for faster growth, hold off for now. Instead, water the soil deeply for survival, and hose off the plants once a month for looks. Irrigate, if you like, to stretch the natural rainy season forward a bit in fall and to push it out a bit in spring, but use restraint in summer. (Popper 128)

I try to follow the advice. But, we have had multiple heat waves over the last few weeks. I started this post a week ago and the heat is still hitting 100 every couple days and when it doesn’t, it’s still in the high 90’s. And it has been very dry. It feels better to us for the humidity to be low, but plants need some water. So, even though I think I shouldn’t, I feel like I should go out there and water.

Your humble author, making it rain up in the garden.

The thing is that many California native plants need a couple years of water before you can let them be during the summer. In a couple years my backyard should need little to no water at all. Only when I plant something new will I need to go out and actually water. The website for the Las Pilitas Nursery is another treasure trove of information   for California native plants and the author, Bert Wilson (now deceased), recommends spraying native plants to rinse off dust, but otherwise, not to water them. That’s what I try to do. But, some of my plants are still very young while others are close to being “established” in the yard, meaning their roots are developed and extensive enough to support the plant through heat and drought with minimal assistance.

The worst part, for me, is that I lose some plants anyway. My sticky monkey flowers always seem to brown and die in the heat. I’ve lost four of them this summer and several last summer. And the sages can sometimes wilt and die back in the heat. The worst hit has been my vegetables. My pumpkin plant stopped producing fruit after one pumpkin, as did my butternut squash plant. The zucchini vines withered and the tomato plants are struggling.

And, another issue related to this is that the wet soil attracts gophers. So, I had started watering more broadly over larger areas to try and confuse the gophers as to where the roots are, since I’ve had a lot of plants killed by the awful rodents.

Weather West, one of my favorite blogs says we should expect continuing hot weather of much the same intensity but with more humidity over the next week to ten days.

Has the summer brought any challenges to your garden? Lost any plants? Has it been unusually hot where you are, too? Feel free to add a comment!

 

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