Santolina is an herb said to be used in folk medicine to make a tea that expelled intestinal worms or was used as an eye wash. The plant repels insects, and placing leaves in sachets is said to repel moths.
We grow santolina (also known as lavender cotton) in our rock garden for its evergreen appearance, yellow button-like flowers and drought tolerance. It’s not native to North America, but does very well in our dry Southwest soil.
Gray santolina (Santolina chamaecyparissus) produces bright yellow flowers in summer. The plant has few matches for attractive gray-green foliage and its ability to spread as a groundcover. Our large one has been a cover for a litter of cottontails and is now spreading slowly over a rock wall.
Another variety, green santolina (S. virens or S. rosmarinifolia) has lemon-colored button flowers that contrast with its deeper green foliage. Both types of santolina have an aroma, and some people find the bloom aroma offensive. Most varieties of the shrubby groundcover grow in zones 5 through 9 and need only moderate water. Learn more about santolina varieties from Cornell University.
Caring for Santolina Plants
The plants prefer full sun, but our largest santolina blooms each summer even though it now gets lots of afternoon shade from a nearby tree. Place the plant in well-draining soil. When temperatures reach 90 degrees, water your santolina every few weeks if you get no rain. Otherwise, it needs water only monthly or less.
Prune (really, shear) santolina shrubs in early spring to shape and remove dead flower stems. Every two to three years, give the plant a harder prune down to about 6 inches above the ground to keep the plant from getting leggy. You also can sheer dying flower stalks after the first bloom for the chance of a second summer flowering.
The plant is evergreen or semi-evergreen in some climates. Santolina does best with no fertilizing. How easy is that? And you can take cuttings or divide larger portions of the plant in fall, although the transplants might succumb to cold, so if you can warm them the first winter, even better.
Whether you grow santolina for its herbal properties or appearance, you can grow that!
One of your houseplants or outdoor plants looks funky and you think something might be wrong with it. Your automatic response? Add water. Sometimes, that’s the best solution, and sometimes it’s just a waste of water, and maybe of your plant.
Wilt is a classic example of the dilemma gardeners face; wilting can be caused by both underwatering and overwatering. What’s more, factors other than water can cause leaves to wilt, even though the roots have plenty of moisture.
Here’s the thing: If too much water surrounds your roots, or they never have a chance to dry a little, the roots don’t get enough oxygen, which also is crucial for plant health. Further, some plants are susceptible to root rot. Let’s look at a few reasons to add water to help a plant, along with a few tips on when not to water.
How to Avoid Overwatering
Regularly check and maintain all sprinkler, bubbler and drip systems. Redirect flow amount or direction for any that appear to be getting too much water, and repair leaks.
The problem might not be how much water, but how you water. Many plants take poorly to regular watering of their foliage. Water that sprays evaporates faster (which is more wasteful) or can sit on foliage too long, leading to diseases. Spray irrigation also waters too much ground around a plant, helping weeds more than your shrub. On a sunny day, most of the water evaporates, but if you water late in the afternoon, on a cool, cloudy day or onto a thick or crowded plant, the water sits overnight on leaves. The best times to water overhead are to wash off dust that builds up on leaves (affecting photosynthesis) or to wash off aphids. But reserve these actions for sunny mornings whenever possible.
The soil is your best test for whether a plant needs water, not the plant. Check the soil around a houseplant or outdoor plant to see if it still is damp one to two inches below the surface. You can use your finger, a small trowel to gently push soil aside so you can see or feel it, or small tools like chopsticks of pencils pushed in and then removed to see if soil or moisture have stuck to the wood. There also are commercial soil monitoring tools available.
Mind the season. When plants go dormant in winter, they need much less water. You should adjust your schedule accordingly and try to avoid watering too soon in spring or too late in fall.
Have a way to stop automatic watering when it rains. Weather sensors are available for irrigation and rain-harvesting systems, and others have smartphone software. This helps you pause a watering schedule from work on a rainy day, for example. Although these systems are designed mostly to conserve water, they also prevent oversoaking plants. You can even get solar-powered sensors for watering with rain barrels. I reviewed one last year.
Water slowly, which is another drip irrigation advantage. The more slowly the water falls to the ground, the more gradually it penetrates. This is especially important for containers; fast, hard flows of water can wash potting soil nutrients right out the container’s drain.
When to Water
Always water new plants, seeds or transplants more often in the first year or so. Even though they are labeled xeric or low-water use, the roots need help growing in their new environment and the plant is more vulnerable.
On hot, sunny days. If you haven’t watered in a while and it’s peak summer heat, give plants with mostly dry soil, especially those most vulnerable to heat, a drink in the morning to help them get through the day.
Consistently for vegetables and edibles. It helps a tomato to nearly dry out some between waterings, but not to completely dry. Watering the same amount each time keeps the plant growing at a healthier rate and prevents fruit problems such as splitting.
No matter where the current drought monitor stands, New Mexicans and other Southwest gardeners know that water is precious. Luckily, plenty of native plants have adapted to the dry conditions of desert and intermountain regions of the Southwest.
Still, gardening responsibly anywhere demands attention to water use and waste. And people who want to grow food in their yards or on their patios can save water and money with sensible, waterwise strategies.
The good news is that the home and garden market keeps pumping out new tools to help gardeners conserve water but enjoy their landscapes. I’ve recently reviewed two products for Gardening Products Review. One of the products combines solar technology with rain or faucet water to support slow drip systems in areas of the garden.
The other product from a small startup company helps you water deeply near the roots of plants using a simple garden hose. Up next: I’m testing a cloud-based system to control watering from your faucet.
Check out these watering product reviews, along with lots of other reviews from fellow garden writers at Gardening Products Review’s website. And plan now for next spring’s waterwise plantings.
When approaching a new landscaping or planting project, it helps to gather ideas, whether you do so virtually or hopefully in person. A top benefit of being a member of the Association for Garden Communicators (GWA) is access to botanical, demonstration and private gardens.
If you travel, you can gather plenty of ideas from around the country. Even when I’ve visited the Northwest or Southeast, I’ve always found plant and design ideas or just enjoyed the gardens! If you want practical ideas you can apply in your own backyard, nothing beats a local botanical or extension demonstration garden.
Benefits of Demonstration and Botanical Gardens
Many botanical and demonstration gardens are designed primarily to educate. Extension master gardeners typically have demonstration gardens featuring native and zone-appropriate plants for their area. The city of Scottsdale, Arizona, has a xeriscape garden to demonstrate how local residents can save outdoor water use but have attractive lawns. The Albuquerque, New Mexico, Botanic Garden includes a demonstration farm that re-creates a 1930s farmstead to show how people can grow or raise their own food. And I love the Pollination Gardens at the Arizona-Sonora Desert Museum in Tucson.
The Tucson pollination garden teaches visitors about planting for pollinators, including Monarch butterflies. Most demonstration gardens help visitors learn about plants and especially how to grow them locally. But if you really pay attention, you also can learn a lot about design, containers and especially which plants or collections get you excited about gardening. Most gardens also offer classes or guided tours to add to the learning experience.
Finally, taking children to demonstration gardens can spark the gardening bug, especially for growing food. In fact, a study of demonstration gardens started by North Carolina county extension staff showed that between 2006 and 2010, the number of gardens made up of edible plants outpaced those with ornamental plants only or a mix of edible and ornamental plants to teach families about growing food.
Many demonstration gardens are run by extension offices of universities and the state extension’s master gardeners. Often, universities, cities and counties have gardens that serve dual purposes of beautifying office or park landscapes and teaching residents about gardening or local issues such as conserving water, saving pollinators, container gardening, producing food or gardening more sustainably. Hospitals can have meditation gardens on their grounds or demonstration kitchen gardens to help patients and families learn about growing healthy vegetables.
Others might be organized by private entities, and if touring an entire botanical garden seems overwhelming to the beginning gardener, or the gardener’s toddler, botanical gardens offer demonstration gardens within their exhibits. Visitors can make their way to the gardens on the map that interest them most. Remember, many demonstration and botanical gardens rely heavily on volunteers and fundraising to maintain their plantings.
Virtual Demonstration Gardens
Major botanical gardens might offer virtual tours, a nice tool if you can’t visit them in person and are researching local native or adapted plants for your own garden. If you’re on Twitter or Facebook, you also can follow favorite demonstration or botanical gardens and see photos or live videos. Or you can join an online community such as Plants Map to connect with other gardeners, organizations or resources that interest you. Organizations such as botanical gardens also set up collections on Plants Map.
Growing with organic methods is smart for lots of reasons, both personal and environmental. Although there are plenty of strategies gardeners and homeowners can use to save water with ornamentals, such as planting native and xeric plants, it’s a little tougher with vegetable gardening.
Tomatoes, for example, need consistent watering! But growing tomatoes organically can conserve water. Here are five ways how:
Organic soil retains water better. Anyone can improve their soil’s water retention by up to 5 percent by adding organic matter. It also helps to avoid use of chemicals and pesticides. Using pesticides and chemical fertilizers in gardens can throw off the natural balance of the soil, making it less able to retain moisture around plant roots and making fewer nutrients available for plants. On the contrary, planting cover crops in the fall and use of compost or other organic matter help restore valuable soil nutrients. Organic matter also helps soil structure for water infiltration and retention. Healthy soil can respond better to drought conditions.
Organic growing protects water supplies. By avoiding chemical pesticides and fertilizers, gardeners also protect the water supply. Pesticide chemicals can remain in the soil for years; some are more toxic than others and break down in the soil more slowly. The chemicals from these products can run off into bodies of water, such as rivers. And eventually, they can seep into groundwater. That might seem a distant concern to some urban gardeners, but those of us using wells live right above available water. The more chemicals that run into water supplies, the less safe drinking water is available.
Use of mulch reduces evaporation. A layer of appropriate mulch above the ground around a plant helps reduce ground-to-air evaporation, making the soil take longer to dry out. The mulch also helps cools plant roots. Using organic mulches such as bark, nut shells, compost and others adds organic matter to the soil slowly over time for an added bonus.
Organic methods can minimize erosion. Traditional gardening and farming uses rototilling and deep plowing to turn the soil before each growing season. Plowing deeply and turning the soil over can disrupt soil microorganisms, harm soil health, and place looser soils on top, where they’re subject to erosion from water and wind (think Dust Bowl). No-till methods help control erosion and build soil structure. The soils, in turn, better retain water. This can be a problem if the soil drains poorly, but a definite help in low-water regions. Not tilling involves building up beds with organic matter, much like nature does as plants drop leaves that decompose. If you want to work organic matter in, it’s best to grab a shovel. A broadfork is the best tool for breaking up compacted soil.
Growing organically creates healthier plants. Healthy soil is the foundation needed to grow healthy food. When soil has good nutrients and structure, it supports root growth and uptake of nutrients, improving plant health. Plants that are not healthy are more vulnerable to insect and disease damage. The plant might not use water as it should when it’s stressed, and the gardener certainly guesses that if a plant looks bad, it needs water. So, keeping plants healthy saves the extra water the plant needs or gardener applies in times of stress. And healthy plants keep on going, so you don’t waste water on establishing a plant that later dies from poor conditions.
We’re trying to add more wildflowers to our garden and create small meadows around some areas of the property. One of the challenges in choosing locations and flowers is munching deer.
Our deer population is not huge, mostly because of a previous wildfire in the forest north of us. I don’t want to exclude deer from the property and am happy to let them graze our grama and other grasses all year long. Although we seldom see the deer once summer days heat up, we see evidence of their munching from time to time.
Blocking deer is the best way to keep plants safe. But it’s much easier to fence around a tree, bush or vegetable garden than it is around a wildflower meadow. Fencing kind of ruins the effect. So, the best way to keep deer from eating the flowers is to plant “deer resistant” varieties. The quotation marks refer to the fact that our deer have not read the plant descriptions. They avoid several plants completely, but every so often, we find surprising telltale signs of deer damage. I think it’s difficult to guarantee deer resistance for most plants.
We recently ordered a deer-resistant wildflower seed mix from High Country Gardens that we’ll plant after the first hard frost. Not all of the plants bloom the first year, which is disappointing, but we’ll plant a few deer-resistant annual plants to fill in so the meadow looks colorful for a special event we’re hosting next summer. Here are some of the flowers included in the deer-resistant wildflower mix:
Yarrow (Achillea millefolium); Lanceleaf and plains coreopsis (Coreopsis lanceolate and C. tinctoria); Foxglove (Digitalis purpurea); California poppy (Eschscholzia californica); red poppy (Papaver rhoeas); and the trusted blanketflower (Gaillardia), along with several types of lupines (Lupinus) and sages (Salvia).
This wildflower mix needs full to partial sun – at least six hours of sun a day. We have a few areas that are shadier, so we’re still looking for an easy solution there. In April, I wrote about five drought-tolerant plants that love shade. Columbines come to mind, of course, but some salvias take at least partial shade and are deer resistant. Then again, some shade lovers, like hostas, attract deer. We’ve also got some rocky areas, and plan to sprinkle white love-in-a-mist (Nigella) seeds and gathered larkspur (Delphinium consolida) seeds this fall as well.
Keeping deer out of meadows
One strategy for keeping deer out of wildflower patches is to surround the area with aromatic plants that deer avoid, such as lavender or rue. There are lots of deer deterrent products; I’ve had success with Messina’s Deer Stopper spray on plants in our xeric garden that deer had previously disturbed. The product remains effective for about 30 days, but I have to remember to spray regularly for continued protection. Spraying an entire meadow would take way too long, but I think the spray could be really effective on those flowers we’re most concerned about or know deer have eaten in the past.
Finally, if uncertain about the best wildflower choices for a meadow, work with what you have. You can try gathering seeds from native plants or leave the area unmowed at the end of the season and let nature spread the seeds for you. I’ve done that in an area with a higher grama-to-weed ratio, and hope that each time I walk through it, I spread grama and flower seeds. We pulled as many weeds from it as we could to give the native plants like grama, wild blanketflowers, verbena and daisies a better chance of reseeding.
Note: Messina’s sent me a free sample of Deer Stopper spray, but did not influence my use or review of the product.
Gardeners often choose plants more for their flower color or ease of care, and that’s a great way to enjoy a garden. If you want to add interest to a xeric bed or lawn, it also helps to consider plants’ shapes and textures. Shape, or form, refers to the circles, lines and squares of plants or how you arrange plants. Texture relates to how coarse or fine a plant looks and even feels.
For example, there’s a reason why many professional container arrangements usually include a grass or similar plant with tall, thin blades. The grass rises from at or near the center of the pot, adding height. The long, slender blades of ornamental grasses also vary the shape and texture of the arrangement if it’s filled with low-growing, round flowers. You can do the same in your xeric garden.
Although it can be tough for some gardeners to adapt to the Southwest after owning lawns with formal cottage gardens, they eventually learn to love the look and easy maintenance of more native, “unsculpted” plants.
Although some landscapes look great with rows of the same plant, most xeric gardens have a more natural feel. The designer or home gardener can use a variety of low-water plants to vary shapes. For example, if you want to plant cacti and succulents in your container or garden, you aren’t likely to choose all prickly pear cacti (Opuntia). Their round pads and medium-height spread complement a spikier ocotillo (Fouquieriaceae) or a spiraling sedum groundcover.
The shapes in xeric plants typically are less defined. Still, plants have a basic shape, such as how lavender stalks form a rounded V.
Those who desire a more balanced or symmetrical look can repeat a plant. Some of the most effective landscapes I’ve seen have a row or grouping of xeric ornamental grasses. Individually, the grasses have a wispy, wild look. But when placed in a grouping, they sway in the wind together and create a clean line. Too much variety can cause a xeric garden to look more like a botanical garden full of eye-catching plants with no flow if not designed by professionals.
Foliage and texture
Many xeric plants produce remarkable flowers, and some bloom throughout the growing season. But one way xeric plants survive is with relatively smaller foliage. Less leaf area means less transpiration (water evaporating from leaves) and improved survival chances in arid climates. Still, a waterwise garden can include foliage variety in texture, size, shape and color.
Some xeric plants, such as pineleaf penstemon (Penstemon pinifolius) have tiny, needle-like leaves. These contrast nicely with nearby plants that have rounder, lusher foliage, adding varied shapes and textures to the garden.
You also can add texture with hardscape materials or yard art. Hardscaping materials include just about anything that isn’t a live plant. So, for example, you can add interest around a rock or boulder with a plant that has small, twisting or draping branches. A post fence has lines that run up and down, and I believe that a mix of small, round or trailing plants look better against it than a line of tall or upright plants. Hardscape items also add texture, such as rough rockiness or smooth backdrops.
Rhythm is an important landscape design that can be achieved with cautious repetition of shapes, curves and layers. Some of the best designs have layers. For example, you can plant a groundcover (a low-growing or trailing plant that typically spreads) in front of a shrub that has long, thin branches and few flowers.
When layering plants, or in any planting, it’s important to consider a plant’s mature size. If not, your nice round shrub might catch up to or even block the tall one behind it. It also helps to know a little about pruning. You don’t have to shape plants into animal characters, but it helps to know how to trim the plant for its health and growth (even control of growth). Otherwise, plants can later upset balance and rhythm in the garden.
Hardscaping is use of anything other than plants, really, in the garden. So it includes rocks, fences, walls, walls made of rocks, pavers, stepping stones, lighting, gravel (made from rocks) and found or repurposed objects. Did I mention rocks?
Here’s the problem: When people think of xeriscaping or converting high-water lawns and landscapes to more waterwise plans, they often turn to landscape gravel, rock borders and concrete to fill their landscape. Done! But the best xeric landscapes mix functional and attractive hardscaping with plants for full effect.
Pros of Hardscaping
I find that after touring a public or private garden, my photos often include fences, garden art and other hardscaping features. I guess I’m drawn to them. Any plant can shine when placed before a solid wall or large boulder, but those with tiny flowers and foliage really pop with a backdrop. And you don’t have to use large, expensive artwork or structures. Sometimes, all you need is a well-placed rock or container.
Aside from aesthetics, hardscaping features provide function in the landscape. Pathways lead the gardener, visitor and the eye in the best direction, or help a homeowner get from one point to another more easily. Fences and walls improve privacy and arbors and pergolas add to shade in sunny garden spots.
Finally, homeowners often put in hardscaping to minimize watering and plant care. Most nonplant items in the garden require little to no care and last for years.
Cons of Hardscaping
Replacing lawn and plant materials with hardscaping can lower maintenance, but can create too much heat in the lawn and garden. A concrete patio or gravel-covered yard is way hotter than turf and plants. That being said, a mix of both helps lower water use and costs. If done right, homeowners can enjoy their gardens and save water.
Only plant materials provide important food and pollen for animals and insects; bushes and trees also provide better shelter than the eaves of your home. Adding birdhouses and beehouses near plants can help nature’s garden visitors. Too much concrete and gravel also makes a garden seem unfriendly to people. You probably want privacy and a place to sit or walk, but don’t you also want flowering or edible plants nearby? If a big patio is necessary for entertaining, add container plants on the ground, walls or even the furniture.
Finally, be sure to consider existing trees and other plants you plan to keep when converting lawns to gravel. Trees need deep watering, and the roots stretch out at least to the tree’s canopy, which is how far out branches and leaves extend. So providing a pretty little circle of mulch around the trunk likely isn’t enough.
Some of my favorite xeric landscapes combine a few featured plants such as a shade tree or colorful bush with low-growing annuals or groundcovers that cascade over steps or rocks. Combining hardscape and plant features is a smart xeriscaping strategy and a way to enjoy your lawn for years to come.
I love the herbs in our ornamental garden, many of which are low-water plants. Letting an herb such as sage flower can add color and lots of bees to your landscape or patio.
Herbs typically begin to lose flavor as they flower, however, so if you want to eat herbs from your kitchen garden, it’s best to harvest often and enjoy the fresh flavors from plants you grow on your own. Harvesting herbs usually invigorates the plant, much like pruning or deadheading ornamentals. The best of both worlds? Having space to let one sage or thyme go to flower while you harvest from another sage or thyme in the same season.
The choices for herb gardens are endless, and it makes most sense to choose the plants you like based on your zone/growing location and favorite flavors or most useful purposes (such as medicinal). I grow mine for the color, scent and flavor and to sell at the farmers’ market. That presents its own set of challenges, mostly transporting herbs and keeping them fresh when it’s hot. Way too hot.
With nearly all herbs, you’re better off harvesting in the morning and using a sharp pair of scissors or trimmers. It’s also best not to wash herbs before short-term storage, but instead wait until just before preparing them. Here’s a list of simple harvesting and storage tips for several herbs you can grow year-round or as annuals, along with a link at the end for a previous post on drying herbs.
Basil. Pesto anyone? Basil is easy to grow, but a little tricky to keep fresh after cutting. You would think that rinsing the leaves and keeping them chilled in the refrigerator would keep them fresh for days. But you would be mistaken. First, harvest basil in early morning. I’ve written in the past about how to cut basil, along with an easy pesto recipe in the same post. Of course, you can always harvest a few leaves only and use them right away. If you want to keep basil leaves fresh, the best approach is to avoid washing the basil after harvesting and placing stems (no leaves) immediately into a jar of cool water. They do best stored at 50° F, but who keeps their house or refrigerator at that temperature? If you have a spot, great. If not, keep the glass in a cool, lightly sunny spot and change the water often. It can keep for weeks in the right circumstances.
Cilantro. Cut off no more than one-third of your cilantro plant leaves after the plant reaches at least 6 inches tall. The best way to store cilantro leaves is to place the stems only in some fresh water and put the entire jar in your refrigerator. You also might want to loosely cover the aromatic leaves with a plastic bag.
Dill. Dill leaves, or weed, also are best stored with the stems only in water. Alternatively, you can wrap the entire stem with the leaves in a damp paper towel and place the herb in a warmer spot of the refrigerator, which usually means the door. Don’t be surprised if the herb’s quality goes down soon after storing. The freshest dill is harvested as cooks need it. Dill tastes best when harvested just as the plant’s flowers begin to open. If you want to preserve dill seed, wait for the flowers to turn into seed heads and dry up on the plant. Remove the seed head when it turns pale brown.
Lavender. More people likely grow lavender for its beauty and as a pollinator than for eating. There are varieties of lavender that are more suitable to culinary use (see a recipe here or check out our Lovin’ Lavender Pinterest board. If harvesting lavender for a recipe, it’s best to cut desired stems early in the day after they dry from morning dew. Even when fresh, you can harvest buds easily by rubbing the flowers between your hands or fingers. This is even easier to do when the herb has dried somewhat. When cutting branches for arrangements, cut all the way down to the main plant, being sure not to cut into the woody branches. Depending on where you live, weather conditions for the year and when you harvest, it’s often possible to get a second bloom from lavender each summer.
Rosemary. Harvest rosemary any time of day or during its growth. We’ve harvested fresh rosemary in fall and even winter. As with lavender, avoid cutting into the woody branches of rosemary when trimming or harvesting. Select a few sprigs and either use the leaves right away or store unwashed, loosely wrapped in plastic in the refrigerator drawer.
Sage. Fewer people use fresh sage leaves in the kitchen; many recipes require ground or rubbed versions of the herb. But there is plenty of value in the herb’s leaves, including medicinal uses and smudge sticks. I love to place fresh or dried leaves into the cavity or under the skin of chicken. For short-term storage, sage can be wrapped lightly in plastic and placed in a refrigerator door. It’s best bundled for drying, however. Just in time for fall dishes!
Thyme. Thyme also should not be washed until used and harvested before flowering (for culinary use) when possible. Keeping thyme trimmed and enjoying flowers on other forms of thyme, including ground covers, gives you flowers and flavor. If planning to dry the herb, you can wash it gently and let the leaves dry before bundling to hang a bunch. I’ve picked a bunch and placed it in a decorative bowl near the dining area, just so I can get a whiff of the herb while inside. Thyme retains flavor quite well after drying.
When it gets hot for a day or two, plants can wilt and require some extra attention. That’s pretty easy to understand. After all, I spend less time outside in the heat of the day because I wilt. I also drink more water. After more than a week of temperatures hovering near or above 100° F, our plants are showing other signs of heat stress that we less often consider.
You would think that living in the Southwest and having mostly xeric plants means plants can tough it out dor a few hot, dry (windy!) days. That’s partially true. But these temperatures are way above normal, at least for an entire day/week and more. Normally, July 1 marks the beginning of monsoons, where clouds build and drop at least some rain in the afternoon, giving the plants and me a break. Not this year. And it’s causing problems for nearly every living thing in our garden. Here are some reasons why:
Heat can reduce bee populations
We noticed about midway through our current heat wave that we seem to have fewer bees in our garden. Of course, I thought I was imagining that. Nope. Bees are especially sensitive to temperature and its regulation. Temperature particularly affects young bees, which are important for keeping colonies going. They tend to keep their hives at 95° or lower, and stress when the temperatures exceed 98°. Bees also need water, and we’ve had two weeks with no measurable rain and consistently high temperatures, even for our evening lows. Here’s a great explanation from Tufts University on how honey bees keep cool (and warm). Despite the fact that we have plenty of flowering plants for bees beginning in spring, the population is lower this summer. I was pleased to see a few survivors on our lavender this weekend, but this is a brand new worry!
Lack of flowering or fruiting
Those bees! They also help pollinate our ornamental plants and especially our vegetables. So, there’s one concern in heat. But I recently was reminded how heat also affects flowering and fruiting. It turns out that pollen loses its effectiveness in high heat. Even though we’ve hit the 100° mark before, I can’t recall it lasting for days and weeks since we’ve been growing tomatoes and other edibles in New Mexico. What’s more, drought lessens the chance that pollen can stick to a female flower.
This is the heat issue we best recognize – leaves wilting on a hot day. Plants “sweat” to cool themselves like we do. With transpiration, water travels up from the roots and to the leaves, where it evaporates through tiny pores under the leaves. So on a hot, dry day, the soil, roots, and entire plant dry out more quickly. Add some wind just for fun, and a plant can wilt or stress. Plants can take more water, but only up to a certain point. Some plants have plenty of moisture and experience what’s called “incipient wilt” during peak heat each day. If they recover by morning, the plant probably is getting plenty of water.
Sunburn and sun scald
Plants can get sunburned. The sun can scorch leaves of plants that typically need a little more shade or lower temperatures. And many plants can burn on super-hot days. The sunburn often leads to brown spots or browning and dying of entire leaves. Sunburn of a few leaves shouldn’t be a problem, but a sign to shade or move a plant if possible. Sunscald is similar damage to bark in high temperatures.
Entirely new or different insects
Aphids, which can be controlled organically, tend to love cool, moist weather. Every type of insect is different, but they’re cold-blooded creatures. Insects can’t internally regulate their temperatures, so they rely on what’s happening in their environment. I’m certain that both weeds and insects change each year depending on weather. Cabbage loopers and leaf miners like heat. Ants? Don’t get me started. And dreaded grasshoppers thrive in drought. When a plant already is stressed by heat or drought, it’s more vulnerable to insect damage or insect-borne diseases.
Some plants adapt better to heat than others. However, young plants still might need more frequent watering in high heat. That’s the part that’s getting to me most. We have some new plants we put in the ground not long before the heat wave hit, and they’re struggling. We’ve even had to water a few xeric and waterwise plants that typically thrive with no water at all. It’s all part of the fun of gardening in the Southwest, I guess. See my previous post for tips on helping plants survive extreme heat.