How To Select Blooms For Heat, Hurricanes, And Humidity
Here is a plan to add heat-tolerant, vibrant annuals for the dog days of summer. We all appreciate the festive color that annual blooms add to our gardens, and we all want to extend our season through the ‘dog days’ of summer. This article aims to highlight those annual plants that will take our spring gardens all the way to the season’s end. The goal is to avoid those mid to late-summer bare spots when the season’s early promise of beauty fades to garden bugs and boredom.
Summer Planting Goals
I am a subtropical climate gardener, and my two points are:
- First, to define the plants that work best in our subtropical garden.
- Second, to show how our torrid gardening environment can help you appreciate the challenges of gardening in seasonally extreme heat.
Annual Bedding Plants Defined
An annual bedding plant is one that completes its entire life cycle, birth to death, seed to seed, in a single season. It does not die back and reappear next year. (It may, however, produce seeds for the next year. I say may because so many of the most floriferous of the brilliant new cultivars produce few,if any, useful seeds.) This is because they are bred to produce blooms, not seeds. Remember, our plants can do lots for us, but they can’t do everything!
In temperate climates, we call these plants annuals because of their temporary nature. They tend, however, to be actually perennial plants in tropical climates. So, some of these plants that I grew as annuals in our family’s northern gardens are perennial in our Zone 10 South Florida garden.
If you are north of Florida’s Zone 9, consider the plants on this list a seasonal commitment, and you will be successful.
Gardening In The Dog Days-What The Climate Has Taught Us
Zone 10 in South Florida is an extreme climate. Six months of dry and moderate weather, perfect for growing most crops (with supplemental water), are followed by six months of extreme heat, hurricanes, bugs, and humidity.
Our unique advantage is that we can garden for all twelve months of the year. The gardens we grow can produce something beautiful to look at and something delectable to eat every day, but our ‘Dog Day’ summers require selective planting if we are going to succeed!
What Effect Does Extreme Heat And Humidity Have On Plants?
The time when we want to stop digging and jump in the pool is the time when the plants are also ready for some relief. Here are the most important plant growth processes that are affected by heat.
- Transpiration and Water Loss increase-we notice water loss in both leaves and stems. Foliage will roll, have dry edges, and wilt. This will result in reduced flower production.
- Photosynthesis and Respiration in these processes, the plant utilizes oxygen and carbon dioxide to produce energy and organic compounds. Extreme heat can make these processes less efficient and retards plant growth.
- Water and Nutrition Uptake is affected by extreme humidity and can reduce plant growth.
- Pests and Fungal Diseases are increased by extreme humidity.
Water And Mulch
The plants will require more frequent water and the protection provided by organic mulch. The issues we see all summer long you will see in the later ‘Dog Days.’ It helps to be aware of what can happen before the problems arrive.
What We Mean By ‘Dog Days’
Think of the Greeks and Romans, who made their decisions by looking to the stars. They observed, in summer, that the dog star Sirius (The brightest star in the dog-shaped constellation, Canis Major) appeared to rise alongside the sun in the northern hemisphere. They deduced that the heat must come from the combined power of the two bright stars. So they called summer ‘Dies Caniculares,’ the days of the dog star. They noticed that the parallel rise of the two stars coordinated with heat, drought, hurricanes, bad luck, sickness, and mad dogs!
The old Greeks and Romans may have confused causality with coincidence, but they got the basic idea right. The ‘Dog Days’ are tough on all of us, plants, animals, and humans!
Keeping A Healthy Perspective About Flowering Annuals
For us gardeners, there is a fine line between being negative and the other extreme, becoming optimistically impractical. This makes me think about the great line from a famous old musical.
“Summertime and the livin’ is easy…”-George Gershwin
It’s not always true.
We lounge at the pool, go to the beach and enjoy the garden’s blooms, but it is not all wandering around the garden beds cutting roses. Summer is our time for heat and humidity wherever our gardens are, and there are some actions we can all take to make life easier and the gardens more beautiful.
Getting The Most From Annual Blooms In The ‘Dog Days ‘
Here are the plant selection, planting, and maintenance practices that will get the best results in extremes of heat, hurricanes, and humidity.
- Select The Most Resilient Plants-those resistant to heat-related diseases.
- ‘Right Plant-Right Place’-know your sun/shade/temperature and microclimates.
- Healthy Soil, Complete With Organic Matter And Drainage-prepare the soil prior to planting.
- Use Large Containers-these will hold more water and reduce watering time.
- Plant In Distances To Allow For Air Circulation-note plant spacing on the plant label.
- Water Frequently, Deeply, And In The Early Morning-this helps plants retain water.
- Mulch With Organic Material-decomposes slowly and increases nutrition from the soil.
- Regular Fertilization Program-avoids over and under-feeding.
- Stake Tall Plants As Needed-protect plants from summer wind damage.
- Observe The Garden Daily-goal is to catch problems when they are small.
How To Find The Best Annuals For Your Summer ‘Dog Days’
How to Find the best plants for your own Garden? Here is what we have learned by gardening in a wide variety of climates. The gardens we have grown were all very different, but the most useful procedures for finding the best plants are pretty constant.
- Utilize your local University Extension Service-your county should have one. Here is how to find it. We are volunteer Master Gardeners trained by our state agricultural college to assist our neighbors with backyard gardening. There is a wealth of resources available to you and free, too. Your local county service will be focused on your climate.
- Shop at your best locally owned garden centers-they will offer plants proven to work in your local areas. Ask for advice; you will meet real gardeners who spend all day talking to other gardeners.
- Know your climate-first find your plant hardiness zone. Use this chart and add your zip code. Then learn about your own garden and its microclimates. Our front garden, for example, is southwest facing and offers little relief from the sun. As we planted trees, our rear and side gardens developed as part sun. We garden pondside and need to be prepared for possible summer floods in some spaces. (In Hurricane Ian and Irma, the pond came disconcertingly close to the swimming pool. We can plant a little differently in each section. Map out your garden and be prepared for changes as shade plants grow and make changes to your light conditions.
- Visit your best local public gardens-see what grows for them. Public gardens are always trying out new ideas. You can see how well specific plants are working for them. (The link is for the American Public Garden Association.)
- How to Identify Your Plants-here is how to identify plants by their botanical names, I have a few tips on how to recognize and remember the names.
Best Annual Blooms For The ‘Dog Days Of Summer
Use these plants in the extremes of heat, hurricanes, and humidity for garden color. They work consistently for our own garden and for community gardens we have been associated with. Try to keep abreast of new cultivars offering colors, sizes, shapes, and disease-resistant features. You will be pleasantly surprised by the improvements the plant breeders are making.
What’s Important In Planting Annuals For The ‘Dog Days!”
First, Expect Good Choices of Plants and Varieties
Annual flowers are such a big business that there are research institutions and growers always ready to make improvements. If you want a certain color, size, or feature, it probably exists. Search the universities, the online growers and dealers, and your best garden centers. You will find something you can use.
Learn the important features and limitations of the plants you like and find the best of them.
Note the common features of summer annuals. The need for superior drainage is an obvious one; sun and shade positions are another. Ammending the soil and putting the ‘right plant in the right place’ will make a good start.
Save the names of natural varieties and greenhouse-grown cultivars that work for you each season. This is the value of garden calendars and journals. When you find a newer one that may be superior, test it alongside your favorite. Which worked out better?
Recently we discovered a Vinca with superior disease resistance and Impatiens (sunpatiens) with wonderful new colors!
My List Of Reliable Annuals For Summer’s Dog Days of Heat, Hurricanes, And Humidity
Did you love to snap the snapdragons as a child? I did! Everyone loves a snapdragon, which signifies springtime to many of us, but their beauty will fade when the real summer heat arrives.
Angelonia, native to the West Indies and Mexico, has not been with us northerners for long, but varieties of the plant are rapidly making a place for themselves in our gardens.
With an upright, bushy growth habit and a grape or vanilla-like scent, Angelonia adds beauty to the garden in all the ways we like to use annuals and last for us until fall. In our Subtropical climate, we plant a few snapdragons for the winter, but the Angelonia can live through different seasons and give us several years of pleasure.
Water in summer is critical; even in our rainy season, heat increases the need for frequent watering on dry days. The increased water means fertilizer washes through the plants, especially in containers. Follow regular waterings with a regular fertilizing program using a time-release, balanced fertilizer.
Make a note on your calendar so you know when to schedule the next application.
The Gardens And Plants In Our Lives
Whenever I try out a new plant, like Angelonia, I think of the old plants my family loved. My mother and grandmother valued impatiens for a little color in their New England summers. My sister, my daughter, and I all have offspring in the gardens of our family plants.
My point is that we all love our gardens and the continuity they bring us. Just don’t overlook the new ideas that plant hunters and growers are creating for us. The history of gardening is filled with gardeners adding new plants found in other places. Our ancestors would not have made that mistake!
You will find Angelonia in many shades of white, pink, lavender, mauve, and purple. Use them as a thriller or filler in your full-sun container gardens. You will find them in sizes ranging from 12-24′ tall and from one to two feet wide. Check the varieties for features, as you should expect a growing offering of new varieties.
Caladium-Caladium (caladium is the genus)
I am cheating here; this is a bulb. It is, however, a perfect source of colorful foliage for all-day, everyday color and pattern. In our climate, where finding summer color is challenging, they are a garden saver. The bulbs are easy to dig up and store over the winter, the prices when buying bulbs are low; and for these reasons, they are growing in popularity in northern gardens and are cost-effective even when used as annuals. They survive heat, humidity, and heavy rains and seem to have no predators. (In wet conditions, the tubers will rot. Store in dry conditions and plant in places with good drainage.
Almost the entire world’s supply of Caladiums is grown in a single town, Lake Placid, Florida. in 2022 the crop was badly damaged by Hurricane Ian. If the price and availability are an issue this spring, try again later.
The species of Celosia, native to the Mediterranean or perhaps East Africa, are thought to be the origin of the Celosia we use as annual plants. (Other species serve as food crops.) Their value is in the striking shapes and colors, and they are particularly effective planted in groups. They may appear to be oddities, but the flame or feather-shaped varieties seen in the top right blend well with other plants.
They perform successfully in full sun and require superior drainage. For this reason, they are more successful in beds and borders than in containers. If using containers, raise them on planter feet to ensure no water pools below the roots.
The Celosia will bloom abundantly all season long. You will find extremely vivid flower colors as well as many foliage colors. Keep them in mind; they may be just what you need for a special spot.
Coleus, a beautiful addition to an interesting and attractive garden, is a perfect example of how fashion invades every area of our lives. The detail-conscious Victorians loved ‘bedding plants.’ They loved to plant to form the appearance of an oriental carpet outdoors on the lawn. The Coleus, with brilliant patterns within its leaves, was a hit to our 19th-century ancestors. Then as the labor-intensive practice of ‘bedding out’ lost favor, so did the Coleus. This made the plant move from fashion leaders to fashion outcasts as the century ended. But they are back today and with a vengeance.
Use the colors and patterns of Coleus anywhere you will appreciate them. Edge walkways fill hanging baskets and window boxes and beds and containers. Clip off the insignificant flower that Coleus produces; this will extend the life of the plant. You should enjoy them until the cold weather. You can bring a few indoors for the winter. We expect to see them in our hot climate gardens for two or more years.
Native to Southeast Asia and Maylasia, Coleus may have been grown as early as the 1700s in Europe. Plant most varieties in part sun (six hours or less) or dappled sun. Check the varieties, as some are bred to perform in full sun.
Cosmos, with their tall stems and daisy-like flat flowers, come in colors including white, pink, orange, red, yellow, and maroon. The shape of the flower can be open or cup-shaped, and the flowers are large at 3-5″ wide, and they attract bees, butterflies, and hummingbirds.
Two hard-to-find features are that they grow easily from seed and make superior cut flowers. Each individual flower will last about four days, but the flower stems have multiple blooms, and these will continue to open on your cut flowers.
In summer winds, they may require staking.
Use lantana where you need color and interest for both humans and pollinators in places with full sun, humidity, and moist soil. Lantana is an ideal plant for hot and dry gardens. The plant is a fast growing, profuse bloomer with tiny tubular flowers growing in flat-topped clusters. They customarily bloom in a bicolored pattern. Lantana will accept soil pH that is neutral and both slightly acidic or alkaline. The plants are sturdy in the summer heat and unfussy as to soil.
In the ground, the plant has little need for fertilizers; use a balanced fertilizer in containers.
Marigolds are in the Genus Tagetes, with the most common species being Tagetes erecta, also called Mexican or African Marigolds, and can be tall, three to four high. Tagetes patula, the smaller bushier French Marigold, and Tagetes tenuifolia, the smallest signet Marigold.
There are over fifty species of Marigolds, but for ornamental gardens, you will primarily find the three listed above.
If the flower you need is usually small, bright, sun-loving, and tolerant of various soils, the Marigold is for you. Their distinctive scent is likely to deter marauding deer.
Here are the essential features of Marigolds.
The plant name is pentas, which is its Genus name, and pentas is both singular and plural. Also called Egyptian Star Flower for the shape of the individual flower in each cluster, the plant is a woody perennial native to areas from Yemen to East Africa. It is used as a popular annual in many parts of the world.
Salvia thrives in full sun and dry conditions in various qualities of soil. The Salvia used as annuals usually have longer blooming seasons than those used as perennials. In buying annual Salvia, you will see these names.
- Pineapple Sage-Salvia elegans it is annual in zone 4-7, sports a bright red color, and has a scent like a pineapple.
- Gentian Sage-Salvia patens, it has large blue flowers, reaches 18″ tall, and is annual in zone 4-7.
- Bedding Sage-Salvia splendens; is annual in Zones 5-9 and is usually 12-24″ in height and comes in a variety of colors.
For all day, every day, constant color, and lasting all season, try Vinca. The Annual Vinca plant (don’t confuse it with the ground covering vinca or periwinkle) is a tropical perennial and popularly grown as an annual in nontropical regions. We value it as a flower factory (compare it to impatiens) with bright flowers, often in bi-colors and shiny, leathery leaves. It is native to Madagascar and thrives in the sun. They will do best in well-draining garden soil but are not demanding and will grow in average soil, and are drought tolerant.
Expect a wide variety of colors, often with contrasting center rings, and a size of about 12-18″ high. Use them in beds, borders, and containers of all kinds.
It should perform all season as a low-maintenance option as it does not require deadheading.
Zinnia is an annual plant, growing from new seeds every season. It produces single, daisy-like blooms and lots of them! Look for a good choice of color, size, and shape for full sun locations.
You can choose from these shapes:
- Single Blooms-a single row of petals and a visible center.
- Double Blooms-mounded with multiple rows of petals.
- Semi-Double Blooms-some multiple rows, but you will see the centers.
- Shapes like beehive, button, and cactus.
- A good choice of sizes for the front and back of the bed.
If you are planting to attract pollinators, they will be able to use the single blooms at which they can access the pollen.
Zinnias are adaptable plants, but your plants will perform best in full sun (6-8 hours), with good air circulation and moist organic soil. The best pH is from 5.5-7.5. They will bloom all day, every day.
My Runners-Up List Of Annual Blooms
Use ThesePlants In Gardens in Temperate Climates
These are annual plants that perform perfectly for us all winter long and tend to survive our summers. We retain a few every summer, but the probabilities are not completely with us. They, however, have been successful in our cooler climate gardens.
My point here about choosing plants for the garden is about the expense, spending dollars, and labor hours. We all love to take a little risk on a new plant or two, but when we are planting many trays of one thing, we need to be reasonably sure of the outcome. It’s fun to take a little risk with the garden; just make sure you can accept failure!
Begonia semperflorens is the hybrid fibrous rooted plant we call wax begonia and is the annual version we grow for all season-long blooms. There are also perennial versions of begonia. You can propagate the plants from cuttings and have more plants and use them even indoors. They are called semperflorens, you guessed it, because they are always blooming!
This low-growing plant will bloom in red, pink, and white, with the added bonus of thick and shiny green leaves. They are also available with a bronze leaf.
Give your begonia bright but not direct light. (morning sun will work) and moist soil. Its fertilizer requirements are fairly low. Mix a weak fertilizer every two weeks for the best results. Pruning needs for begonia are minimal; just remove any broken branches.
There are places in the world where you cannot lead a civilized life without windows full of geraniums. In the rest of the world, the flower is almost as ubiquitous. Can you picture a small town Fourth of July or a perfect shopping neighborhood without its window boxes?
The geranium has been in European countries since the 17th century, and they have by now embedded themselves in our lives.
We picture geraniums as disk-like clusters of flowers above heart-shaped or round leaves, and we use them all summer in planters and window boxes. But we are looking at a plant that is actually a Pelargonium, a plant native to South Africa. When Dutch traders brought them home to Europe in the 1600s, they reminded people of the geraniums native to the area. The new ‘geranium’ was not winter hardy and had irregular flowers rather than the native plant’s five petals and perennial nature.
So we left the new plants in the same family as native geraniums but gave them the genus Pelargonium and kept growing them. But we still cannot stop calling them geraniums.
The pink plant on the left with a warm weather life and irregular petals is a Pelargonium, native to South Africa, but we call it a geranium simply out of habit.
The purple plant on the right is a hardy perennial native to Europe, it has five petals, and we call it Geranium because it is!
This plant is a good reason to learn botanical Latin!
So remember, geraniums are a genus of perennial plants, and pelargoniums are a genus of warm-weather annual plants that we call geraniums!
As sources of constant and complete garden color, nothing beats impatiens. The plant is compact, dense, mounded and the blooms, relative to the plant size are large. The branching of the stems is full and dense resulting in a high percentage of bloom to foliage. The foliage, elongated and ovate to elliptical are glossy with serated edges.
The plant produces the wall of color impact that we desire from annual bedding plants. They have the colorful impact in beds, borders and any kind of container and are an essentially low maintenance option.
As such, when the climate allows they are my first choice for color plantings. However, think of impatiens as real estate. Location is everything. In northern gardens we used them gladly all summer long until that first night of frost took them from the garden.
In a garden about 170 miles from this one and a hardiness Zone away they lasted for two to three years. They reached a height almost waist high covering the bed completely and requiring no weeding. (There is no gardener who does not appreciate a bed that goes for a year or more without weeding!)
In our present garden we plant them in quantity in October and by June they are essentially gone. If your summer location is kind to Impatiens, use them!
To increase you summer usage, plant sun loving versions, use partial rather than full sun locations and water and feed on a regular basis.
Summary-Your Best Heat Tolerant Annuals for the ‘Dog Days ‘
Attention and good maintenance are important to success in the ‘dog days’ of summer, but some plants are simply better at tolerating sun and heat exposure than others. The right plant selection choices, along with daily attention, will enhance the growth of your garden and the survival of your plants.
The most important things I have learned about keeping annuals in bloom all summer long are:
- Select only plants and varieties or cultivars proven to be resilient to known pests and diseases of heat and humidity. (Varieties are naturally occurring plant types, cultivars are created in greenhouses to improve our growing experience.)
- Assume that pests and diseases come with the season. Be proactive; look for changes that signal trouble when it first starts. This is Integrated Pest Management, and it is our best defense.
- Assume that heat and wind will dry soil far more quickly than in other seasons. Water proactively.
- Expect that fertilizer, even the timed-release variety, will wash through plants quickly.
- Control weeds, preserve water, and maintain temperature by using organic mulch.
“A garden is a grand teacher,
It teaches patience and careful watchfulness, it teaches industry
and thrift, above all it teaches entire trust.”-Gertrude Jekyll
Some Resources you can use:
“Latin For Gardeners, How To Read And Remember Plant Names”-some help with using Binomial Nomenclature to identify plants.
“How To Blend Annual Bedding Plants Into The Garden“-With links to annuals we grow.
Gardening With Annuals in Florida/University Of Florida– Note the useful charts at the end.