Maria is a master gardener and master of public health. She & her husband, known online as The Gardener & The Cook, live in coastal Alabama.
Annuals for Your Sun Garden
This article began as "Sun-Loving Flowers" with both annuals and perennials, but it quickly grew far too long. So I have divided it into two articles: one for annuals and one for perennials.
There are more sun-loving annuals than can be covered in one article, so this article will discuss some of the most popular and easy to grow species. Most annuals re-seed themselves, particularly marigolds, zinnias, petunias, celosia, and vinca.
Annuals Have Two Main Purposes in Life
We tend to think their only purpose is to provide us with beautiful flowers for our enjoyment. While they do that, it is not their main purpose.
- They provide food for the pollinators, who then pollinate our food crops.
- They produce flowers so they can die and produce seed for next year’s flowers, and the process is repeated annually.
The common zinnia (Zinnia elegans) has become one of my favorite summer flowers. They are available in a multitude of colors and color combinations, from deep, rich hues to delicately pale hues. All make a massive splash of color in the garden, and they make great cut flowers. They bloom heavily, and continue blooming until the first hard frost.
They were once considered an old-fashioned plant, but over the last few years, they have become one of the most popular annuals around. They are so easy to grow, and drop their seeds for next season, it’s no wonder they have skyrocketed in popularity.
Types of Zinnias
There are three main types of zinnia blossoms: single, double, and semi-double. The distinction between these is dictated by the number of rows of petals, and whether the center of the flower is visible. It is the visible centers that attract the pollinators.
- Single have a single row of petals and a visible center.
- Double have multiple rows of petals which hide their centers.
- Semi-double have numerous rows of petals, and visible centers.
When and Where to Plant
While you can start seeds indoors, then transplant, Zinnia seeds can be sown directly in the ground when the daytime temperature is at least 60°F (16°C). Germination will probably not occur until the soil has warmed to at least 74–84°F (23–28°C).
The taller varieties are best placed in the background of a garden bed, with the smaller varieties in front, or along a border in front of other plants.
Snapdragons are probably my favorite winter flower. They are included in a group known as "cool season crops", but are not edible, as pansies are.
Snapdragons will bloom prolifically beginning in autumn and lasting until hot weather arrives. They re-seed themselves readily, so after a year or two of planting them, you should not have to buy more — just wait for those dropped seeds from the previous season to germinate.
Diamond Frost (Euphorbia hypericifolia) looks so delicate, but it will surprise you. It is actually tough as nails. It performs well most anywhere. It does best in sun or part sun, but also does surprisingly well in light shade, too. What's more, it is extremely heat tolerant. The only downside for me is that it is cold hardy only in Zones 10a through 11b. So, mine will probably be killed this winter here in Zone 8a unless, of course, I pot it and take it indoors for the winter.
While Diamond Frost has very few needs, and seems to be fairly self-sufficient. Still, as with all plants, an application of either compost or fertilizer will have it performing at its best.
The photo above is of one I have grown from a tiny cutting given to me by a friend that I rooted back in April. Now I'm ready to take more cuttings to create more plants. It adds a nice touch to containers when planted with other flowers, but also looks beautiful planted alone, whether in a container, or in your landscape. The common name of Diamond Frost is actually a trade name by Proven Winners.
Diamond Frost is in the spurge family (Euphorbiaceae), and like its many cousins (poinsettia is one of them) it bleeds a white, milky sap when cut. The sap is a form of latex, so if you have latex allergies, you may want to wear protective gloves when working with Diamond Frost. Plants in the spurge family often will bleed a milky, white sap if cut or wounded. This sap is a form of latex. Most people will have little or no reaction due to sap exposure from the euphorbia that Proven Winners sells. However, people with sensitive skin or latex allergies should be cautious when handling euphorbia. Poinsettias are in this same family. If you have ever experienced a skin irritation due to contact with poinsettias you should be cautious with all euphorbia.
Diamond Frost is an annual except in Zones 10a through 11b, where it is said to be cold hardy.
Marigolds have flowerheads that resemble either daisies or carnations that are produced singly or in clusters. There are over 50 species, but most marigolds in the typical garden are one of the following:
- Tagetes erecta: Native to Mexico and Central America, these are the tallest and most upright marigold. They can reach up to 3 to 4 feet in height and produce large, full flowers. They are drought-tolerant.
- Tagetes patula: This species is often called French marigolds. They tend to be smaller, bushier, and compact. They are often wider than they are tall. They are eye-catching and elegant, and grow anywhere from 6 inches to 2 feet tall, depending on the cultivar you choose. They are better suited to rainier conditions than the other Tagetes species.
- Tagetes tenuifolia: These very petite marigolds thrive in hot, dry sites, and make wonderful edging plants. It is rare for these to reach more than a foot in height.
- Calendula officinalis: This one is not a true marigold, but it is the one our ancestors called marigolds and used as medicinal plants. It is often grown in herb gardens for its peppery taste.
Where to Plant Marigolds
Marigolds need full sun and well-drained soil. If planted in either shade or cool, moist soil, they will be prone to powdery mildew, and will not bloom well. When I was very young, I planted marigold seeds under a large oak tree. They came up, then died within a month.
How to Care for Your Marigolds
- After marigolds have established themselves, they can be encouraged to grow bushier by pinching off the tops of the plants. This will prevent them from becoming leggy and will also encourage more flowering.
- Deadheading is not required, but if dying blossoms are removed on a regular basis, the plants will continue blooming profusely.
- When watering marigolds, allow the soil to dry somewhat between waterings, then water well.
- Do not water marigolds from overhead. Water at the base of the plant because excess water on the leaves can lead to powdery mildew.
- Withhold fertilizer during growth. Too much nitrogen stimulates lush foliage at the expense of flowers.
The Many Faces of Vinca
There is vinca, and there is periwinkle. They are in the same botanical family, Apocynaceae, but their flowers have different arrangements of petals. Both are great at re-seeding themselves – almost to the point of being invasive. On the other hand, they add beauty to the summer garden, they can take the heat, and they last until freezing temperatures arrive. Want more for next year? Don’t worry. They will more than drop enough seed for next season, and each season to come.
I have them in my garden every year, as they grow quickly, and cover any bare spots I may have. They are available in pale pink, hot pink, red, purple, white, salmon, and some with a different color center, as shown in the photo above.
Is It Vinca or Is It Periwinkle?
The ones I call vinca are more mounding and spreading with a close arrangement of petals. The ones I call periwinkle are more upright, and the petals have spaces between them. Both are shown in the next photo. About three years ago I ordered vinca seed from Amazon, and what I got was periwinkle seed — which I did not like. So when I find these in my garden, I pull them up and trash them. There is also a vining type, but I do not have it.
Periwinkle vs. Vinca
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2022 MariaMontgomery