Actually, French marigold, Tagetes patula, is no more French than African marigold is African. All are from Mexico and Guatemala. They were merely popularized and bred respectively in France and Africa. There are now hundreds of varieties. Yet, their color range is surprisingly limited to hues and shades of yellow, orange and ruddy brown. White marigolds are really just very pale yellow.
While African marigold is only occasionally grown for bigger cutting flowers on taller stems, French marigold is much more popularly grown for late warm season annual color. Because it blooms late in summer and early in autumn, and continues only until frost or sustained rain, it is often planted if earlier warm season annuals deteriorate while it is still too warm for cool season annuals.
French marigold can get more than a foot tall, and almost a foot wide, but typically stays closer to the ground. The delightfully aromatic and intricately textured foliage is rich dark green. Removal of deteriorating flowers (deadheading) promotes continued bloom, although a few spent flowers might be left to produce seed. Mildew can be a problem if watering is excessive or late in the day.
Like gardenia, dogwood and snapdragon, the potentially finicky Madagascar periwinkle, Catharanthus roseus, is often challenging to grow. It enjoys, but seems to prefer more humidity than it gets here. The happiest plants can get nearly two feet tall and wide in sheltered and humid spots. (They can get even larger in exposed spots in humid climates.) Yet, most of us are satisfied with relatively scrawny plants less than half a foot tall.
Oh, how breeding complicates things. Many years ago, there were only six basic types of wax begonia, Begonia semperflorens-cultorum, with three choices for floral color, and two choices for foliar color. Bloom was white, pink or red. Foliage was either green or dark bronze. Although these choices have not changed, some modern hybrids are difficult to distinguish from other species.
Just like African marigold that was featured earlier is actually Mexican, German primrose, Primula obconica, is actually Chinese. As odd as it is, the common name is an improvement from the former name of ‘poison primrose’, which was derived from the potentially irritating sap of the unimproved species before it was bred to be less toxic, as well as more colorful and prolific in bloom.
French Marigold might have been a more appropriate choice. It is the official flower of Dia de los Muertos on November 2. Some might say that the bigger and bolder African marigold, Tagetes erecta, is just as official. Both are Mexican, but as the names imply, most varieties of French marigold were developed in France, and most varieties of African marigold were developed in Africa.
The three most popular specie of Dianthus are sweet William, garden pink and carnation. Sweet William and garden pink are light duty perennial bedding plants that are often grown as annuals. Carnation blooms are more familiar as fragrant cut flowers than as home garden flowers. Then there is dwarf carnation, Dianthus caryophyllus, that combines the best characteristics of all three.
The common name sounds funny, but it is easier to pronounce then than the Latin name. Mulla mulla, Ptilotus exaltus, is an Australian species that has been locally available longer than its limited popularity suggests. It may seem to be more peculiar than it is because it is grown primarily by specialty growers, who happen to grow many cool plants that should be more popular than they are.
They are really just smaller versions of the larger perennial dahlias that are grown for their big bold flowers and flashy colors. Technically, annual dahlias produce smaller versions of the same perennial roots that can survive through winter to regenerate the following spring. Yet to most of us, it is easier to purchase new plants in spring than to grow new plants from stored roots.