Focus on Flowers

Canna comes from the Greek word spelled "kanna," which means "reed," though the canna plant does not have narrow reed-like leaves. 
There are about 10 species in the genus, which has showy flowering plants that grow from tender rhizomes that can only be left in the ground over winter in zones 7-10. In other zones they must be dug and stored over the winter. 
Canna plants enjoy moist but well-drained soils in full sun. Plant the rhizomes 4-6 inches deep and space them 18-24 inches apart for best results. They can also be grown in large pots and stored in the pots in areas where the winter temperatures remain above 40F degrees. 
If dug for storage, do this after the first frost and store the rhizomes in vermiculite. The rhizomes can then be divided and replanted in the spring. If they shrivel during winter storage, spray lightly with water occasionally. 
Plants can be grouped and used to provide height and dramatic effect, in beds and borders, or used to conceal a fence or shed. When bloom is finished, cut the flower stalk right down. If you grow and enjoy these bold, showy plants, you will soon have a lot, as the rhizomes increase quickly. The original bright reds, yellows, and oranges, as well as the newer shades, pack quite a punch in the garden in high summer.

The common evening primrose is native to Virginia and was sent to England in the early 1600s, feeling quite at home there and has naturalized in several parts of Britain. 
The Missouri primrose was identified first in 1811. 
The evening primrose has both roots and leaves that are edible. The roots are sometimes eaten in France and some herbalists believed that the plant can be used medicinally for asthma and whooping cough. 
The botanical name for evening primrose, Oenothera, is from the Greek, which is interesting since all members of this plant family are natives of the New World. 
Oenothera fruticosa is hardy zones 3-8 and blooms in late spring, and its common name is sundrops. The nectar attracts butterflies and hummingbirds, and it grows 12-24 inches high. 
The pink evening primrose is Oenothera speciosa, and the flowers open in the evening and close in the morning. The white form is called 'Alba'. 
The Missouri evening primrose 'Missouriensis' has lemon yellow flowers on low red stems. It blooms from May through August and enjoys a dry soil. 
Divide these plants in spring or fall. Sometimes these primroses are aggressive growers, especially the pink ones, but they also often die out after a while. They are popular pass-a-long plants and easy to grow and are fun.

Many of us are familiar with ageratum, the low-growing annual with fuzzy flowers that are blue/lavender color. It is a member of the Ageratum genus that includes 43 species of annuals and perennials, most of which are native to warmer regions of the American continents. 
They have felted oval or heart-shaped leaves and clustered flower heads. They like full sun and moist well-drained soil, and a common name is floss flower. Another common name is billy goat weed, which suggest perhaps that goats may like them. I am guessing about that, as I have never seen a goat eating ageratum in my garden. Of course, I do not have any goats in my garden, even though I do have ageratum, as it pairs well with just about any other plant of any color. 
I also grow tall varieties ‘Bavaria’ and ‘Blue Horizon’, which are 18-20 inches tall and produce good cut flowers that dry well. 
Some species of ageratum can be pink and white as well as blue. Some even grow in light shade—for example, Ageratum altissima, which gets quite tall and has fluffy white blossoms. 
Some native varieties of ageratum winter over in our zone 6 and may become a pest as they self-sow prolifically. As long as you just grow varieties of this plant that are annual in our cold climate, however, it is well behaved. Otherwise, you may need to get some goats!

Blue false indigo, with the botanical name Baptisia australis, is a lovely shrub that blooms in the late spring in zones 3-9 in full sun or part shade. It grows about 4 feet tall and as wide and is drought tolerant and deer resistant and has blue/green foliage and blue flowers that resemble lupins. 
It was used by pioneers to dye cloth and is called 'false indigo' because its color is not as deep as true indigo. It has a big root system that cannot be divided. However, it grows easily from seeds. Gather the dark-colored seed pods in the fall and start new plants any time. 
This plant has been hybridized so that there are now white, purple, and yellow flowering varieties available and some that are smaller. 
They prefer full sun and good drainage to bloom well and can be planted as a hedge or as a background plant. The foliage stays grey/green and crisp and neat until late fall when it can be cut to the ground. I have mine in the front of a large flower bed, but if I was planting it now, I would place it at the back of a bed, as its flowering period is short, and it tends to self sow. However, the foliage always looks cool even on the hottest day of summer.

Native to Mexico, dahlias probably grew in Aztec gardens as they were already in cultivation when the Spaniards arrived.
Francisco Hernandez, a botanist and physician to King Phillip of Spain, described them in a book published in 1651. But dahlias were not introduced to Europe until 1789 when seeds were sent from Mexico to the Royal Gardens in Madrid. The flower was named in honor of Dr. Dahl a Swedish botanist and pupil of Linnaeus. They were sent to Kew Gardens in England in 1798 by the wife of the British Ambassador to Madrid. 
By 1835, John Wedgewood, the founder of the British Horticultural Society, grew over 200 different varieties of dahlias. They were popular cut flowers with blooms of many sizes and colors. 
If a tuber has a sprout of more than 2" long, clip it off before you plant the tuber. Dig a hole 4-6 inches deep and place the tuber on its side and cover it with soil. Fertilizer is needed every 3-4 weeks and must be low in nitrogen. Do not water until sprouts are visible above the ground and then water deeply 3 times a week. Full sun is best, but plant in part shade if your temperatures go over 100F degrees. 
Dahlias bloom about 3 months after planting. Cut blooms that are 2/3 open and place the stems in hot (but not boiling) water in a plastic container and leave them in it until the water cools.