Focus on Flowers

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.

Red Hot Pokers belong to the genus Kniphofia (Kniphofia uvaria) and are also known as tritoma or torch lilies. 
Some dwarf varieties are 'mango popsicle', 'pineapple popsicle', and 'red hot popsicle'. They are orange, yellow, and red with grassy foliage. 
They spread by rhizomes and can become invasive. 
Native to South Africa, they like full sun and well-drained soil and do well in zones 6 through 9, as they tolerate heat and drought and dislike boggy soil. 
Flowers fade first at the bottoms of the torch-shaped blooms, but the striking blooms last a long time on the plants. After the blooming is over, do not cut down the foliage until it yellows and dies back in the fall. 
These are not flowering plants to put in pots or urns, as they look best in clumps and swathes in garden beds. Their vertical shape and vibrant orange, red, and yellow blooms make a strong statement. Give them room to spread and do not combine them with small plants that they will overwhelm. 
They are interesting perennials that have become popular on both sides of the Atlantic. While they do not combine well with cottage garden plants, they do create a modern looking presence and are perfect near a mid-century modern home.

Dianthus are well-behaved in our gardens. The flowers are fragrant, and the plants can be perennial, biennial, or annual. The common name "pinks” does not refer to the color but to the fringed edging of the petals that makes them look as if they had been cut with pinking shears. 
They like full sun but can manage some shade and a variety of soils. However, they do best in well-drained soil with good air circulation, as they are susceptible to root rot and fungal diseases. Rabbits eat the narrow grey/green leaves, but thankfully deer leave these plants alone. 
There are over 27,000 registered cultivar names, so there are plenty to choose from. Colors can be pink, lilac, purple, white, and combinations with picotee edging on the petals. They originated in Eurasian countries and are grown worldwide in home gardens because they are easy care and don't mind periods of dry weather. Dead heading keeps them looking attractive and the plants stay low. 
The flowers make sweet little arrangements and even just a few, in a small bottle, look pretty. I would not be without these plants in my Midwestern garden. Most varieties are not especially long lived, however, but that is okay as then one can always be tempted to try new varieties that come on the market. 
Common names are cheddar pinks, clove pinks, maiden pinks, and gillyflowers.

In the lower Midwest, May is the month when we see lots of white flowers. For example, Spirea ‘Bridal Wreath’ shrubs completely cover themselves with lacy white blossoms so that they do, in fact, resemble brides in traditional wedding gowns. 
The low-growing perennial iberis, commonly known as candytuft, also has lacy white flowers, and there are white lilacs and dogwoods in abundance too. Dogwood trees are positively dazzling when they are in full bloom. There is even a rare white double flowered dogwood Cornus Florida ‘plena.’   
Other white flowering trees include Bradford pears, serviceberries, and star magnolias. The kalmia shrubs, our native mountain laurels, have some whites, and the miniature white variety ‘Elf’ is especially lovely. The mock oranges are fragrant as well as white, and Philadelphus ‘Virginal” has luscious double blossoms. 
A dainty white flowering groundcover is sweet woodruff (gallium odoratum), and it has a scent like vanilla and has been traditionally used as a May Day centerpiece for celebrations. If you want to use this shade lover as a centerpiece, dig up several small clumps of it in bud and pop them into a basket lined with foil. They will happily bloom indoors and then can be replanted back into the garden. 
Lily-of- the-Valley is usually in bloom in the lower Mid-West on Kentucky Derby day and so make perfect centerpieces for Derby Parties. They smell wonderfully fragrant and partner well with mint juleps.

The common European marigold, (like the Mexican variety), is justly popular because it is easy to grow, and pests don't like it. It was first mentioned by the old-time herbalists in 1578, quote, "It has pleasant and bright shining yellow and orange single-petal flowers." 
It was used by herbalists during the times of ancient plagues, and the petals of the flowers were dried and sold for use in making broth in the winter. The flowers have also been used to add yellow color to cheese in times past.
Native to southern Europe, the seeds can be sown directly into the soil and germinate easily in sun or part sun. Plants begin to flower in June and continue till frost. Gather seeds when they ripen in August and September.
Some people use the flowers to treat the stings of wasps and bees and also to treat warts. Large flowering marigolds (those that originated in Mexico) are usually yellow or orange, and French marigolds are smaller and orange/brown in color.
All types of marigolds last well as cut flowers, but it is best to remove all of the leaves below the water line in a vase as they otherwise develop an unpleasant odor.
Marigolds are excellent plants for children to grow when they begin gardening as they are likely to grow well even with sporadic watering.
Note: 
The European variety (about 20 species) is daisy-like in appearance, and the botanical name is Calendula officinalis with the common name of Pot marigold or English marigold. The name calendula comes from the same root as the word "calendar," signifying that it blooms almost all year in zones 6-10.
The Mexican variety is larger and many petaled, and its botanical name is Tagetes, and they are unrelated to the European varieties.