Occasionally gardeners want summer flowers that make a brave show and don't need pampering. They are especially useful in the distance, perhaps behind a low fence separating the area from the more intensively cultivated part of the garden proper.
One of the best American weeds is the cleome or spider flower. Given sun, water and good soil it grows to six feet with grapefruit-size clusters of magenta, pink or white flowers that bloom from July to frost. The white kind called 'Helen Campbell' is quite beautiful in dim light at night, though cleomes are increasingly offered only in mixed colors.
Some gardeners never get over a love of sunflowers. There are various kinds, some only chest high, while others reach eight or 10 feet. If you love them but feel uneasy because they are somewhat weedy, you can always justify planting them on grounds that cardinals, jays and many other birds are fond of the seeds. I often think the way to grow them is with great boldness, great masses of them, as if you really meant for them to be there and they didn't just spring up because you weeded carelessly.
A flower of stunning color is the tithonia, which grows very like a sunflower to perhaps six feet in height, but with flowers maybe five inches across, of intense vermilion. I cannot think of a flower more gorgeously colored. Sometimes beetles gnaw the leaves. Catalogues say the plants grow four feet, but I think you will find six feet or more is the height they reach in our admirable climate.
Cosmos can also reach six feet and have agreeable thready leaves, very light and delicate in effect. They are very good for late summer when most things look tired. They come in pastel colors and bright orange, and it is well to remember the basic color of the cosmos is magenta or rosy lilac if you prefer.
A plant everybody likes when it blooms, but which few gardeners get round to planting, is the moonflower, a vigorous climber reaching 20 feet or so in good ground, and offering saucer-size morning-glory-like blooms at night. They grow properly only in hot weather, and there is no point planting them before May. They can be brought to prodigious size with occasional doses of manure and plenty of water. They only open about 9 p.m., so don't count on them for early evening. They are scented. They are easily grown from seed, as all plants mentioned today are.
It often surprises me that people grow zinnias only in mixed colors. Of course if you like to have all the colors, that is the best way, but do not overlook the effect of large patches of huge white (dahlia-flowered) zinnias, especially if you sit in the garden mainly at night. Pale yellow ones also show up well. One year I had these big zinnias in white, yellow and lavender and found them rewarding. Like everything else, it is increasingly hard to find zinnias in separate colors, but some of the large houses like Burpee's still have them.
They require good soil, plenty of sun and water, and must be kept quite free of weeds when small, but once they gather steam they are trouble-free. This may be the place to point out the obvious, that the gorgeous scarlets look black in dim light and do not show up at all at night.
For bold tropical foliage hardly anything equals the canna. Two varieties that have bronze or purplish red foliage and red or red-orange flowers are 'Wyoming' and 'Red King Humbert,' both of them good growers. A clump of three or five plants will make rather a show. You can start the tubers indoors from now on or, much simpler, plant them directly where you want them any time after April 15.
The only marigolds I really like are the huge Sunset Giants types with flowers bigger than teacups. I know they are not very useful for most gardeners (or for me in my small garden) but once in a while it is good to get them out of your system. The plants are more than waist high sometimes, and sometimes they sprawl over, but no matter, they are gorgeous in a fine gross way when well grown. They are best given a patch of land all by themselves.
For good effect in the distance you might try planting 15 or 20 gladioluses in a circle 36 inches in diameter. If you use only one variety the effect is better than with mixed kinds. I have not tried gladioluses this way, but they are supposed to support each other and not go down in storms, and if they're at the end of the garden you wouldn't mind too much when they finished flowering.