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Earlier this year I wrote about a highly recommended viburnum that I had planted as a specimen on a bank maybe six years ago and again two years ago to finish another round of landscaping in front of my house. By two years ago I had figured out that to get a good crop of berries you needed to add a different cultivar of the same species for pollination.

By last year I had found an unheralded member of the same species from the original plantings, which I planted, at either end of the row in front of my house. The experts were right; I got more berries.

The unheralded one-year-olds are bending to the ground with berries, while the recommended variety shows only a slight improvement in berry crop. I fear that I have just encountered surprise number 4307 in my efforts to learn about gardening.

The last three paragraphs hopefully suggest that some plants need a pollinator to successfully bear much fruit. The other two options in fruit or seed production are plants that self-pollinate and those that need specific male and female plants.

I think I am safe when I say that the vast majority of plants are self-fertile and can produce fruit (seed) when pollen (male part) is moved to the female parts of the flower on the same plant. This can be done by insects or even by the wind. Our common flowers have both the male and female parts in the same flower.

Insects can move pollen between different flowers on the same plant or for that matter between flowers of different plants. For that reason you may see differences between plants that just come up in your garden from reseeding. Commercially available seeds today are usually F1, or first-generation, hybrids and will produce very uniform plants.

Most conifers (evergreens) have separate male and female reproductive bodies and use wind to create the pollination. Since wind normally swirls up, the male flowers are usually at the bottom of the tree and the female flowers that produce the cones are closer to the top.

When we started, we were talking about plants that took two different members of the same species to produce the best crops of fruit. Multi-seeded fruits like apples and pears need this. So do some pitted fruit like sweet cherries and plums. Plums can be very specific about who pollinates whom. Peaches and nectarines are self-fertile.

In the shrubs, we have already identified viburnums as needing two different plants of the same species for good berry crops.

The other group, dioecious, meaning "two house", requires specific male and female plants to make seeded fruit. In this group, only the female will show fruit. Hollies are the most recognized members of this group. There are others. Fortunately, one male can be hardly noticed hidden in a group of females. Generally, real close proximity is not an issue.

Gardening is one continuous learning experience complete with surprises. 4307 was just a guess, but I am sure I will be claiming 5000 before long.

One evening last week the lawnmower and I raced around the end of a large shrub border only to be stopped in our traps by the sweet fragrance wafting from a small patch of clethra or summersweet on the downhill side of the border.

They have been there for at least five years and had never really created much excitement. The problem is that even the downhill side of that hillside border is on the dry side. This year they are happy.

In other words, clethra is a wonderfully fragrant summer blooming native shrub that is happiest in a rather moist site.

It grows well in sun or light shade and does not seem to be picky about soil as long as it is moist. I have seen a wee bit of winter tip kill but I am guessing that they were more discouraged by their dry location, rather than being mad at our winters.

A white form is normally seen. The two most common varieties are called 'Hummingbird' and 'Sixteen Candles'. The latter is supposed to have a better form than 'Hummingbird' and is a bit shorter. 'Sixteen Candles' is listed to have a height of 28 inches. I'm thinking a little bit bigger.

There are two red/pink forms also. They are 'Rosea' and 'Ruby Spice'. I'm not sure I would be able to tell the difference if you showed them to me in the garden. The pink/red ones seem to be significantly taller than the white forms. All varieties show yellow fall foliage.

It is a multi-stemmed shrub that will produce a clump that will slowly expand.

The clethra are happy now, but as in every season the weather plays a large role in identifying the WOW plants from the so-so ones. It would be easy to guess that some of the tropicals that we grow as annuals are longing for more heat.

Another plant that may play tricks on us this year is the garden mum. They way they are commercially grown in this area uses our natural temperature to determine bloom time.

In an extremely hot summer it is often difficult to find a lot of blooming by fall fair time. This year with the other extreme we may see a lot of summer rather than fall mums.

If yours in the garden are budded ahead of time you have the same two choices the commercial growers have. Let them bloom early or remove the current buds and risk mums blooming later than we want.

In the garden we live by the weather. There will be winners and a few losers each year but you have to wait to the end of the gardening season to decide which is which.

One of the colorful additions to the mid-summer garden is the large flowering hibiscus. Although plant height ranges from just below my waist to a wee bit over my head, depending on variety, it dies back to the ground each winter.

If you are growing it, mark its spot in the garden. It joins a short list of common garden plants, like butterfly weed, vitex and crape myrtles that meet untimely deaths because people are impatient for them to wake up in the spring.

The large-flowered hibiscus normally sleeps until mid-May and I have frequently seen specimens not showing new growth until early June. I let the dead stems stand until I see action in the spring.

Once the plant is growing, it comes on like gangbusters. For best results, I suggest tipping the fast growing multiple stems that emerge when they reach 15 to 20 inches in height. That causes branching and can produce some incredible blooming machines by mid-July into August.

For the tall ones, I favor the old timers. 'Lord Baltimore' is a cut-leaf brilliant red. 'Lady Baltimore' is a strong pink. 'Copper King' has a mahogany leaf and a bicolor pink flower with a darker center. There is a long list of other tall ones that I have seen/tried and I keep coming back to the old standards.

The near waist-high group is a different story. Many have been ok, but some recent introductions have flopped. In the last several years a series named after French wines have been introduced. After two years of observation, they appear to be the answer.

Give the plant full or near full sun in soil that is average or on the moist side. I have seen moisture stress in some of our driest summers in high spots.

Recently, a specimen of 'Lord Baltimore' was spotted growing from a pot submerged in one of the lily ponds at Longwood Gardens. I still haven't determined whether it was a permanent fixture or a short-term addition that will be rescued from drowning after a few weeks.

Hibiscus do attract Japanese beetles, but they seem to be rather scarce this year. I am keeping my fingers crossed. I had problems with another beetle three or four years ago, but generally they seem easy to grow and appear rather pest free.

Single flowers often exceed seven inches across and last for several days. They also are hummingbird targets.

If you appriciate the plant and its late emergence, it makes an excellent summer specimen for many gardens who are starting to fade after the spring flourish.

Picutred above right Hibiscus 'Pinot Grigio' new vintage series of medium height hibiscus. Middle left: Old time favorite 'Lord Baltimore'. Below right beautiful cut burgundy foliage of 'Kopper King'.

I remember when life was simple. Purple coneflowers were purple. Sure, occasionally you got a seed with recessive genes and it was white. If you planted the white one away from the purple one you could have white ones. If you planted it with the purple ones the recessive gene soon gave way to the purples and the white ones were gone.

Then maybe fifteen years ago some breeders/researchers decided that maybe they could work magic with Echinacea. Scouring the country, they found 11 different species of coneflowers. Most came from western (drier) soils, rather light low fertility soils with excellent drainage and soils with generally high pH.

If you take that last sentence to the garden, I would expect your happiness with coneflowers to increase.

Traditionally, we had the species Echinacea purpurea or selections of it in our gardens. The researches found three additional species: paradoxa (yellow), pallida (pink) and tennessensis (petal arrangement) that held promise in the garden. These can be grown from seed and thus should be relatively less expensive than the new hybrids.

After that, the fun or folly set in. My guess is that it has been mostly fun. A look at plant catalogs and one could make a list of Echinacea cultivars that would use your fingers and toes multiple times.

You can find red, orange, white, yellow and of course purple. You can find straight petals, over-lapping petals, drooping petals, narrow petals, wide petals and a few that have lost their way and look like zinnias or dahlias. Technically, they are rays not petals. But most of us will continue to call them petals. The current focus of research is on double or tubular rays now. They are coming.

Some are fragrant but my old sniffer often has problems with that claim.

If there is any folly it is that sometimes plants, including Echinaceas, get rushed to the market and the question gardeners must answer is, are they stable and really perennial? To me it seems that there is a correlation between poor quality and the amount of magazine and advertising hype a plant gets. I hope I'm wrong.

In spring 2008, I planted ten of a hybrid yellow one in front of my house. They flopped a bit but were fine. This year I have seven yellow ones, two purple ones and one of the best white plants I have ever seen. Of course there were purple ones in the immediate area,I had near complete success and stability when I planted the hybrids away from the purple ones and the opposite when I planted them together.

Coneflowers will get aster yellows (spread by a certain leafhopper) and wilt. Aster yellows will distort flowers and growth and create a green freak. Wilt is like it sounds, the plant wilts and dies for no good reason. I have never seen yellows and seldom see wilt in a mixed garden.

This article idea started when I heard one of the prominent Echinacea breeders speak while visiting an Echinacea trial. The trial was on a level stretch of heavy clay soil, a history of high fertility, mulched well and the previous use was an aster garden for cut flowers. If you suspect there would be some problems you were right.

Photo IDs: Top left Echinacea tenneseensis. Middle right Echinacea paradoxa. Bottom left Echinacea 'Tiki Torch'.

My neighbor has a beautiful hydrangea bush. It's lush and full and...green. No flowers. We'll come back to this in a bit.

There are four main types of hydrangeas. Two are native to North America. Two are found in Asia.

The first native hydrangeas to bloom are the snowball type, Hydrangea arborescens. This is your grandmother's snowball bush. It likes morning sun, but shade in the hot afternoons. This hydrangea can and should be cut down to about one foot every year. New breeding has strengthened the stems and enlarged the flowers. These are easy to grow.

The oakleaf hydrangeas are the second native type. Hydrangea quercifolia is one of my top 5 shrubs. They're fantastic. They prefer part sun, have lovely large cream blossoms, that fade to pink and dry well. All in all you can have large blooms for several months. In the fall, the foliage has a nice red color. Ornamental bark provides yet another season of interest. It is also fairly foolproof. The oakleaf hydrangeas bloom on old wood, so do not prune after August, or you will cut off next ears flowers.

Hydrangea paniculata is the only hydrangea that can be trained into a tree form. It is originally from Asia. The flowers are cones rather than big balls. 'Limelight' and 'PeeGee' are common cultivars on the market. They like a bit more sun, and also bloom on "new wood". This means they can be pruned anytime except in the summer just before they bloom. They get fairly large, so give them some space.

The most finicky, but some argue the most beautiful, are the other Asian types, the mopheads and lacecaps, Hydrangea macrophylla. These are the ones that bloom in various shades of blue or pink. The color is largely due to pH. A more acidic soil gives a blue color, a more basic pH (above 7) gives shades of pink. If you want a bluer flower, add sulfur. If you want pink, add lime to your soil.

These hydrangeas set their flower buds the previous summer. In other words they bloom on "old wood". If you prune them in the fall, or we have a cold winter that freezes the tips- you've lost the flowers. This is the cause of my neighbor's green bush.

If you search the internet, there are elaborate methods describing how to protect them from damage. They involve chicken wire, leaf litter, some plastic sheeting, etc.

Luckily, there is a lot of current breeding to improve the cold hardiness of this type of hydrangea, as well as making the bloom on "new wood", or this seasons's growth. The first and best known variety is 'Endless Summer'. 'All Summer Beauty' is another of this type. As I look to the future, I see many more varieties in the pipeline, which bloom and rebloom on old and new wood.

A word of advice, if it comes wrapped in foil from the florist, you can bet it won't be hardy.

There are two types of vining hydrangeas. The true hydrangea vines(Hydrangea anomala subspecies petiolaris) are vigorous climbers, but don't like to bloom. If you want a climber, that actually blooms, try Schizophragma hydrangeanoides, false hydrangea vine. My parents have this growing up the side of their deck and it is gorgeous.

Hydrangeas are the queens of the summer blooming shrub border.If you have space, they're worth a try.

Photo ids: Top left Hydrangea arborescens 'Annabelle'. Middle Hydrangea paniculata in tree form. Lower left Schizophragma hydrangeanoides on Groff's deck.