August is a good month to assess what went right and what not so right in the garden. Most perennials have matured to their full size, lawns problems are easy to spot, and trees can be easily evaluated for signs of stress and future pruning.

My lawn has been healthy and green all summer, thanks to adequate -- though not excessive -- rains. I have more troublesome broadleaf weeds in my lawn than previous years. Biggest invaders are dandelions, yellow wood sorrel and plantain. I am hopeful that the lawn fertilizer I just applied will stimulate turf growth and crowd out some of the broadleaf weeds.

Incidentally, this is the best time of year to fertilize lawns. University of Minnesota turfgrass research shows that late summer and fall are the optimal times to fertilize lawns. Early spring applications of nitrogen cause a surge of top growth in the plants, the research shows, which makes the lawn look nice in the spring but depletes the plants’ energy reserves. Consequently, when summer stress periods occur, plants are weaker and less able to survive.

By applying fertilizer in late October or early November, when top growth is minimal but when soil temperatures are still warm enough for nitrogen absorption, plants resume growth and green up early the following spring without the excessive shoot growth associated with early spring nitrogen applications. The ideal situation for fertilizing a lawn is a cool day when rainfall is predicted or watering can take place immediately following the application.

I am guilty of one of horticulture’s unpardonable sins: careless driving of the lawnmower. Last week I steered my walk-behind mower too close to the trunk of a 4-inch diameter Japanese tree lilac tree and scraped off a 2-inch patch of bark several inches above the ground. Shame on me. Gashes from lawnmowers and weed whips cause needless injuries to trees that are slow to heal and invite invasion of insects and disease.                    

Not all of the annual flowers that I started from seed last winter and grew under lights for transplanting warrant repeat planting next year. Several annuals that performed beautifully this year include ‘Black Velvet Rose’ geranium (transplanted in containers, in full sun); and ‘Dragon Wings’ begonia (containers, partial shade). Begonia seeds are tiny, need to be planted in late January or early February, and never germinate 100%. These shortcomings are worth the challenge thanks to the dazzling, summer-long red begonia flowers that are superior to the blooms of generic begonias purchased off the shelf.

I won’t start anymore ‘Wizard Mix’ coleus seeds. After transplanting to containers in late May, the plants stalled out and didn’t begin growing vigorously until mid- to late-July. It may be the soil mix I am using that accounts for the slow start. If I order coleus seed again, I will experiment with newer varieties such as ‘Black Dragon’ or ‘Palisandra.’

I really like an annual dichondra variety called ‘Emerald Falls.’ The 1/2-inch-diameter round leaves of this plant trail over the edge of hanging pots and make a nice accent for begonias and other blooming annuals.

I had high hopes last May when I brought home three Endless Summer hydrangeas. One bloomed early, nearly blue, and then failed to produce any new blossoms. Another plant a few feet away hasn’t bloomed at all but got a slow start after some critter dug it completely out the ground a month after planting and I had to re-plant it. A lot of weird stuff goes on in the garden at night.

At the advice of Tom at Chaska Farm & Garden, I planted a third Endless Summer in a half-barrel planter and it has produced vigorous foliage but so far no flower blossoms. I am getting concerned that it won’t bloom before frost, or if it does, it will only show off its full blooms for a couple of days before our predicted early frost. I have fertilized this hydrangea with an acid fertilizer and am curious to see if it produces blue flowers. It will also be a test to see if it over-winters in the wood planter. Endless Summer hydrangea is hardy in Zone 4 in the ground but may be more susceptible to winter loss in a container.