The lettuce tasted bitter. The lilac didn’t bloom. The tomatoes rotted. The new bushes died in two years. The deer ate the arborvitae. The Million Bells fizzled. The rhododendron leaves turned yellow.

This litany might be heard on any given morning on the Master Gardener hotline, or at the front desk at a garden center, as frustrated gardeners look for whom to blame. After the complaints are aired, one of two conclusions often follows: “I’m giving up; I just don’t have a green thumb.” Or “Something was wrong with those plants.”

Both conclusions are flawed. About the “green thumb”: The people whose gardens thrive are people who either work very hard at it, have a lot of horticultural knowledge – whether acquired by experience, reading or instruction – or have excellent soil. Usually all three factors turned their thumbs green.

Next, how often does a consumer buy a truly flawed plant? Rarely. Yes, some plants that go home with you are healthier than others. One professional nursery or landscaper may have cared for them better than another, but most of those plants are perfectly viable. And occasionally a healthy-looking plant fools everybody because a virus, fungus or insect eggs were lurking in the soil, only to wreck your garden dreams a few weeks later. (Last summer’s plague of dying Impatiens, due to a disease affecting the whole industry, is that unusual example. The flaw, the disease, was in the plants, and it was not your fault, nor the fault of the grower or seller.)

A gardener’s confession

Recently I prepared for a Garden Writers Association workshop, aimed at improving our speaking and writing skills, and the homework was this: Name three gardening failures that were your own fault.

I could name 20, although I stopped at 10, too despondent to continue.

The good news is that gardening failures are usually lessons, if we accept that we made some mistake. Every master gardener or CNLP in training hears that “most plant problems are cultural,” not caused by disease or pests. Usually they say, “95 percent cultural.”

The instructor then explains that we must choose the right plant for the site and the soil, and we must plant and care for it correctly. While diseases, insects or weather surprises occasionally kill a healthy plant, plants become stressed, weakened or die usually because of cultural conditions (soil, drainage, watering, sunlight or weather). It’s more comfortable to blame the “bad plant,” or the seller, but honestly: The mistakes were mine. I missed something. I did something wrong.

As Pogo stated decades ago: “We have met the enemy, and he is us.”

Bitter lettuce, dying shrubs

Looking back at the litany of common gardening disappointments, patterns emerge. Gardeners make predictable mistakes in a few basic categories.

Timing: Sometimes it’s not how you plant, prune, water or fertilize, it’s when. In the vegetable garden, some crops grow well only in cool weather, such as peas, lettuce, spinach and broccoli. Lettuce turns bitter when the weather gets hot. On the other hand, warm-weather crops (tomatoes, squash, beans) develop many problems and don’t grow well until the soil is warm.

In the landscape, the timing of pruning – whether perennials, vines or woody plants – can make all the difference in whether the plant flowers, fruits or even survives the winter. (The lilac, mentioned earlier, didn’t bloom if you pruned it in September.)

Effective fertilizing and watering also require a sense of timing. Fertilize the lawn in late spring or early fall, but not in the heat of summer. Water the roses early in the day and don’t wet the leaves in the evening. As you plan a garden and learn what to do, always ask “When?”

Soil: What happens underground is invisible, so we tend to underestimate it. Yet soil has everything to do with plant health and survival. Those rhododendrons turned yellow because the roots can’t absorb enough iron, because the necessary mycorrhizae can’t live in your alkaline soil. Plant a rhododendron in acidic soil; you’ll see green leaves. The lesson: Find out your soil’s pH before big landscape purchases and make a good soil-to-plant match. Similarly, some plants require organic (compost-y), well-drained soil and they will die if the roots get waterlogged. Other plants absolutely thrive in poorly drained soil. Match plants to soil.

Water: Watering poorly or insufficiently is a major reason for plant death. Those “bushes” (properly termed “shrubs”) that failed are most likely to have died from insufficient water during their first one to three years in the ground. Homeowners commonly water a new tree or shrub with great enthusiasm for a couple of weeks, and then think it’s fine on its own.

The truth is a recently planted tree or shrub might need five to 10 or more gallons a week for the whole first and second growing season (and a good effort in the following years during dry periods).

The frequency of watering also makes a vital difference: The container plant in the sun must get water daily, but the established lawn or young spruce would do better with deep, infrequent watering – not daily.

Weather, critters and the rest: Now, you might ask, how can I say that the deer eating your arborvitae, or the ice storm cracking the bird’s nest spruce, is your fault?

We set ourselves up for plant problems because we make poor plant choices or place them poorly. If you have deer around, they are guaranteed to eat Arborvitae, hostas, yews and Euonymus. The little spruce right under the eve, where the snow dumps, will crack. The Japanese maple on the windy side of the house may get winter burn, but would do fine with some protection. Location, location, location.

All this may sound discouraging, as if there is so much to know and it’s all so complicated. But plant by plant, it’s not that difficult: Match the plant to the site and learn what to do for it (and when to do it). Someday your thumb will also turn green.

Sally Cunningham is a garden writer, lecturer and consultant