12 Mistakes Master Gardeners Want You to Stop Making

In gardens large and small, there is no end to the ways you can express yourself, cultivate a beautiful landscape and, unfortunately, mess up. Every mistake in the garden is an opportunity to learn, and rarely does an error lead to tragedy. Still, the fewer missteps, the more we can enjoy all that our gardens have to offer.

Here, four Master Gardeners share the top mistakes they see among gardeners. Master Gardeners are volunteers who complete a horticultural-education program with their local Cooperative Extension. They are the go-to gardening experts in many communities.

Whether you’re growing vegetables or ornamentals, trees or herbs, this season’s assignment is to move past these 12 backyard blunders.

Planting Before Observing

Texas Master Gardner Keisha Johnson, aka Rural City Gurl, encourages others to observe their space before they make garden plans. This is an exercise in patience as you delay your garden while you learn about your property, whether that's a patio or a full yard.

“Orient your space in terms of sun/shade exposure. This will help you decide the types of plants that will thrive and grow in particular areas,” she says.

Keisha points out fences, buildings, trees and other plants affect your patchwork of sun and shade. The way the shadows move changes throughout the seasons, as well.

Watch rainfall's movements across your property, how wildlife come and go and the direction of the wind to learn even more about the best spots for the plants you want to grow.

According to Virginia Cooperative Extension Master Gardener Lynda Ramirez-Blust, who is also the lead gardener for Arlington House Kitchen Garden at Arlington National Cemetery, this mistake happens all the time.

“I have to consciously restrain myself from going into people's yards and fixing the mulch around the base of their trees,” she says with a laugh.

Lynda wants gardeners to stop “volcano mulching” their trees, piling up a mound of mulch up to and around the tree trunk, for several reasons: “It makes it harder for the soil oxygen to get to the roots, because it just means your roots are that much deeper into the ground. You end up watering the mulch, and it never soaks down into the soil, so it never actually gets to the tree, or the tree roots start to grow into the mulch, and then the mulch dries out and those roots dry out. And [the mulch] locks moisture in close to the bark, so at the base, it leads to decay of the bark. It eventually kills off the tree, or it invites voles to come and nest in there and nibble at the base of the tree.”

Instead of the volcano, use “donut mulching”: Leave 3 inches between the bark of the tree and the mulch. Create a larger area of mulch, extending to the edge of the tree’s canopy, and level it out.

At the garden store, with all those plants beckoning to you, gardeners may get distracted by large plants and those with flowers and fruits already taking hold. These superficial qualities can trick you into buying the wrong plant.

“I like to check the roots, because if they are root bound, you have a mature plant that you're disturbing and trying to break up. And so, before making that purchase, have no shame in your game: Lift up the plants, and check the roots,” says Denà Brummer, a University of California Master Gardener and Food Justice coordinator at the City of Hope cancer research center.

Look for smaller plants without fruits and blooms. “Their roots aren't fully established, and then they're young and tender and adaptable. When you buy a 4-foot tomato plant that is already producing fruit, the likelihood of it producing fruit for you later in the season has been hijacked,” Brummer explains.

Soil testing is an easy detail to skip when you’re wrapped up in the excitement of getting a garden started, but Ramirez-Blust insists it’s key to a thriving garden.

“Every plant uses four key minerals, and the level of acidity in the soil determines whether or not the plants can effectively absorb those minerals from the soil. Testing is the only way to know if you have enough and if the pH is right for those plants,” she says.

Send a soil sample to your Cooperative Extension office for lab testing.

“They'll give you the test results and recommendations for whether you should be putting any amendments in your soil, either to adjust the pH or adjust those mineral levels in the soil,” Ramirez-Blust continues.

Or, garden centers and nurseries sell test kits you can use to find your soil's pH; you can also buy them online.

Seedlings started indoors need time to adjust to the outdoors before planting. This process is called hardening off.

“I did teach a friend seed starting once, and she was following along and doing great, but she didn't ask me about the transition from indoors to outdoors. She didn't harden them off at all and put them right out in direct sun,” recalls Jodie Visker, a garden educator and Wisconsin Extension Master Gardener.

Instead, leave your seedlings in the shade outdoors for increasing periods of time each day leading up to planting day.

Ramirez-Blust often sees people purchasing plants without understanding how they'll fit in.

“It's really easy, especially this time of year, to go to the garden center and walk around and see all the pretty plants and buy things. But then when you get them home, you put them in the wrong place because you don't know what that plant needs, or you don't have a place to put them and they end up sitting in their pot and drying out and dying,” she says.

With a master of landscape architecture degree, Lynda would like to see more people clarifying their garden goals and understanding their site so they can bring home the right plants.

“A huge mistake is not having a list,” Ramirez-Blust says. “Now, with technology, there are so many different ways you could do it, but the simplest would be to have a spreadsheet where you write down the botanical name and the common name of what it is you planted. Make some notes about when you planted it, where you planted it, just as a trigger for yourself.”

If you’re more of a visual person than a spreadsheet person, draw a map instead.

This record is essential for you as you care for each plant, and it’s also helpful to the next gardener to use this space, if you ever move away.

This common garden error, overwatering, is one Brummer calls “loving too much.”

“Overwatered plants usually exhibit yellow or brown, or limp or droopy, leaves,” Denà points out. When gardeners contact a Master Gardener for help, they might think the plants have a disease. Often, though, “it ends up being a case where they're essentially … drowning them at the roots, and this is often connected to improper drainage, or whether you have a raised bed that isn't on a proper slope, or your containers don't have enough holes in them. So before starting your spring or summer garden, I like to encourage gardeners to set themselves up for success and make sure they have proper drainage.”

No article can tell you exactly how much to water your plants, because every plant, soil type and environment is different. Follow Brummer's advice for proper drainage, and let your soil conditions tell you when it’s time to water.

The opposite problem is just as common: “loving too little,” or under watering.

Of under waterers, Brummer says, “When they water their summer gardens or spring gardens, they usually just water to surface level. They're in a rush. They're trying to get in and get out, and the water never makes it down to the roots.”

Part of properly watering is using the right tool for the job. You might install a drip-irrigation system to deliver water to the root zone. If you’re watering with a hose, Brummer recommends using a Dramm Waterbreaker nozzle, saying, “It mimics Mother Nature in terms of rainfall. The pressure is right. You don't end up knocking down your [plant] starts, and you don't end up just spewing water that moves away your topsoil.”

Finally, she suggests using the “snowball check”: “If you cannot make a solid snowball with your soil, it's not moist. If it crumbles and it falls apart, it’s not fully saturated.”

Another mistake that Ramirez-Blust ties back to the importance of understanding your plants is neglecting to prune them or pruning them at the wrong time of year. Some plants shouldn’t be pruned, and those that should each have their own best practices.

“A lot of them you can prune in the late winter, early spring, but some, you want to wait until after they flower. You want to wait until the fall to prune them,” she says.

Not pruning at all decreases air circulation, which can lead to disease. When you let a tree or shrub grow unchecked, it puts all of its energy into maintaining this growth, lacking energy for fruit and flower production.

“I think a lot of people are afraid of making the wrong cut,” says Ramirez-Blust. “Most plants are pretty forgiving.”

Too often, says Visker, people look at gardening as something indulgent or unessential. In fact, it’s been shown to be the opposite.

“There’s proven science that gardening regulates the nervous system. Time and resources spent in the garden are not indulgences, but they're cheap therapy,” Visker says.

The next time you’re feeling guilty about spending money on a plant you want or dedicating a whole afternoon to your garden, let go of your discomfort and embrace all that this time outdoors can offer.