It’s easy to drop serious cash in a garden supply shop, falling in love with an exotic yucca plant or picking up a bunch of bargain tools.

But when the that sun-loving yucca dies in your shady, wet-soil backyard, or that plastic-handled spade breaks the first time you use it, you’ve wasted money, and you’re frustrated. To help you avoid wasting money, garden experts shared common mistakes they see new gardeners make.

1. You've neglected the soil. Joe Raboine, national design and training specialist for Belgard, a landscape supply firm, said that when someone is digging up part of their yard, installing a raised bed or building a small vertical garden, good soil will mean the difference between plants that thrive and those that wither. Plants need a foot of soil to grow properly, he said. In some yards, much of the original topsoil might be gone and needs to be replaced. In raised beds, Raboine said, "people don't put enough decent soil in. They put in, let's say, a bunch of scraps or gravel or things in the bottom of the container, and it just doesn't give plants enough of a place to grow roots."

Remedy this by buying topsoil or garden soil for yards and potting soil for raised beds and containers.

2. Choosing the wrong plants — and cramming in too many. Tim Johnson, senior director of horticulture at Chicago Botanic Garden, and Renee Young, manager at Christy Webber Farm and Garden, see these mistakes a lot.

“Where a lot of people go wrong from the get-go is they don’t know plants. You’re in the garden center, and you see something that’s in flower and beautiful, and it’s like, ‘Oh, that would look great in this corner of my garden,’ ” Johnson said.

But gardeners need to consider their spot’s growing conditions. A plant that likes marshy conditions doesn’t do well in dry soils, just as a plant that wants afternoon sun might not tolerate shade. Think about your design goals, he said, and talk to the staff for advice on what plants will fulfill those dreams. If your heart is set on a flowering viburnum that can mature at 7 or 8 feet high, but you don’t have the space, ask if there’s a dwarf version that will look just as good.

Young said she sees people stuffing too many plants into small spaces. “People will want to put three tomatoes in a 12-inch pot, and really one 12-inch pot is barely big enough for one tomato plant,” she said.

A tomato plant without a roommate will likely produce more fruits than those in the overcrowded pot that will be fighting for nutrients and light, she said.

3. Buying cheap tools. Bargain tools don't last. That doesn't mean you have to buy the most expensive tools available, but you should invest in quality. Johnson said gardeners should pick up the tools and judge how they feel in their hands. Look for something comfortable and sturdy, he said, which may mean something different to each gardener. Good quality tools have warranties, Young said. She said she likes hand tools by DeWit, which provides lifetime warranties.

“I try to encourage people to go with that tool that’s going to last you a lifetime over something that’s less expensive and may break after a couple of seasons,” she said.

Other brands she recommends are Corona, and for pruners, she said they all use ones by Felco, whether at the store or on landscaping jobs.

4. You didn't think about watering. Raised beds and vertical gardens, especially on rooftops, can dry out quickly. They may need daily watering, and even more when temps hit 90. Raboine and Young said that, at a minimum, you need to buy a watering can and hose. Young said Bond Aeroflex ($24.99 www.jet.com) makes attractive expandable hoses that shrink for storage in small places. Raboine said another option is to install drip irrigation, either with kits, such as those by DIG ($29.94, www.homedepot.com), or create your own by drilling holes in PVC pipes. Improper watering can stunt or kill plants.

5. You're overdoing it on fertilizer or pesticides. If you're gardening to be more environmental, the last thing you want to do is waste money on expensive fertilizers, and many of these can make your plant dependent on the feedings.

“(Synthetic fertilizers) can harm your plant quite a bit. If you over-fertilize, it will burn the roots of the plant, or the plant is so dependent on the synthetic fertilizer that the minute you stop using it, it begins to fail because it needs that constantly,” Young said, who instead recommends organic fertilizers, which feed the microbes and the soil, which then in turn feed your plants.

Johnson frowns on the yearlong fertilizer programs that “weed and feed” lawns, such as the powders or granular types in bags available at garden-supply shops, noting that many release unneeded chemicals. If you feel the need to treat existing insect or weed problems, he recommends using liquid sprays for spot treatments.

“In my mind, from a footprint on the environment, you shouldn’t be applying any sort of a pesticide, whether it’s herbicide or insecticide if you don’t need to,” he said.