Not all plants are equally suited to North Texas conditions.Several require extraordinary care at one time or another, yet there are gardeners who are more than willing to give them that help. The results, if we're careful in our planning and planting, are richly rewarding. Let's look at a few of the most popular, and as we do, I'll point out the pitfalls.Azaleas: We simply don't have a more spectacular spring-flowering shrub, but azaleas require attention to their planting medium to ensure their success. Soils in the Metroplex are almost all highly alkaline, and that's not going to grow you attractive azaleas. You need to dig their planting beds 10 inches below grade, and you need to extend them 10 inches above grade. Fill all 20 inches with a mix that's half sphagnum peat moss and half finely ground pine bark mulch. Mix the planting bed thoroughly, then turn it with a spading fork and wet it again. Repeat the process a day or two later, then another day or two later. Then you'll be ready to plant. Azaleas need more iron than most plants, and iron is insoluble in alkaline conditions. The organic matter is acidic, and it's your biggest secret to azalea success. Plant them in morning sun with afternoon shade.Gardenias: The bed preparation you do for azaleas will also be needed for acid-loving gardenias, so "ditto" for the instructions above. Beyond just the bed-prep, however, you'll also need to protect your gardenias from temperatures below the low 20s. Frost cloth draped over the plants and weighted to the soil will give them several degrees worth of protection. Be prepared, too, to add an iron/sulfur soil-acidifier to their growing mix a couple of times every growing season.Japanese maples: No small tree has so captured gardeners' attention over the past 25 years as the many different types of Japanese maples. They're stunning small accents, with their maroon or green foliage. Japanese maples are great to mark entryways or to pull the eye into the back of the landscape. However, they have to have shade. They're native to a cool, humid climate, and they'll scorch badly if you plant them out in the sun. Shade and moist soils: your keys to success.Wisterias: We grow them as big, luxuriant vines, and we grow them as artificially manicured little trees. Still, wisterias confuse us and lead to frustration. That's because they too often fail to bloom. In this case, however, there's no one easy solution. You mustn't prune them in winter, because you'd be removing their flower buds for the spring. You need to stay away from them with nitrogen lawn food in fall, because it suppresses the formation of flowers. They need full or nearly full sun, and they're highly susceptible to the same iron deficiency you'll see with azaleas and gardenias. In their case, however, it's not practical to try to amend their soil, because their roots are so extensive. Probably the one thing that might help convince them to bloom would be to root-prune wisterias in September. Use a sharpshooter spade to cut your plant's lateral roots 15 or 18 inches out from its trunk. The slit should go 12 to 15 inches straight down into the soil. That often shocks wisterias into production of flowers the following spring. It's at least worth a try.Fringeflowers (Loropetalum): OK. I have to confess something on this popular late-winter-flowering shrub. I'm just tired of it. It grows for 5 or 8 years, and it dazzles us with its raspberry-red blooms in the spring. But, the plants develop iron deficiency, and they start yellowing, thinning and dying. You'll need to plant them in the same mix that we prescribed for azaleas above. Then you'll have to keep them trimmed to maintain their size. Many varieties, especially the older ones, get rangy and spindly as they mature. I'm willing to go the extra mile with the other plants that I've listed, but I've retired from the fringeflower business. Never again. Not in my Blackland landscape. That's the way I solved that problem.Aspidistra (cast iron plant): This is probably the least-known plant that I've listed. It's also one of the most striking. It grows to 24-30 inches tall, and the 4-inch-wide leaves stand bolt-upright. It's a slow and deliberate grower, which is why I'm prepared to cover it any time the temperature will be dropping into the low 20s or colder. I've been known to leave frost cloth over it for weeks at a time in the winter. It's a lovely tall groundcover or background perennial, and as its name suggests, it never has any type of a problem. (Other than cold.)Roses: The most popular flower in the world grows wonderfully in Texas. Unfortunately, so does black spot fungus. Most rose varieties are highly susceptible, so you'll want to plant them in beds that are out in the open (for best air circulation) and raised 6 or 8 inches above the surrounding grade (to ensure good drainage). Best option of all: Plant the Texas A&M-designated EarthKind varieties. They've proved their resistance to black spot and other common rose problems. Your nurseryman will know what you're wanting.Neil Sperry publishes "Gardens" magazine and hosts "Texas Gardening" from 8 to 11 a.m. Sundays on WBAP AM/FM. Reach him during those hours at 800-288-9227 or 214-787-1820.