(Family Features) - The best gift to give all landscape and garden plants is good soil.

"A wise gardener used to tell me, `Grow the roots, and the top will take care of itself.´ I´ve found there´s a lot of truth in that," said Amy Jordan, horticulturist with Kansas State University Research and Extension.

Other factors can also have a big impact on plant success, Jordan noted. Major ones include wind, hail, pests, flooding, drought, growing days, temperatures, and sunlight (hours and intensity).

"Plants vary widely in sensitivity to environmental factors. That´s why gardeners are more likely to do well when they use native or native-like plants," she said. "It´s also why regional landscapes tend to develop their own `look.´ A typical Arizona landscape won´t look like a typical yard for California, Kansas, Michigan or Georgia."

If plants are sited in the right location for them, however, the factors that determine whether they thrive typically come down to soil, Jordan said. This includes the soil´s pH, nutrients, texture and water-handling ability.

K-State horticulturists advise getting soil tested now - well ahead of springtime planting and lawn work. It´s also a good way to avoid the results-delaying rush that soil testing labs get in spring.

"Soil isn´t static. Plants and runoff can remove nutrients. Moisture content can range widely. The fertilizers and mulches we use have an impact," Jordan said. "That´s why soil testing every three to five years is so important."

Test results are the only way to know if the soil for certain plants needs a pH adjustment. Azaleas, for example, often need more acidity than found in most Kansas soils.

Results also reveal where soil has nutritional deficiencies - or excesses. For instance, lawn soils nearly always need a yearly nitrogen meal, but may already have more than enough phosphorus and potassium.

"To loosen clay soils and improve most soils´ water-handling abilities, the best idea is to regularly incorporate organic materials: peat moss, compost, aged manure or rotted hay," Jordan said. "Of course, doing that is difficult with lawns and established plantings. But, mowing often enough that you can just let the clippings drop will help - without contributing to thatch. Using organic mulches that decay over time - wood chips or compost, for example - will improve the soil around ornamentals and perennials."

Help with soil testing and more about soil improvements is available from any local Extension office.