Local Experts Address Your Questions About Planting During a Season of Wacky Weather

Pack up your parkas and grab your gardening gloves:

Mid-Missouri springs may not be all sunshine and beautiful days, but the darkest depths of winter have finally passed and springtime landscaping might be possible at last.

If you’re unsure about how to maintain your garden during this tricky season, have no fear. With the help of some local experts, we’ve put together a guide to springtime planting. Consider this Spring Landscaping 101.

When can I start planting?
Because mid-Missouri’s weather is so unpredictable in the spring, finding the proper time to begin planting can seem tricky. If you’re interested in filling your yard with decorative plants such as flowers (known in the gardening world as “ornamentals”), David Trinklein, associate professor of plant sciences at the University of Missouri, says your start date depends entirely on the species you wish to plant.

While a pansy might be able to survive chillier days, vinca and other heat-loving species won’t be happy if the temperature falls below 40 degrees Fahrenheit.

Once you know what you want to plant, it’s important to know your climate.  “The 100 percent frost-free date for Columbia is May 10, meaning it has never in recorded history frozen past that date,” Trinklein says. “The odds of frost increase as you go earlier in the year. The 50-50 frost-free date for Columbia is April 10. Of course, each day that you get further into the calendar year past that date, the odds of it freezing are less.”

If you know you’ll be sticking to more cold-hardy plants, associate professor emeritus of plant sciences Christopher Starbuck says finding a time to begin planting might not be as difficult as you think. “Landscapers often can plant pretty much any time the soil’s not frozen,” he says.

How do I prepare my soil for planting?
Here in Missouri, much of the soil is dense and clay-based, which, unfortunately, doesn’t provide much opportunity for root growth. To make your soil more workable, more friable and more conducive to root growth, you should eliminate any remnants of last season’s vegetation and add organic matter to the soil.

“It is a best management practice — we call them BMPs — to get rid of all the old vegetation, which contains the possibility of disease inoculum and insect eggs,” Trinklein says. “It is also then considered a BMP to, as soon as the soil can be worked, incorporate about 4 inches of well-decomposed organic matter.”

The key phrase here is “as soon as the soil can be worked.” Trinklein says. Many gardeners add organic matter when the soil is still too wet, which can undo years of building good soil structure. To test whether or not the soil is ready for organic matter, he recommends packing some of the soil into a baseball-sized ball and hitting it sharply with the heel of your hand. If the ball doesn’t fall apart, it’s too wet.

A tip for next year: Add organic matter to your soil in the fall. Starbuck says it can take a while for organic matter to break down completely, but once it does, you’ll be reaping its maximum benefit.

How should I maintain my landscape throughout the season?
Maintaining a healthy garden always begins with some good ol’ H2O. “It’s important to get plants off to a good start. By that I mean providing them with adequate water until they develop a deep root system,” Trinklein says. “The rule of thumb is to water thoroughly, but rather infrequently.”

If you only use a little bit of water at a time but water more frequently, Trinklein says there is no reason for the roots of your plant to grow beyond the shallow pocket of soil where your water reaches. Watering thoroughly but infrequently causes the water to move deeper and encourages a plant’s roots to follow it, thus developing a stronger root system.

Starbuck says spring is also prime time for maintenance such as pruning existing plants, a task that many gardeners save for summer and fall. “Pruning is something to put on your March calendar,” Starbuck says. “Get out there and thin crowded plants. Cut back some of the things that have died to allow the new growth to come through.” An added benefit: The lack of growth and leaves during early springtime makes it easier to see what you’re doing as you prune.

What problems might I run into?
With seasonal landscaping comes seasonal weeds, and both Trinklein and Starbuck point to henbit, a purplish winter annual weed, as a common springtime garden woe.

“[Henbit] germinates in the fall and gets protected by the snow and leaves before coming on strong in the cool weather in the spring,” Starbuck says. “It won’t really cause a lot of problems because it’s not aggressive or competitive, but it looks ugly and can make you feel like you’re a bad gardener.”

Starbuck suggests preventing a henbit problem by using a pre-emergent herbicide or mulch in the fall to keep it from ever germinating. If you didn’t take that preventative step, Trinklein says using your hands, a spade or a rotary tiller to remove the weeds will work just fine.

What will my landscape look like in the future?
It’s important to have a plan before jumping in to plant any new landscape. Starbuck says if you plant according to the ultimate size of the tree or shrub, your yard will look rather sparse for the first five or six years. But if you plant your trees and shrubs too close together, you’ll need to plan on ultimately removing some of the plants when they outgrow the space.

“You should have a plan in the back of your mind,” Starbuck says. “What do you want it to look like in 10 years? It takes quite a few years for landscape to develop its true character.”