(column by Elizabeth Exstrom)
Warm Weather Now, But Spring Risks Remain
The recent summer-like temperatures have been a welcome change, but this is Nebraska. It didn’t take long for cooler weather to snap us back to reality, and we are only in March. These temperature swings may have had us wearing shorts one day and sweatpants the next, but they can also impact our landscapes.
While those 70-degree days helped shake off the winter blues, they may set plants up for a challenging spring. Early blooms and swelling buds are nice to see, but our average frost-free date is still around Mother’s Day. That means we still have weeks of potential frost and even the chance of a late-season snow.
The biggest concern with early warm weather is the risk of plant damage when temperatures drop again. Roses and some perennials may experience dieback on new growth, especially if they were pruned before a cold snap. Flowering bulbs can suffer damage to both leaves and blooms. Trees and shrubs that have already begun to leaf out or bloom are also vulnerable. Freezing temperatures can damage flowers and newly emerged leaves.
The good news is that many trees and shrubs can produce a second set of leaves if the first is damaged. However, flowers are a different story. If blooms are lost to a freeze, the plant will not produce a second round that season. Producing new leaves also takes a great deal of energy, which can leave trees stressed.
To help stressed trees and shrubs recover, provide about one inch of water per week if rainfall is lacking. Avoid fertilizing, as this can add additional stress. It’s also important to monitor for insects and diseases, which often target weakened plants.
The amount of damage from a cold snap can vary widely depending on location. Plants on the south or west side of a home—especially near brick surfaces—may develop earlier due to reflected heat, making them more vulnerable. Low-lying areas can also be at higher risk, as cold air tends to settle in those spots. Even within the same yard, plant response can differ based on exposure and growing conditions.
With the recent warm weather, many homeowners are eager to apply preemergence herbicides for crabgrass control. However, it’s important not to rely on air temperature alone. Soil temperature is the key factor. Monitor soil temperatures at a four-inch depth and aim for around 55 degrees before applying.
Preemergence herbicides work by preventing weed seeds from germinating. Common active ingredients include dithiopyr, pendimethalin, and prodiamine. Be sure to read the product label carefully to ensure proper use. For best results, water the product into the soil after application to prevent breakdown from sunlight.
Consider using a split application for longer-lasting control. Apply half of the recommended rate when soil temperatures approach 55 degrees, then apply the second half six to eight weeks later. This approach can help extend weed control throughout the growing season, especially in years with an early start.
Enjoy the warm days when they come, but remember spring in Nebraska can be unpredictable. Take time to check your landscape, watch for signs of damage, and be patient when it comes to spring lawn care. Timing is everything.
Elizabeth Exstrom is a Horticulture Extension Educator with Nebraska Extension in Hall County. For research-based gardening information, contact Elizabeth at elizabeth.exstrom@unl.edu, visit huskerhort.com, or follow HuskerHort on Facebook and Twitter.
