How the Cold Spring Sets Us Back



I am sure you are keenly aware that this spring's weather has been the polar opposite of last year. Cool, wet temperatures have kept our soils saturated and our soil temps well below average. The moisture is a welcome nuisance as it helps restore soil moisture lost during last year's drought, but the low temperatures are not doing us any favors.

We need to seed, and seeding requires a few things to ensure germination: seed-soil contact, moisture, and adequate soil temperatures (50-55 degrees). Without one or more of these requirements, the germination becomes inconsistent at best. Our soil temperatures at 3" were 57.6 degrees as of March 6th last year. We have yet to reach that temperature this year, which puts us 44 days behind last year. Considering the germination period for Ryegrass is five days, we could have had seedlings well on their way to maturity by this time last year.

Golf course superintendents and home owners alike have an uphill battle this year when it comes to repairing turf damage caused by last year's heat and drought. Be patient. The soil will eventually warm and, with any luck, we will have time to get grass out of the ground and mature before the stresses of summer arrive.

Below you will find an article published by the University of Nebraska on this very topic.

When will turfgrass seed germinate this spring (if ever)?
April 17, 2013

Though some of the dormant and winter seedings are germinating in the warmest of areas, spring temperatures are currently averaging two to eight degrees Fahrenheit lower than normal across Nebraska (Figure 1) and the northern Great Plains. Table 1 lists the optimum germination temperatures used in germination testing, but germination will begin at temperatures lower than listed. Temperatures below optimum will slow germination and also development of seedlings. Will seeds eventually germinate and seedlings develop? The answer is a resounding “Yes”, and germination is often seen when soil temperatures near the seed (surface) consistently rise to 50F during the day. Unfortunately, the later these seeds germinate and the slower they mature, the less able the young plants will be to withstand summer stress. Thus irrigation and pesticide use will likely be needed throughout the summer. Another point of caution is herbicide applications may have to be delayed even beyond the label recommendations if the label recommendations are based on days after seeding or potentially days after emergence.

Figure 1. Departure from normal temperature 3/17/2013 to 4/15/2013

(Courtesy of High Plains Regional Climate Center)

Table 1. Optimum temperatures for seed germination.

Turfgrass Species                          Optimum temperatures for seed germination*Creeping bentgrass                         59-86
Annual bluegrass                            68-86
Kentucky bluegrass                        59-86
Tall fescue                                      68-86
Perennial ryegrass                           68-86
Buffalograss                                    68-95

*Temperatures separated by a dash indicate an alternation of temperatures. The first number is for approximately 16 hr and the second for approximately 8 hr, which would translate into cooler temperatures in the 16 hours of evening through morning followed by the 8 hours in the heat of the day. Adapted from Beard’s Turfgrass Science and Culture.

Zac Reicher, Professor, Turfgrass Science, zreicher2@unl.edu