Now that the temperatures are where they need to be for cool-season grass growth, our Poa annua nursery is taking off again. You can see there are spots that have yet to fill in. One thing we learned from this exercise is that Poa annua requires a much higher seeding rate than we initially thought. Creeping Bentgrass, for example, has a lower seeding rate because of stolons (above ground lateral stems) that creep along the ground, filling voids and voids. In the simplest terms, it can grow 'sideways.' Poa annua, on the other hand, has what's called a bunch-type growth habit. These types of grasses are very upright in growth and produce shoots from the crown of the plant, but they don't creep. This means at establishment, it's important to have more seeds per square foot for adequate coverage. In another couple weeks, the nursery will be dense but it is taking slightly longer because of the less than ideal seeding rate. You can in the photo above, that Hap approves of the work we're doing on the Poa annua nursery.
The drawing above illustrates the three different growth habits that grasses can have along with a primary example of a cool-season grass with that particular growth habit. Interestingly, all warm-season grasses have both rhizomes and stolons and this is what makes them so aggressive in the deep south. Think about a walkway through a Bermudagrass lawn that constantly needs to be edged. That's an example of aggressive lateral growth by way of rhizomes and stolons. If that same walkway was surrounded by a bunch-type grass like Poa annua or Perennial Ryegrass, it would never need to be edged because those grasses lack the ability to spread laterally.
One final example of a practical application of growth habits...
By now, I'm sure everyone has seen this graphic at least once. There are actually two things happening here. First, by using the linear divot pattern, you're impacting less square footage. That's the obvious benefit. The secondary benefit is that by leaving a strip of turf between the linear divots, is allowing the divot line to heal by way of lateral growth (as discussed above), from two sides. When bentgrass can creep in from two sides to fill a 2-3" wide void, as opposed to a huge void shown in the concentrated divot pattern, the tee will heal much quicker. The problem with the scattered divot pattern is that it consumes the largest area of the three, which can be a problem at golf courses with undersized teeing space. However, I would much rather see the scattered method over the concentrated method because it will heal a lot faster.