I received a question from someone who is growing strawberries for the first time. He has heard that strawberries live for three years and wanted to know if it was because of weeds, nutrients, or what. Here’s my reply:
Strawberry plants can live many years. All of the things you mention can be discouraging. In my experience weeds tend to take over before other factors become important. With good mulching and planning weeds can become less of a factor.
The three year thing is about the need to renovate the plants after a period of time. Organic matter breaks down and is depleted over a couple of years.
The soil structure is no longer able to hold moisture. The mass of roots of older plants quickly takes of water and the soil can’t hold enough water to provide the moist soil that strawberries need. Nutrients get depleted and are hard or impossible to incorporate. Most nutrient application is done as top dressing which is a very inefficient way of getting nutrients to the roots.
With alpines, I have found an additional reason to renovate after a period of time. Unpicked fruit results in volunteers. Self pollinated fruit (pollen from the same plant) and cross pollination of different varieties can result in what appears to be new types of plants coming up and producing fruit.
This is particularly apparent in plantings of white/yellow fruiting varieties. White/yellow fruit is recessive. A lot of crosses will result in the new generation producing red fruit. Non runnering types (clumping alpines for example) can produce volunteers that produce runners. As you can see this can get messy over time without some supervision and prethought.