I would like to grow some “barometer plants” to use as an early warning system for my garden. What plants are first to respond to frost, first to bolt and first to wilt? Is this a waste of time?
It’s not a waste of time, but I’m not sure you’d have to invest in any particular variety. I would use half-hardy annuals that are sensitive to frost, such as cosmos, lobelia or nasturtiums. One side of my tiny garden can act so differently from the other that only by growing the same plant in several spots have I learned which plant can tolerate what.
An urban back garden is generally a sheltered place because of the effects of the urban heat island, so worrying a great deal about frosts is not necessary; there’s usually plenty of warning when a cold snap is coming. If a vegetable goes straight to seed (bolts), this is often an indicator of environmental stress; it can also be down to changing day length and temperature. If you want resilient plants that can withstand stress, worry more about improving your soil and spend more time making compost. Ultimately, it’s the strength of the roots that allows plants to withstand droughts and extremes of cold and heat.
