  Pulsars are arguably the only astrophysical sources whose emission spans the
entire electromagnetic spectrum, from decameter radio wavelengths to TeV
energies. The LOw Frequency ARray (LOFAR) offers the unique possibility to
study pulsars over a huge fractional bandwidth in the bottom 4 octaves of the
radio window, from 15-240 MHz. Here we present a LOFAR study of pulsar single
pulses, focussing specifically on the bright nearby pulsar B0809+74. We show
that the spectral width of bright low-frequency pulses can be as narrow as 1
MHz and scales with increasing frequency as df/f ~ 0.15, at least in the case
of the PSR B0809+74. This appears to be intrinsic to the pulsar, as opposed to
being due to propagation effects. If so, this behavior is consistent with
predictions by the strong plasma turbulence model of pulsar radio emission. We
also present other observed properties of the single pulses and discuss their
relation to other single-pulse phenomena like giant pulses.
