  We present the results of muon-spin relaxation ($\mu^{+}$SR) measurements on
antiferromagnetic and ferromagnetic spin chains. In antiferromagnetic
CuF$_{2}$(pyz) we identify a transition to long range magnetic order taking
place at $T_{\mathrm{N}} = 0.6(1)$ K, allowing us to estimate a ratio with the
intrachain exchange of $T_{\mathrm{N}}/|J| \approx 0.1$ and the ratio of
interchain to intrachain exchange coupling as $|J'/J| \approx 0.05$. The
ferromagnetic chain [Sm(hfac)$_{3}$(boaDTDA)]$_{n}$ undergoes an ordering
transition at $T_{\mathrm{c}}=2.8(1)$ K, seen via a broad freezing of dynamic
fluctuations on the muon (microsecond) timescale and implying
$T_{\mathrm{c}}/|J| \approx 0.6$. The ordered radical moment continues to
fluctuate on this timescale down to 0.3 K, while the Sm moments remain
disordered. In contrast, the radical spins in [La(hfac)$_{3}$(boaDTDA)]$_{n}$
remain magnetically disordered down to $T=0.1$ K suggesting $T_{\mathrm{c}}/|J|
< 0.17$.
