My butterfly bush
(Buddleia spp.) pushed new growth early due to the warm weather that
was killed by frost. Should I go ahead and cut it back now, or
should I wait to see if it starts to grow again?
were enjoying the much-above-average temperatures in mid-March,
many plants joined in the fun and started growing far earlier
than normal. It was not a big surprise that normal March weather
returned, including a few
heavy frosts that damaged such tender
new growth. While most plants will bounce back with no problem,
some may not be so lucky, especially plants such as butterfly
bush that are classified as subshrubs. These are plants that are
woody near the base of their stems, but produce herbaceous
rather than woody new growth annually.
Subshrubs, like the butterfly bush, are more susceptible
damage over the winter and to frost damage as new growth
begins in spring.
do not go completely dormant in winter as hardy woody or
herbaceous plants do; instead they are quiescent or resting.
This allows them to respond to warm temperatures more quickly
than true herbaceous or woody plants. Sometimes they do not have
the stored energy to push new growth a second time if the first
flush is killed by frost. It is not unusual to lose these plants
when we have a hard frost after they push new growth in spring.
your butterfly bush back until later in spring, once we are
past danger of severe frost, usually mid-May. Your plant may
have the energy to push new growth a second time, but if it is
hit by a frost again, it probably will not push out a third
time. In more normal spring weather (whatever that is!), we
would still recommend not pruning subshrubs back until late
spring because pruning pushes new growth. That is why it is not
a good idea to prune them in fall, either - the new growth might
not harden off in time for winter.
Butterfly Bush 'Potters Purple'
when you prune your butterfly bush not go lower than five or six leaf buds
from the ground. Beyond that, you get into old wood that will
not break new growth.
In addition to butterfly bush, other subshrubs
that are common garden plants include:
beer hyssop (Agastache rupestris)
artemesia (Artemesia spp.)
blue-mist shrub (Caryopteris spp.)
Johnswort (Hypericum spp.)
lavender (Lavandula spp.)
ornamental oregano (Origanum rotundifolium, O. laevigatum)
oregano (Origanum vulgare and cultivars)
sage (Perovskia atriplicifolia)
culinary sage (Salvia officinalis and cultivars)
lavender cotton (Santolina chamaecyparissus)
Composting for the
damage to lawns