%0 Research article
%T Extending the planting period of dormant and growing Norway spruce container seedlings to early summer
%A Luoranen, Jaana
%A Rikala, Risto
%A Konttinen, Kyösti
%A Smolander, Heikki
%D 2005
%J Silva Fennica
%V 39
%N 4
%R doi:10.14214/sf.361
%U https://silvafennica.fi/article/361
%X In order to make mechanized planting economically viable, the present  spring planting period for Norway spruce (Picea abies (L.) Karst.)  seedlings in Scandinavia needs to be extended. To evaluate the  possibilities to extend the planting period, six field experiments were  established in four years during which frozen-stored, dormant seedlings  and actively growing seedlings targeted for spring planting were planted  regularly from mid-May to mid-July or the end of August. The survival  of actively growing seedlings did not differ between planting dates from  mid-May to mid-July. For dormant seedlings, however, the later in  summer they were planted the lower was the survival. Oversized seedlings  grown in the nursery in containers of too small volume, which were  usually planted after mid-June, resulted in reduced growth of seedlings  after planting. Root egress (growth of roots from root plugs into the  surrounding soil) was most rapid in July and early August and slowest in  May and September. Results showed that with dormant seedlings the  planting period can be extended from May to mid-June without increasing  mortality or reducing growth. The planting period for seedlings stored  outdoors and those seedlings that were already growing in June for the  purpose of spring plantings can be extended even longer, but it must be  kept in mind that the risk of mechanical damage and reduced growth  increase due to brittleness of the shoot and increased height. Further  research is needed to evaluate the risks in practical scale plantings  and with seedlings that are specially targeted for planting after  mid-June.