There has been a strong interest in planting redwoods in recent years, with Bill Libby’s enthusiasm and initiative bringing the Kuser collection to New Zealand. Bill encouraged people to trial redwoods using good establishment practices and on sites where conventional wisdom says they would not succeed.
American interest in large-scale redwood plantings in New Zealand has really caught the tree grower’s attention.
Good quality tree stocks, weed-free establishment and sufficient nutrition are all important for successful establishment and early growth. Redwoods are extremely intolerant of grass and weed competition; 2m herbicide spots or total weed control gives the best results.
Severe exposure, strong winds and insect attack will result in apical bud damage. Caterpillar damage has resulted in the temporary loss of leaders in some trials, but with little damage the following season. Most older redwoods in New Zealand have good form and volume production, so this insect attack may only occur in young plantations.
We have supplied redwood trees from Invercargill to Kaitaia and most places in between. Nelson seedlot seedlings have above average growth and form when compared with other seedling lines. Bill Libby advised us on our clone selections from California and is confident that we will further improve on the spectacular results that current clones produce. Testing the wood properties of these clones has begun, with comparative trials being planted this winter.
In 2005 we suffered wind throw in a stand of pruned 20-year-old Pinus radiata, it continued to ‘fall over’ and had to be felled. In winter 2006 we planted the 40 hectares with redwoods including a full Kuser trial. Adjacent Golden Downs Forest grows excellent douglas fir, so we interplanted the non-Kuser area with 800 Douglas fir per hectare, matching the 800 redwoods. This spreads the risk on this north facing Moutere clay soil at 400 metres above sea level, subject to occasional snowfalls.
Total weed control was achieved in late October 2006 by helicopter-applied herbicides. Fertiliser will be applied this spring subject to soil tests. This will be an interesting trial on a site harsher than most recent redwood plantings.
REDWOODS IN NELSON
Nelson is fortunate to have groups of trees that produce viable seed on a regular basis. Imported Californian seed from San Francisco and Santa Cruz seed zones has also been grown in recent years.
In the last five years significant numbers of redwoods have been planted in commercial plantations. Some of the growth rates have been spectacular, highlighting the need for well grown plants with active mycorrhizal inoculation, excellent weed control for at least the first two years and correct siting with adequate soil moisture and fertility.
We have successfully grown one-year seedlings, topped at 35cm, similar in specification to a 1/0 radiata. Our traditional planting stock has been a two year old 1/1 transplant producing an advanced root system and heavy calliper stem diameter, and 50-75cm in height.
Clone selections from California are currently being bulked up for cutting propagation and will be available from 2008 onwards.