Summer planting is an effective means of extending the annual planting season beyond that which is appropriate or possible with cold-stored spring plant seedlings.

Increased performance - particularly on high elevation sites - from stress tolerant, fully budset, summer planted seedlings is expected over cold-stored, late spring planted seedlings subjected to lengthy cold storage and facing a short growing season in which to flush out, establish and achieve frost hardiness prior to fall.

Brief History

The first summer planted seedlings in British Columbia were 2-year-old ( 2+0 ) seedlings targeted for delivery around mid August. Delivery dates for 2+0 were brought forward to July with further experience in the nursery.

To reduce the planning time required for reforestation programs, K&C pioneered the development of cultural techniques to successfully and consistently produce 1+0 summer plant seedlings for our clients.

Operational production began in 1987 with seedlings targeted for late July delivery and further work was carried out to produce 1+0 summer plant seedlings for a wider range of delivery dates and planting sites.

In 1993, we began operational production of 1+0 summer plant seedlings for early June delivery to accommodate lower elevation and/or drier sites.

Our current 1+0 summer plant program is around 5 million seedlings annually.

Delivery Dates

We can provide 1+0 summer plant seedlings for delivery from the 1st week of June through to the end of September. The majority of our 1+0 summer plant production is shipped between late June and mid July.

Stock Types

Species currently grown under this cycle include White, Engelmann and Sitka Spruce; Lodgepole, Ponderosa, Jack and Western White Pine; Western Larch; Douglas-fir and Western Hemlock. Species currently available for early June delivery include White and Engelmann Spruce; Lodgepole, Ponderosa and Jack Pine; Western Larch and Douglas-fir.

"Styroblock" container sizes available include 310B, 313A, 313B, 410, 415B, 412A, 415D, 512A, 515A and 615A. We recommend the 410 container size to provide the best combination of seedling quality and delivery date assurance.

Advantages

• Shorter silviculture planning and seedling ordering time frames than 2+0 summer plant seedlings.
• Completion of harvesting and / or fall site preparation prior to ordering seedlings.
• Late spring / early summer site preparation prior to planting.
• Quick response to emergency seedling need situations due to a short growing cycle.
• Elimination of lengthy overwinter cold storage of seedlings and associated costs.
• Better shoot-to-root ratios and less root bound plugs than the 2+0 cycles.
• Better root development and seedling establishment prior to the first flush over cold-stored seedlings.

Applications

Although the 1+0 summer plant cycle is targeted for moist, higher elevation sites, it has been applied to a wide range of latitude, elevation, aspect and soil moisture regimes.

We generally recommend its application to sites characterized by higher elevation, north or east aspects, sufficient soil moisture to sustain root growth for 3 weeks following planting, and lower vegetation competition potential, particularly where people are implementing this cycle for the first time.

Cultural Requirements

Producing well developed 1+0 summer plant seedlings requires a well controlled growing environment, provided for through computer regulated, climate controlled greenhouses.

Early sowing dates, warm temperatures and proper nutrition are essential to achieve high quality morphological specifications on this short growing cycle. Sowing dates are carefully matched to the delivery dates requested. Maintaining a strong nutritional program throughout the growing season ensures the seedling health essential for active root growth during the immediate post-planting period.

Progressive conditioning promotes the physiological changes necessary for seedlings to attain a high degree of stress tolerance, and is achieved by manipulating the growing environment through gradual alterations in temperature, photoperiod, air movement and moisture regime.

Gradual, progressive changes to the environment are used to ensure seedling health is maintained throughout the process. When conditioning is complete, seedlings will have been exposed to the natural fluctuations of an outdoor environment for 4-10 weeks depending on the delivery date requested.

Reduced photoperiod systems enable the use of short daylength treatments to induce and/or maintain budset. This provides effectively timed control of pre-pack seedling physiology and morphology and hence the ability to meet specified delivery dates. These treatments also impart an extra measure of stress tolerance to seedlings.

Stock Handling

Stock handling procedures are designed to maintain optimum physiological condition and prevent seedling damage throughout the process from pre-pack to planting. This is very important since summer plant stock, although packed in a quiescent state, is still physiologically active. The photosynthesizing shoots and actively growing roots are vulnerable to damage from careless handling.

Prior to packing, seedlings are watered to maintain adequate root plug moisture throughout the handling process and to reduce the need for additional watering in the field.

During packing, seedlings are bundled, the root systems wrapped to prevent damage, and the bundles packed vertically ( where practical ) directly into premium quality cartons designed and treated for moisture resistance and strength. Carton liners are not used ( as with cold-stored stock ) so that excess water can drain from the cartons.

Cooling takes place in a room at +5 C with constant air flow, open on pallets to dissipate heat. Seedling temperatures are reduced to +6 C overnight. The cartons are closed in the morning and shipped in trucks with reefer temperatures maintained at +6 C.

In the field, cartons should be stored outside in a shaded area, such as in or near timber. They should be covered with an elevated tarp to avoid direct sunlight, protect from rain and foreign material, and allow good air circulation. Cartons should be well spaced, open and the bundles placed upright ( if not already done so at the nursery ).

Good air circulation will be ensured around the cartons and seedlings, preventing heat build up and providing indirect light to the seedlings if these procedures are followed. Roots should be checked daily for adequate moisture and should be watered if and when necessary. Seedlings should be planted within 3-5 days of delivery and within 7 days at the latest.

Post-Planting Development

Our experiences indicate that summer plant seedlings do not, under normal climatic conditions, exhibit any significant shoot extension or re-flush after planting. We believe this is due to pre-pack conditioning and physiology, normal planting shock and a range of environmental changes experienced by the seedlings.

We do observe continued diameter and root growth after planting to a degree dependant on planting dates and site conditions. This post-planting development contributes to good seedling establishment prior to the winter period.

We would be happy to discuss our 1+0 summer plant cycle with you in greater detail to determine how it might complement your existing reforestation program.