Nursery seedlings and/or cuttings experience optimal growth conditions without water, heat and radiation stresses. Transferring young plants to garden conditions can lead to planting stress but this can be minimized by planting them as soon as possible and watering them in well.
The following example illustrates the importance of this:
Over winter, young Juniper (Juniperus spp.) plants were raised in containers of sand. We transplanted them into our local soil (sandy loess) and watered them in. The next day the sand around the plants was found to be dry! This happened because of the differences in soil texture and their effects on the soil water tension. In this case sand has a much lower water tension than the surround sandy-loess and water moves from the sand to the sandy-loess through gravity and capillary flow. The plants survived thanks to daily watering.
Good practice for planting should take account of the following steps and the gardener should pay attention to several phenomena:
First: Nursery plants are usually grown in much better conditions than those in the garden. If you are growing your own nursery plants try and reproduce the same shade, humidity and soil conditions to those of their new site (see Notes 1 and 2).
Second: Nursery pot soil mixture is generally airy and light with low water tension. Here begin the difficulties that gardeners may experience. In order to encourage optimum growth conditions for the plants, planting should be done as quickly as possible (see Notes 3 and 4).
1. Be sure to keep the plant pots out of direct sunlight (most are black and will get very hot). High temperatures can damage growing roots and new roots are vital to rapid plant acclimation. Also, care must be taken not to allow the roots to dry out while transplanting them from pot to soil.
2. Young plants can be hardened to garden conditions by an intermediate step of placing the pots in areas that provide less shade and humidity than the nursery but not as much as they will experience when planted in the garden. This intermediate step should be carried out over several days and care must be taken so as not to overstress the plants.
3. Usually the garden soil will have a higher water tension than the nursery soil. This difference creates a net movement of water from the root ball into the surrounding soil. Without paying attention to this the plant will suffer immediate water stress. Be sure to water every day. We, at Green Point, usually divide the weekly irrigation amount into seven daily amounts in order to maintain adequate soil moisture conditions around the plant.
4. JNF potted plants tend to be grown in ‘Quick-Pots’ – an open bottomed container. This style of pot allows air pruning of roots. A benefit of this is that root circling is minimized and new, white root production is maximized. These new, white roots are a key to rapid plant establishment in the garden.
Plant in well watered soil helps to create an immediate and good soil-root contact.
It should be emphasized that:
– Everything written here is suitable for all pot sizes from the smallest individual pot to blocks and large tree planting bags.
– If the container soil conditions are similar to the garden soil then dehydration problems do not arise.
– Be sure to pack the soil to fill all the air spaces around the seedling roots, creating good root-soil contact. Fill large planting holes with water before planting, or flood the area around the planting hole to minimize water stress. Watering the plants immediately after planting will wash loose soil into soil voids and help the plant establish quickly.
– Be sure to make the planting hole much larger than the size of the seedling container to ensure well turned, non-compacted soil for good root growth. In rocky areas that will be planted with saplings prepare a one cubic meter pit (minimum) to ensure good future tree root anchorage