Page 24 - Griffin Gazette Q3 2017
P. 24

Pot-in-Pot                                                                                                                                                                                                                                                     off-site. It is up to the nursery manager to figure out the extent to
                                                                                                                                                                                                                                                            ®  which drainage will be needed; that can be determined ahead of
                                                                                                                                                                                                                                                               time by taking what appears to be the worst-drained areas of the
The best of both worlds.                                                                                                                                                                                                                                       field and digging some holes slightly deeper than the depth of the
                                                                                                                                                                                                                                                               largest containers that will be installed and duplicating the average
Drive by any nursery that specializes in container grown trees and                                                                                                                                                                                             amount of water that would fall in a typical rainstorm and see how
you'll likely see a field with medium to large size nursery pots sunk                                                                                                                                                                                          long it takes for the water to completely drain.
into the ground. Pot-in-pot tree production has been around for
well over 25 years but really came of age in the late 1990s and                                                                                                                                                                                                Advantages of pot-in-pot are the ability to overwinter in place,
early 2000s. After taking a bit of a dip due to an industry recession                                                                                                                                                                                          eliminate the problem of “blow-overs”, maintain a more constant
around 2007 to 2009, there has been a resurgence in interest in                                                                                                                                                                                                temperature in the root zone because the plant is not as subject to
pot-in-pot with nurseries installing new fields and expanding their                                                                                                                                                                                            the fluctuations of the air temperature, offers year-round “harvest”
existing ones. So, what is pot-in-pot and why is there so much                                                                                                                                                                                                 capability, eliminates root loss associated with digging, is more
interest in it?                                                                                                                                                                                                                                                environmentally friendly because it reduces soil mining.
An in-ground pot-in-pot growing system combines the advantage
of field growing with the advantages of container growing. With field                                                                                                                                                                                          Disadvantages are fewer, but there are some, most notably the
growing, you are growing in place, on site, without moving plants                                                                                                                                                                                              upfront cost of installing the system because of the labor, making
around for spacing or overwintering, and you take advantage of                                                                                                                                                                                                 the initial purchase of socket pots to go in the ground, and of course
the more constant temperatures below ground: slower to warm                                                                                                                                                                                                    a drainage system if needed. But the costs are all up-front, one-
up in the spring, slower to cool down in the fall. With container                                                                                                                                                                                              time costs because you will only install the drainage once, and you
growing, you have full control over your growing environment in                                                                                                                                                                                                will only buy the socket pots once. Other disadvantages are that
terms of growing media, fertilizer program, watering, and drainage                                                                                                                                                                                             pot-in-pot is not an efficient use of space because you need to plan
and total consistency from plant to plant because you don’t have                                                                                                                                                                                               your field with the “harvest” in mind. With field growing, you create
the variation in soils from place to place that would occur naturally                                                                                                                                                                                          your roadways for harvest as you dig your plants. With pot-in-pot,
in the field. Pot-in-pot, which is growing in a container, that is then                                                                                                                                                                                        you have to plan the harvest ahead of time and allow space for the
dropped into another container that is buried in the ground, called                                                                                                                                                                                            carts or trucks to drive through the field for order picking. Roots
a socket pot, combines the advantages of both field and container                                                                                                                                                                                              growing through the bottom of the socket pot can be an issue if the
growing. So you combine the consistency in quality from plant to                                                                                                                                                                                               trees are left in the liner pot too long or if they are an aggressively
plant and faster growth rate that you will find in container growing                                                                                                                                                                                           rooting species. The bottom of the liner pot can become rounded
with the ability to grow and overwinter in one place without the                                                                                                                                                                                               due to lack of support on the bottom so it is necessary to place
labor involved in moving your trees around and picking them up                                                                                                                                                                                                 something in the bottom of the socket pot that will prevent that.
after they blow over in a wind storm.
There are several ways to install a pot-in-pot system but one thing                                                                                                                                                                                            Most pot-in-pot systems use pots in the range of 7-25 gallons, the
that must be paid attention to is the drainage underneath the pots.                                                                                                                                                                                            most common sizes used are 10- and 15-gallon pots. There are
Pot-in-pot can be installed in areas where the ground is incapable                                                                                                                                                                                             a number of ways to treat the area around and between pots and
of supporting any type of growth, but you must have good drainage                                                                                                                                                                                              rows, some growers choose to do nothing, others will invest even
underneath the pots so if it's not occurring naturally as it would                                                                                                                                                                                             more in their installation and put a weed barrier on top of the ground
in a very sandy site, then a drainage system must be installed                                                                                                                                                                                                 to really make the system “maintenance-free” once it is installed.
before the pots are set in the ground. Drainage can be as simple                                                                                                                                                                                               For irrigation, the best method is to use spaghetti tubing with spray
as a trench with several inches of gravel underneath the pots, or as                                                                                                                                                                                           stakes in each pot, although other methods such as drip tape and
complicated as a complete tile drain system that draws the water                                                                                                                                                                                               overhead watering can be used, but they are not as efficient.

                                                                                                                                                                                                                                                               As labor continues to be an issue in the nursery industry, more and
                                                                                                                                                                                                                                                               more nurseries will be investigating the pros and cons of investing
                                                                                                                                                                                                                                                               in a pot-in-pot system as they look to become more efficient in the
                                                                                                                                                                                                                                                               long term.

                                                                                                                                                                                                                                                                                                Grip-Lip

                                                                                                                                                                                                                                                                                                    Pot-in-Pot

                                                                                                                                                                                                                                                                                                            in six easy steps

24 | Griffin Gazette 2017
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