Some root pruning is better than none. To maximize the root pruning efficiency, one might consider the RootBuilder High 5. Be sure to cut any circling or kinked roots on the outside as you transplant from a conventional pot to a RootMaker.

There are transplanting benefits when the root system of any plant is improved. A seed of every plant starts out with a taproot. The sooner this taproot is stopped and secondary branch roots are stimulated, the greater the benefits. Some plants are more forgiving and produce secondary roots more readily. In general, the woodier the plant, the more dramatic the results.

A. Determining the optimum time to remove seedlings from containers will vary season to season and at your location versus another grower. Remember, it is always better to remove seedlings early, even if this means a small amount of mix falls away, versus leaving the plants too long. The plants were difficult to remove as a result of two factors: 1. They ran out of space for additional root growth. There are sequential flushes of roots as root tips are air-pruned and secondary roots are produced. With the production of the third flush of branch roots, there is little additional space for these new roots to exploit, so they fill any remaining small voids. 2. As the seedling grows on top, so do the roots, both in numbers as a result of air-pruning, but also roots grow in diameter. It is primarily the increase in diameter of the roots that puts pressure on the sidewall of the container and makes removal more difficult. In the future, consider transplanting seedlings just as the root ball can be easily removed and into a container large enough to support additional root growth for the rest of the growing season if space and overwintering are factors or into the next step up in container size relative to your production goals. Think of transplanting like driving a truck---- If you make timely transplants, you keep the plant growing, what I call ‘full throttle’. On the other hand, if you leave the plants too long and they approach or come to a full stop, it takes considerable time and wasted energy to get growth rolling again.

The white RootTrapper® conserves water, greatly slowing water exit and creating a fibrous root system which is more efficient in water absorption. Because of this, it may be necessary to reduce your watering program. For example, according to our research, 8 hours after watering, a porous sidewall black fabric container loses 64% more water than a conventional plastic pot and 80% more water than a RootTrapper®. The RootTrapper® II has the bottom two inches of the sidewall not laminated. This improves drainage and aeration where the soil column needs it most, while not exposing the entire sidewall to excessive evaporation and water loss. The RootTrapper® “Grounder™” version has a porous base that allows roots to penetrate and thus tack to the ground to greatly reduce blowover and reclaim some water and nutrient runoff. Drainage is also greatly improved with this modification. RootTrappers® also can be specially made to fit your socket pot to solve the problems of in-pot productions. Root escape is almost non existent and a fibrous root system is created. Additionally, when harvested, root temperature is much lower because of the white outer surface. Consider the water requirement/tolerances of the species and nursery site conditions such as soil type, wind, and topography to determine which version is right for you.

Tree seedlings in RootMaker® II propagation containers are routinely taken to the field when they are 12 to 16 inches tall and 3 to 4 months old. This has been done by hundreds of nurseries across the country. Most do fall planting – September or October and some have drip irrigation and others do not. (Drip irrigation assures nearly 100% survival. But even without drip irrigation, the success rate is quite high, except for the occasional severe drought immediately following planting). The primary reason for planting tree seedlings at a larger size is that in the small growth stage, telling seedlings that will make winner trees from culls is tough and the cull rate may be as high as 25 to 30% or more for the oaks. In one gallons, the cull rate drops to 7 to 10% and with 3 gallons to 2 to 3%.

Treflan and Pendulum granules are safe and effective ways to reduce lots of weed species. Spot spraying with Roundup® where Chaps® protects stems or using a shielded nozzle works well for perennial weeds and those that are not controlled by Treflan and Pendulum. (See Spring 2001 Newsletter)

There is nothing wrong with germinating seeds in flats then transferring seedlings to RootMaker® trays – as long as it is done when the seedlings are quite small. This is what I practice at Lacebark for many of the species I work with – and primarily because seed germination can be so unpredictable and in order to get 32 of the same size in one tray, compared to a few big ones that over shadow the smaller ones.

RootMaker® containers, including RMII-32 propagation trays work on annuals, perennials, vegetables, etc. just as they do on woody plants. The more the root system is forced to branch the more the nutrient absorptive surface is increased, which in turn increases growth and overall plant health. Interestingly this has also increased both flower production and fruit production for same reason – more roots. Typically, plants grown in smooth round containers are taller and more slender and have fewer branches and flowers compared to those grown in RootMaker® containers.

For Knit Fabric, in-ground, containers the spacing should be roughly 4 foot centers for nearly all species. Consider the growth and development of trees in 12 or 14-inch containers versus 18 inch. Trees in 12 of the 14-inch containers will typically be harvested when the stem diameter is 2 inches. For trees in 18-inch diameter containers that are going to be grown to a larger size (one more growing season) the removal of the lower limbs should begin at this point. As the longer lower branches are removed, the branches at a point roughly 4 feet above the ground are not as long and therefore can be left to grow another growing season without appreciable interference with each other. On the other hand, if 24-inch diameter Knit Fabric containers are used, the spacing should be about 5 to 6 feet on centers to allow for proper branch development on a tree of 3.5 to 4.0 inch stem diameter. As for spacing between rows, 10 feet is very workable for most species. The only reason to use rows wider would be if your machinery were of a larger size. Spacing trees 4 feet in the row and 10 feet between rows provides approximately 1000 trees per acre. Remember that most plants have developed methods that allow leaves in the inner branches to function similarly to those in full sun. There are only a few species that are particularly sensitive to shading by an adjacent plant; those are primarily the pines, and other conifers and particularly bald cypress.

With good watering practices, NO. Research with a number of species has not shown this to be a problem with good water management. However, if you over water continually and have water exiting drain holes after each irrigation, air-root-pruning would be reduced. However, once plants are removed from such a humid environment, any roots outside the container wall will be dehydrated and will not be a problem.

It is not necessary to ship the plants in the RootBuilder® container for the root ball to stay together because the roots are so fibrous. The technique that both customers and nurseries are pleased with is to lift the trees at the nursery, remove the RootBuilder® container and cover the root ball with black stretch wrap. This gives the nursery the re-use of the container without the fuss of deposits and returns, and the customer will have less to handle and dispose of at the landscape site. It is best to use black stretch wrap. Clear stretch wrap will cause a “greenhouse effect” that will accelerate heating and lethal root temperatures could be reached.

If the plants are to be in the RootBuilder® container a matter of 2 or 4 months and are not particularly tall or have a large head, it may work best to use 6 mil poly. This stops all roots from leaving the confines of the container and all are air-root-pruned on the container sides. If you will cut squares of 2.5 to 3 ounce weed barrier type fabric and place inside the RootBuilder® container after it has been placed on the plastic, the roots will grow into the thin fabric and secure the bottom more rapidly. If plants are to be grown in the RootBuilder® for considerable time or if they are particularly tall or have a large head, it is best to use squares of the RootBuilder® Base material. This material is a knit fabric similar to that used in the Knit Fabric containers, but has been coated with vinyl to make it especially tough and long lasting. Simply place the material on the ground cover cloth or on bare soil and set the RootBuilder® container in place, and fill with potting mix to surround the root ball of a tree previously grown in a Knit Fabric container or harvested with a tree spade. Roots will grow through the RootBuilder® Base and anchor the plant against all but severe winds. At the time of sale, rock the tree back and forth (most species) or tilt and cut roots with a sharp flat bladed shovel (elms and members of the legume family).

A current estimate is that 50% remove the Knit Fabric container and place the trees in above ground containers for finishing. The RootBuilder® container is working well in this capacity. The other 50% are harvesting trees, allowing 3 or 4 days to “cure”, then stretch wrapping the root ball and sending it to landscape jobs. A few are removing the container at the nursery before covering with stretch wrap in order to insure that the fabric is removed at the time of planting. (Note: It is important that instructions are clear that the Knit Fabric container must be completely removed prior to installing in a landscape.)

No. When the Knit Fabric container is installed and filled with soil, the fabric is pressed firmly against the outside wall of the augered hole. When roots grow out and contact the fabric, they are guided into the surrounding soil with no opportunity to circle. However, if the soil is so heavy and/or the soil was moist enough to cause glazing of the sidewall of the hole, you should reconsider your planting procedures. By creating berms 6 to 8 inches high in the rows and installing the Knit Fabric containers in the center of the berms, drainage will be improved substantially. Remember, if oxygen is limited, root growth will be slow. If your soil is particularly subject to glazing of the sidewalls, you will likely benefit from growing a soil building crop such as sudex between crops and using the berm technique.

At this point in time I know of no shrub, even shrubs that are often grown as small tree forms, that do not grow well in the 5-Gallon Grounder™. The only tree that I do not like in this container is Pecan and that is because the root tips are so large that they do not grow through the openings and instead circle.

Yes, Simply set the container on the surface of the soil and fill with a soilless mix. As roots grow out the holes in the ledges in the sides, they will be air-root-pruned. Yet the roots that grow through the holes in the bottom will extend into the soil below and both anchor the plant and accelerate growth. Another technique that works well on heavy soils is to set the 5-gallon Grounder™ on the soil and surround the containers with a good mulch that drains well. This could be pine bark, wood chips or simply sand. This mulch material allows roots to grow out and speed plant growth and insulates the roots in the containers from excess heat and cold. This procedure is working well for a RootMaker® grower in the Chicago, Illinois area.

A good soilless mix works best. Because there is little contact between the soil outside and the mix inside, a mix should be used. This is a distinct contrast to the Knit Fabric container where there is a great deal of contact between inside and outside through the thousands of small openings. Remember that the soils must drain well for a soilless mix in the Grounder™ to work well.

There is no precise answer here as soils are extremely variable. However, if you suspect that the soil is becoming sufficiently compacted to restrict oxygen and inhibit root growth and drainage, do a perc test. Simply remove the container, fill the hole with water, wait about 30 minutes and fill the holes again. If the hole is still holding water after 24 hours, it flunked the perc test and actions should be taken at the earliest opportunity.

A 12-inch auger works well, especially if it is fitted with a depth control leg that insures that each hole is 7 inches deep, even if the ground is somewhat uneven. I took the “teeth” off my 12-inch auger and sharpened edge of the auger flighting. This gives a clean hole with a flat bottom. If the holes are made 7 inches deep, the top ring of the side ledges with holes are in contact with the surface of the soil and the rest are below the surface. With the ring of loose soil around the holes, and with rain, soil will infiltrate back around the container and fill any voids. Augering works best if the containers are spaced roughly 2 to 2.5 feet in the row and the rows are 6 feet apart. I have also modified a single shank lister plow for installing 5-Gallon Grounders™. This was accomplished by cutting off the 2 sides so that it was about 11 inches across. Then, I welded flat steel plated to both sides. When pulled through the soil, it leaves a trench at the depth you choose and about 11 ½ inches wide. The 5-Gallon Grounder™ fits into the space nicely. After all of the containers are placed in a row, soil is pushed back into the trench between the pots. This works well if the containers are spaced roughly every 2 feet in the row and the rows are 4 or 5 feet apart.

No. The bottoms of the round and the square one gallon containers as well as the 3-Gallon containers are designed to be placed on ground cover cloth or plastic. Air-root-pruning is accomplished by air circulation around the containers at both sidewalls and drain holes at the sides of the bottoms. The only situation I have observed where air-root-pruning on the sides was marginal was where the square 1-gallon containers were placed snugly together and were more than 6 containers wide. Some roots in the center of the blocks had roots extending ½ outside the openings. If you use the square 1-gallon containers in blocks greater than 5 or 6 wide, leave a small amount of space between containers for air circulation.

It depends on your location and growing conditions. If your containers are out of doors in full sun with moderate air movement, then 10 to 12 inches is probably sufficient. If you are growing seedlings in a structure where air movement is limited, you may need to have your wire benches 16 – 24 inches above the floor. If you are seeing roots, even just small tips of roots extending a short distance out of the air-root-pruning openings, you do not have sufficient air circulations or height above the soil surface for your location.

We suggest that harvested trees in Knit Fabric containers be placed above ground and NOT mulched in. The main reason mulching is done is to kepp B&B trees from blowing over and to aid the tree, since 95% or more of the roots were lost in harvesting. If you place the trees grown in Knit Fabric containers above ground, the flat bottoms help them stand erect and if you do not mulch, you get air-pruning around the outside. Once above ground, and when not mulched in, with the first flush of growth the tree will produce another cycle of root branching within the rootball which will also be air-pruned. The primary reason for moving trees grown in Knit Fabric containers into containers is appearance and ease of handling. Once trees are harvested and placed above ground, the Knit Fabric containers are unattractive. When placed in RootBuilder® or RootTrapper® soft-sided containers, the trees look great, especially in the white RootTrapper®, and are available to sell all summer.

For 1- and 3 gallon containers, there is no practical alternative to overhead sprinklers. Yes, they waste a lot of water, but the cost and complication of using spray stakes, etc. is not the answer. Drip emitters over the top of 1 gallon does not work, mostly because of the expansion and contraction of the poly lines and not getting the water where it is needed.