Do you have to remove all the roots from a shrub?

When transplanting a shrub from one location to another, a common question that arises is whether you need to remove all of the roots before replanting it. The answer depends on several factors, including the size and type of shrub, the transplanting method being used, and the goals for the shrub after transplanting.

Quick Answers

Here are some quick answers to common questions about removing roots when transplanting shrubs:

• You generally don’t need to remove all the roots. Pruning some of the roots is often sufficient.
• Removing about 1/3 of the root ball is a good rule of thumb for most shrubs.
• Pruning roots stimulates new root growth in the transplanted location.
• Excessive root removal can shock the plant and set back its establishment.
• The amount of root removed depends on factors like shrub size, transplant methods, soil conditions, etc.
• Removing more roots may be necessary with pot-bound container plants or soil-bound shrubs.
• Always prune damaged, diseased, circling, or tangled roots.

Root Pruning Goals

When transplanting a shrub, the goals with root pruning are:

• Reduce the root mass so it will fit the new hole or container.
• Stimulate new feeder root growth in the transplanted location.
• Remove any problem roots that may hamper establishment.
• Retain enough roots to support the shrub’s foliage and prevent transplant shock.

Finding the right balance between these goals is key for success. Too little root pruning won’t stimulate new growth, while too much can starve the shrub of needed water and nutrients.

How Much Root Pruning is Needed?

As a general guideline, pruning away about 1/3 of the shrub’s root ball is sufficient in most cases. However, the exact amount can vary based on several factors:

• Shrub size – Large, mature shrubs can handle more root loss than smaller, younger ones.
• Rootbound plants – Those grown in pots or with circling, matted roots require removing more of the root mass.
• Transplant methods – Bare root and ball-and-burlap transplants need less root pruning than containerized or in-ground shrubs.
• Soil conditions – Excessive or poor soils may require pruning more roots to encourage new growth.
• Time of year – Pruning less roots when the shrub is active in spring/summer can help prevent transplant shock.

Also consider the shrub’s species, as some are more sensitive to root disturbance than others. When in doubt, err on the side of less root pruning rather than more.

Root Pruning Methods

Here are some common methods for pruning shrub roots prior to transplanting:

• Use hand pruners, loppers, or saws to cut back large, woody roots. Make clean cuts rather than tearing.
• For fine, hair-like roots, you can simply prune them back with hand pruners or even a sharp knife.
• Shave down the sides of the root ball with a spade to reduce width and depth.
• For pot-bound shrubs, make vertical slices from top to bottom through the root mass using a knife.
• Untangle, straighten or prune away any roots that are circling or tangled.

Try to retain some larger woody roots as well as the fine hair roots when pruning. Cutting the root ball into sections like slices of pie is also an effective technique.

When to Avoid Root Pruning

While root pruning is commonly done when transplanting shrubs, there are some cases where removing roots is not advised:

• When the shrub is small or weak, pruning away too many roots can overload it.
• In times of heat stress or drought, root loss can exacerbate moisture problems.
• Right before or during flowering, as root loss can sacrifice buds and blooms.
• With evergreens like pines, hemlocks, or spruces, minimal root pruning is best.
• When transplanting in very poor or compacted soils, retaining more roots helps establishment.

Additionally, refrain from excessive root pruning that leaves just a stub or removes over 50% of the root mass. Gradual pruning over multiple seasons is better for the health of stressed or sensitive shrubs.

Caring for Root-Pruned Shrubs

Proper aftercare is critical for root-pruned shrubs to recover and establish in their new location. Here are some tips:

• Water thoroughly after transplanting and monitor soil moisture closely.
• Stake or support shrubs that may topple due to reduced roots.
• Apply mulch around the base to retain moisture and reduce weeds.
• Fertilize sparingly until new growth is evident.
• Prune back the top growth if the root system was significantly reduced.
• Allow the shrub time to establish before major pruning or shaping.

With attentive aftercare, most shrubs will successfully establish within 1-2 seasons after being transplanted and root pruned.

Signs of Excessive Root Pruning

Be on the watch for these signs that you may have removed too many of the shrub’s roots:

• Wilting, drooping, or curling leaves
• Loss of leaf turgor and dull, grayish foliage
• Dieback of stems and branches
• Leaf scorching or browning at the margins
• Failure to leaf out or grow new shoots
• Plant collapse or death

If you notice these issues shortly after transplanting, take corrective measures like watering more frequently, temporary shading, mulching, and pruning back damaged growth. Preventing excessive root loss in the first place is the best approach.

Special Cases for Root Pruning

Certain types of shrubs have special considerations when it comes to root pruning for transplants:

• Evergreens – Take the minimal root pruning approach, only removing obviously problem roots.
• Heavy bleeders (maples, dogwoods, etc) – Make clean cuts and seal wounds to prevent sap loss.
• Fall transplants – Prune less roots to reduce transplant stress going into winter.
• Mass plantings – Prune aggressily at the nursery before installation for uniformity.
• Hedge transplants – Prune the entire root mass by 1/2 to encourage dense regrowth.

Getting to know the specific needs of different shrub species takes experience and experimentation. When trying a new plant, start conservatively with root pruning.

Proper Root Pruning Technique

Follow these steps for the best results when root pruning shrubs:

1. Water the shrub well the day before pruning roots.
2. Prepare the new planting hole or container before pruning.
3. Carefully excavate around the root ball to expose the roots.
4. Prune away any damaged, diseased, circled, or congested roots first.
5. Prune back thicker woody roots using loppers or saws.
6. Thin out fine hair roots using pruners, knife, or shaving down the root ball.
7. Prune any girdling or tangled roots growing across the root ball.
8. Prune away about 1/3 of the overall root mass.
9. Replant quickly after root pruning and water in well.

Follow these steps precisely for the highest transplant success rates. And remember, less root pruning is generally better than over-pruning the roots.

Conclusion

Root pruning is often advised when transplanting shrubs to encourage establishment in the new location. But removing all of the roots is rarely necessary. Pruning away approximately 1/3 of the root mass strikes a good balance for most shrub transplants. The exact amount to prune depends on factors like shrub species, transplant methods, soil conditions, and time of year. With proper aftercare, most shrubs recover well from judicious root pruning. Just take care not to overdo it, as excessive root loss puts significant stress on the transplant. Adjust your root pruning approach based on the needs of each unique situation for best results.