What to Do if a Grapefruit Tree Was Exposed to Freezing

Monitoring and Short-Term Care

• Perhaps the most important aspect of caring for a freeze-damaged grapefruit or other citrus trees involves monitoring the tree to determine the extent of the injury, which may not become clear for weeks or even longer following the freeze, and timing treatments. Even where the extent of the freeze damage appears obvious, pruning stimulates a flush of new growth especially vulnerable to cold injury. Dead branches left on the grapefruit tree also, to some extent, protect still-living areas of the canopy from cold temperatures. Until all danger of frost and freeze has passed, only water the soil around the grapefruit if it is dry; too much water can encourage new growth prematurely. Wait to apply fertilizer until new growth emerges. If significant dieback occurred, adjust the quantity of fertilizer applied to reflect the proportion of the original canopy that remains.

Where Fruit are Present

• If fruits that are nearly ready to pick are present on the cold-exposed tree, inspect the fruit to see if any action is required. If the fruits did not freeze, you can leave them on the tree and pick them as you normally would. If the fruits froze, you still can pick the fruit within a few days of the freeze and use them for juice. Damaged fruit feels spongy, not firm, and eventually will begin to dry out. Fruits located in the protected interior of the tree are less likely to be damaged by a freeze than fruits at the outside.

Pruning

• If possible, wait to prune the injured grapefruit tree until after a flush of growth occurs in the late spring or early summer, making it clear which branches were killed. Use clean, sharp pruning tools to remove dead wood. Make every pruning cut into living, healthy wood just above a vigorous shoot or junction with a living branch. More extensive dieback caused by the freeze may continue to become apparent for several months after new growth begins, tending to become noticeable when heat or drought stress occurs.

Painting the Trunk

• If leaf loss following a cold event is significant or you had to remove a lot of dead branches or a few major limbs, the trunk and scaffold branches of the grapefruit tree are likely exposed to a greater amount of sunlight than they previously were, leaving them vulnerable to sunburn. To avoid problems with sunburn, wrap the trunk and exposed parts of major limbs with light-colored trunk wrap, whitewash them or paint them with diluted white or light-colored latex paint.

Severe or Extreme Freeze Damage

• Where an extreme freeze or extended period of low temperature occurs, or the grapefruit tree is particularly sensitive, dieback that extends well beyond fruit or foliage may occur. In this case, you may have to cut back most of the tree's canopy to make your corrective pruning cuts into living tissue. If the entire aboveground portion of the tree was killed, the root system still may be alive and will send up new shoots if you cut the tree down to ground level. For grafted specimens, however, this typically is undesirable, as the growth that will appear is from the rootstock species. You also can graft scions from desirable specimens onto the new shoots that emerge to take advantage of the existing root system.