Hard Freeze Hits the Mid-Atlantic and South—Protect Spring Blooms

After weeks of warm weather during which temperatures reached well into the 60s and 70s in parts of the South, the region is now facing a St. Patrick's Day hard freeze. Forecasters are projecting temperatures to drop into the mid to upper 20s aver the next couple of days from Virginia through the Carolinas and down to Georgia, threatening shrubs and plants that have already awakened and started blooming.

While plants that are still dormant are safe, shrubs that have already awakened, including hydrangeas, azaleas, and forsythias, are in danger. These shrubs face the threat of losing their buds and blossoms to freezing temperatures, ending any chance of them flowering in the spring and summer. If you want to save those blossoms from frost damage, you need to act now. 

Related: When to Fertilize Your Lawn After a Brutal Winter—Timing Is Everything

How Does Frost Impact Blooming Shrubs?

Frost can cause everything from cosmetic damage to total devastation for shrubs that have already awakened from their winter dormancy. A hard freeze can destroy new buds and blooms, turning them into brown mush. And if sap is already coursing through their steams, sub freezing temps can even destroy the entire plant. Hydrangeas, azaleas, and forsythias are at particular risk as warm weather has already awakened these shrubs from dormancy.

Hydrangeas

Hydrangeas have already begun sprouting leaves on the tips of stems. Big leaf varieties of hydrangeas are particularly susceptible to freeze damage. When a late hard freeze hits, it can kill those new leaves and destroy the flower buds. When that happens, you can forget about the plant producing those large beautiful flowers hydrangeas are prized for. The plant won’t recover and produce blooms until next year.  

Azaleas

Thanks to warm late winter weather, Azaleas in the transition zone and parts of the South have already come out of dormancy and have begun blooming. As with hydrangea, a hard freeze can freeze flower buds, which turn brown and mushy and fail to flower, depriving your yard of those dazzling whites, pinks, and reds that azaleas produce in the spring. A hard freeze doesn't just threaten those blossoms but also the entire plant. If the sap has risen in the stems, a hard freeze can also cause branches to split and die back. 

Forsythias

If you live in the transition zone, then forsythias are already in full bloom. Unfortunately, a hard freeze will turn those blooms into brown mush. Luckily, forsythias are hardy enough that the freeze likely won’t do any additional damage and the plants should leaf out as they normally would when warmer weather returns.

Related: Look for This Winter Damage To Your Lawn

How to Save Your Shrubs’ Blossoms

If your shrubs are small enough, you can protect them from frost and preserve their buds and blooms for beautiful summer colors. Here’s how:

• Water the plant. Well-hydrated plants will recover from the freeze faster (If there’s rain in the forecast as that cold front moves through then watering may not be necessary. 
• Cover the plant. Cover the plant with sheets, burlap or freeze blankets to protect it from the cold temperatures. 
• Add mulch. Add a base of 2 to 4 inches of mulch to protect the roots from freeze damage.

How to Treat Freeze Damage

If you’re shrubs do suffer freeze damage, then take these steps to help it recover. 

• Don't prune. If your hydrangea does suffer freeze damage, DON’T trim them back immediately. That dead foliage can serve as insulation that protects new growth from further freeze damage. Instead, wait until the plant begins showing signs of new growth or your well past the threat of frost.
• Delay fertilizing. While it may seem like fertilizer can help damaged shrubs to recover more quickly, it can actually cause harm than good to already stressed plants
• Asses the damage. You can determine how much damage your hydrangeas or azaleas have suffered by conducting a scratch test. Use your finger nail to scratch away bark on the branches. If it’s still green underneath the bark, it's still alive.