Friday, February 24, 2017

Winter Warmth Woes for Plants


While 65 degree winter temperatures in Chicago, day in, day out, are cause for jogger jubilation this weather is not doing most of our plants any favors. Our perennials, bulbs, shrubs and trees are being set up for a potential world of hurt. A notable exception is the lovely, naturally early-blooming witchhazel pictured above.

May I set the stage? December was seriously cold. The ground froze early and we had good snow cover to keep it frozen. Great. Now we've had less than 1" of snow in the new year. The soil surface has thawed. We've had minimal rain to provide moisture for roots. Is there anything we can do to lessen the potential damage to our plants? For what it's worth, here's my take on the situation.

Not ready for prime time
Bulbs
Unfortunately, bulbs are making an early above-ground debut. This is most apt to happen in unshaded south or west-facing exposures against buildings. The reflected heat has warmed the soil and led bulbs to believe it's time to rise and shine. Bulbs have built-in insulation mechanisms so leaves and unopened flower buds can tolerate very cold temperatures without damage. Open flowers would be subject to freeze damage. In other words, we're okay for the moment.
What to Do: If you want to be proactive apply an organic (I love leaf) mulch after the soil surface freezes again to keep it frozen to try to slow the bulbs down. Yes, that is an optimistic assumption.

Perennials
If planted in the past year perennials should be checked for "frost heaving". That is, the edges of the root balls would be 1/2" or more above the surrounding soil surface. Existing partially above grade these roots are subject to temperature and dehydration damage. Such plants are likely to pass on.
What to Do: GENTLY put a foot on either side of the EDGE of the root ball and try to push back into the ground. If dry, water those plants, then (leaf or compost) mulch when the surface refreezes. Remember, mulch roots, don't bury the crown (center) of the plant.

Water
Check plants, especially newly planted evergreens or plants in containers (ex: boxwood or Alberta spruce) for moisture. Dehydrated = damaged, dying or dead.
What to do: If the top inch or so of soil is dry, soak. When the soil freezes again consider applying mulch.

Water and apply Wilt-Pruf to crispy critters
Evergreens
Do you have broadleaf evergreens (rhododendron, azalea, holly, boxwood) in open, sunny windswept areas? Are they dry? If yes, did you water them?
What to Do: While temps are above 40 degrees F. consider applying an antitranspirant spray, Wilt-Pruf for example, to the underside of the leaves to reduce potential dehydration damage for the rest of the winter.

Tree wrap helps to prevent ugly cracks
Frost crack
Frost crack is a nasty symptom, occurring primarily on smooth-barked trees. If there's a prolonged period when trees are subjected to temps above freezing during the day, then dramatic drops at night, the expansion and contraction of the bark creates pressure points on the (again) south or southwest sides of the trunks. When the tree starts growing those pressure points may open up creating wounds - sometimes superficial, other times exposing deep fissures into the heartwood. Young (under 6" in trunk diameter): maple, honeylocust, sycamore and linden are most at risk.
What to Do: When the trunk surface is dry you might consider the use of the corrugated paper tree wraps or burlap to shade the trunk. Remove ASAP in the spring (mid-March).

Deer
Just because there's no snow cover doesn't mean our yews and arborvitae have a forage-free pass. On the contrary, I was inspecting my garden last week and saw 2 androgynous whitetails belly-high in the neighbors' yews, grazing. Two ear-splitting whistles later they were bounding down the street for a more relaxed dining experience. Very satisfying (for me).
To do: Consider draping the black mesh "deer netting" over yews or around arbs to exclude marauding deer. The netting isn't visible and really is a very effective deterrent. Or spray vulnerable evergreens with the repellent Plant-Skydd. It's also very effective when sprayed on emerging bulbs and dayliliesDeer just hate it!

Now the best we gardeners can hope for is a deep, soaking rain followed by a quick return to sub-freezing temps until the time when spring should really arrive.                



















Friday, February 10, 2017

Mid-Winter Houseplant Blahs

We're finally on the "backside" of winter. For those of us not winging off to a tropical island between now and spring that's an important psychological milestone, just as it is for our houseplants. Even the word "houseplant" sounds winter-weary and less than exciting - kind of like "leftovers". Just for today let's call houseplants indoor tropicals (ITs), and maybe they'll seem fresher.

This is about the time our ITs may be showing their ennui by exhibiting "symptoms". Certainly, they're as tired of short days with constant cloud cover and and low indoor humidity as we are. And that presumes we're watering correctly in response to these imperfect conditions. So, assuming they have good personal hygiene and are otherwise free of livestock and pestilence, here's an abbreviated troubleshooting guide. The caveat- "Probably" should probably be inserted in front of each bullet point. Why? Because it's as likely a combination of factors as a single one causing IT malaise in your collection.

Potato chip-crispy spots or lesions on leaves: Underwatering

Lesions that are soft, dark brown or water-soaked: Overwatering 

Leaves are curling (either upward or under): 
  1. Chilling (too close to a drafty window or door to the outside, room colder than the plant likes) and/or
  2. Overwatering
Leaf drop: 
  1. Plant subjected to temperature extremes (too high, too low) for some period of time
  2. Someone in charge of watering that let the plant go bone dry for weeks or months, and it's not a forgiving cactus or succulent?
  3. Is it a new adoptee that was just brought home from the greenhouse? In other words, has it been used to higher light and you've featured it in a window-less, light-less room resembling the inside of a sarcophagus?
  4. Did it get chilled on the way home by being outdoors unwrapped? Did it sit in a car while you shopped-'til-you-dropped for hours and the car temps got dangerously low?
Just tossin' these ideas out there. These aren't accusations, we're just trying to get to the root of your ITs problem (ignore unintended horticultural pun).

Lower leaves turn yellow and drop:
  1. If it's just one leaf and it's the very oldest (lowest on the stem) that may be okay. Leaves don't live forever. Plants naturally shed old leaves that are shaded by the upper portion of the plant.
  2. Multiple leaves yellow? Has it been overwatered? Too much water, too frequently?
  3. Chilling
  

Leaf ends or edges brown, brittle:
  1. Humidity just too low for the plant (by far the most common reason)
  2. Erratic watering- plant is alternatively wet and/or dry
  3. Like Goldilocks, room "too hot", "too cold", never just right
  4. Fertilizing frequently while plant is on winter growth hiatus, and therefore not utilizing nutrients. We call that "burn"
Lower leaves turn brown (dry) and drop: 
  1. Just not enough light for the species you're trying to grow
  2. Room excessively hot and dry
  3. Plant regularly underwatered
Individual leaf stems (petioles) or entire stems soft and mushy:
  1. Overwatered on a regular basis and/or
  2. Left standing in a water-filled saucer or pot with no drainage hole frequently and for long periods of time
White residue on soil surface:
  1. Fertilizing frequently all winter long? S-T-O-P now. Those fertilizers salts are accumulating because the plant is not growing and therefore not using them OR
  2. Using hard water with high salt levels
Plant not producing new growth:
  1. It's winter, full of short, cloudy days. Unless you have a greenhouse or full-length south or west-facing windows to maximize light to perhaps coax some growth from your plants, relax. This is normal for our winters. New growth should start peeking out as we approach spring.
Keep chanting the mantra, "It will be alright. It will be alright. It will..."      

          














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