 |
| Wind whipped plants 1/29/19 |
I only took one photo for this post because I really didn't want to be outdoors longer then absolutely necessary. It looks like the frozen tundra outside, and it feels like it too! We have a historical outbreak of cold occurring happening tonight. Some parts of Iowa will get colder then ever have before ( Being 100% serious) Places like Davenport would be one such place, they are forecast to get down to -30.F and the current record is -28.F. Here in Des Moines we could get down to -22.F. This is significant because if this temperature is actually realized it would be the coldest in 23 years. Some gardeners like myself wonder how this is going to effect the plants, so lets dive in. Des Moines is officially listed at plant zone hardiness 5b which means winter lows are supposed to be in the range of -10 to -15 below zero. Our low could get 7 degrees lower then that. You wont have to worry about that old Oak in the yard, or even that viburnum shrub. However it does mean some newer plants that have been available in the last 20 years like certain Japanese Maples, Boxwood, Evergreen Azaleas and Forsythia are at risk for getting cold damage.
The main concern automatically will be any plant that is truly exposed to the cold, if it has a part that is above the ground or snow. Certain spring-blooming trees and shrubs usually suffer the most damage. The reason for this is because the flower buds for many of our favorite blooming plants like Redbuds, Forsythia and Azaleas form in around late summer of the previous season and they remain on the plant throughout the winter exposed. It's known that flower buds are not nearly as hardy leaf buds and damage occurs when the temperature drops below a certain point so we end up loosing the floral display for that year. Remember though as mentioned leaf buds are hardier so the overall health of the plant will be just fine and they will still leaf out normally. This issue would only be expected with select newer plants because oldies like Crab Apples, Lilacs, Roses and Weigleas ect. have flower bud hardiness much colder.
The good new is we have 15" of snowcover which will be in our favor and may allow for some flowers to be spared, if any flowers on low branches are under snowcover currently they will be protected as well from the cold just like being under ground. They call this the snow-line. So it could be said that those shrubs will have flowers below the snow-line, provided we don't get more extreme cold later after the snow melts.
Besides the flower bud damage we could also see some leaf and twig damage on those marginal plants in the area as well. Some plants like Peach trees, Japanese Maples and certain Boxwoods may suffer some dieback but latent buds farther down the branches will allow these to recover. The worst case scenario if the plant you have is very marginal to Iowa and if you're like me and planted a Southern Magnolia the entire plant will die back to the ground. Dang! Was so hoping for a more mild winter to give it a chance to establish more.
With the snowcover any perennials or bulbs will be completely un effected, so no worries there!
To shed at least some light on the possibility of damaged plants I found a short list of some plants I've noticed in the past are more susceptible to damage from cold. The research came from University of Minnesota because this region has some of the same plants as us and endure the temperatures we are expecting on a normal occurrence. However in the end we wont truly know the extent of the damage until spring arrives and things start to leaf out. Keeping fingers crosses it to a minimum! Also check out the plants below the damaged list for some varieties that are hardier to our area, it just may solve the cold problem all together, at least as far as plants are concerned.
Des Moines Airport Official Temp as of 6:54AM -20.F
Dwarf Korean Azalea 'Poukhanense Compacta' Flower buds significantly damaged at -18.F
Large Leaf Rhododendron; Flower buds damaged at -18.F
Azalea 'Girard Series' Flower buds destroyed at -8.F
Forsythia 'Lynwood Gold' Flower buds destroyed at -7.F
Peach Trees; ( Certain types ) Flower Buds Destroyed, Twig Damage or killed at -20.F
Redbud Tree; Flower buds destroyed in Minnesota at -23.F
Rose of Sharon, Some twig damage at -16.F.
Boxwood 'Winter Gem' Severe winter burn at -20.F
Cold Hardy varieties for Iowa
Large Leaf Rhododendron 'roseum elegans' Hardy to -25.F
Rhododenron PJM Evergreen Hardy to -30.F
Dwarf Rhododendron Rambo Hardy to -25.F
Forsythia New Hampshire Gold Flower bud hardy to -30.F
Peach 'Reliance' Hardy to -25.F
No comments:
Post a Comment