CENTRAL INDIANA GARDENING ALMANAC

The purpose of this almanac is to provide a record of important recent statistics and events that relate to gardening and natural history. Occasionally I will note an upcoming event that is certain or at least strongly suspected to occur, but not long-term weather predictions as that is malarky (see Chapter 12 in my book for more specifics and become familiar with the Law of Independent Events). Historical norms no longer exist and we should expect radical fluctuations especially during the winter to spring and fall to winter transitions as global warming continues. As gardeners, we should be most concerned with the extreme and abnormal conditions rather than the averages. The observations are from Marion County (IN) but more broadly applicable, and all temps are Fahrenheit. As always, local variation is to be expected, and the variation will sometimes be pronounced. The years as I define them here are truncated by season rather than calendar because from a gardening perspective it seems logical that winter should include the preceding Dec; i.e., Dec + Jan, Feb . . . thru November. Lastly, know that the condition of your plants may be as much or more the result of what happened previously and a cumulative and multi-factor response; likely also impacted by whether or not established (i.e., how long ago planted) and if already stressed.

 

GENERAL OBERVATION EMPHASIS

  • Rapid temperature drop, esp. if not primed

  • Long dry or wet period

  • Max summer high & Overall hotness of summer

  • Max winter low (by season*) & Overall coldness of winter

  • Long cold winter period, esp. if windy

  • Dormancy breaking warm period late winter/early spring

  • Outside or regional event that affected climate (e.g., El Niño, volcanism)

  • Late spring frost/freeze and/or early fall frost/freeze

  • How growing season was affected

  • Prevalence of disease(s) or infestation(s)

  • Autumn leaf color and drop

  • Seasonal aberration(s) & Special occurrence(s)

 

FOR COMPARISON (average for past 45 years): 

    last spring frost/freeze (32°) Apr 17 - range 56 days

    first fall freeze/frost (32°) Oct 19 - range 44 days

NOTE: these events rarely if ever fall on the "average day" and only about 1/4 the time within the week surrounding the "average"

 

2020 - very mild winter, max low 2°and only briefly; setup for Apr 18 last frost/freeze (would have been the first time in 45 years that it was on the current average date) then a late vortex, 28° for several hours on May 9 (only the 6th May freeze during last half century); most affected plants - oriental maples (esp. red weeping cultivars), ginkgo, arborvitae (bronzing of some parts), irises (causing some to bloom in early Nov); 3-week dry spell in early June and longer period late Aug into Oct (nearly 60 days with only trace precipitation); few lightening bugs, moderate number Japanese beetles; prolific year for large asteraceous plants, e.g., compass plant; sparse cone production on conifers and, as I previously suggested, the phenomenally heavy cone production in 2019 was indicative of stress as some of the plants presented damage or died in 2020; almost no black walnuts after a bumper crop in 2019 and few sweet gum balls; some species/specimens damaged by the May 9 freeze may show long-term negative effects (somewhat tied to potential stress leading into 2021 growing season); 32° on Oct 16 and 28° on Nov 2, but growing season was only partially ended (many temp sensitive plants were not killed); early, prolonged and late fall color made somewhat less impressive by the lingering effects of the late spring freeze; typical ginkgo one-day leaf fall heavily impacted by a freeze/frost event and high wind, still had partial fall Nov 9 but primary drop occurred Nov 14 with temp of 27° and high RH; unusually warm early Nov, 77° on Nov 10 but was only 8° one year earlier; NOTE: 2021 will be emergence of Brood X of 17-year periodic cicadas which will have profound effect on new growth of many woody plants many of which already will be stressed from the May freeze (see maples above) and the late summer drought, those properties promoting birds may be somewhat less affected by cicada ovipositing due to predation (for more specifics on the cicada see Kritsky’s 2004 book, Ind Acad Sci publications) my April rant will highlight the emergence

2019 - very mild early winter thru mid Jan (lowest 15° in late Jan 15, rarely below 20°) then two short duration polar vortices, the first 2° (Jan 15) the second in the late Jan (30) -11° but 73° warmer 4 days later (Feb 3); 45° drop (59-14) in 14 hrs Feb 7; wet cool spring; first dry spell 1st week of June then continuously wet until last week of June; moderate spring and early summer temps; very dry Sept; do not remember a year with more cones on conifers (conditions did no seem problematic but I suspect stress induced reproduction); Nov 1 ginkgo fall (but fell green); super early cold (8° Nov 11) with plants not yet dormant, lots of marcescence

 

2018 - severe early winter (Jan), winter burn, max low -1°; no extended dry periods during the year; not exceptionally hot; horrible population of Japanese beetles; early cold spell (mid Nov) temp suddenly in the teens killing many leaves on stem before normal senescence (normal shutdown interrupted); short growing season; Nov 9 ginkgo fall

 

2017 - mild winter; early spring, early last frost; off cycle emergence of 17-year cicadas; lots of Japanese beetles & lightening bugs; high rainfall spring early summer; dry late summer/fall; lots of foliar fungal diseases; mild summer temps (fall in summer); great year for solanaceous plants; Oct 26 first frost/freeze; fall flowering PJM Rhodo ‘Elite’, Forsythia ‘Courtisol’; Nov 10 ginkgo fall

 

2016 - mild winter; ample rainfall; lots of foliar fungal diseases; lots of Japanese beetle & lightening bug; flooding and wind damage late August; long growing season (late frost); cool wet fall; sudden dramatic temp fall in late fall, affected several woody perennials and evergreening; 1st frost Nov 9; ginkgo fall not on a day but spread over a week

 

2015 - few Japanese beetles or lightning bugs; cool wet fall; Nov 9 Ginkgo fall