George's Current Ramblings and Readlings

Navigating Our New Gardening Weather

April 23rd, 2024

   When is it “safe” to plant the tomatoes and summer flowers?

Our frost dates are changing. It may be possible to get an earlier start to the season… but keep the row covers handy!

   That’s a question gardeners wring their compost-stained hands over every year at this time – especially the eager ones who don’t want to miss a day of potential frost-free grow time.

   Not that long ago, Harrisburg-area gardeners could rely on the long-held rule of thumb that the last frost of spring usually happened somewhere around early May. And so the word on the street was that you waited until after Mother’s Day to pull the trigger on the marigolds, petunias, tomatoes, and such.

   However, if you go by what’s been happening since 2000, that Mother’s Day milestone is outdated and in most years gives up two weeks or more of frost-free time.

   According to National Weather Service climate data from 2000 to 2023, the average last killing-frost date for the Middletown/Harrisburg area is April 11.

   Last spring, the Middletown/Harrisburg area had its last killing frost on April 9.

   You might be surprised at how early those dates are, but keep in mind that those are average and one-year figures.

   What can happen in any given spring is far iffier.

   That’s why gardeners – at least the cautious ones – still look to the all-time latest frost date when timing their planting of summer vegetables and annual flowers.

   In the Harrisburg area, that date is May 11 – or in other words, the Mother’s Day guideline.

   In the outlying regions to the north of Harrisburg, it’s still possible to get a rogue late frost into late May.

   The bottom line is that it’s a matter of how much risk you want to take before pulling the tender-plant trigger – or if you have enough sheets or floating row cover to cover those plants if you guess wrong.

   If you’re a data-driven person, the National Gardening Association has an interactive online tool that lets you type in your Zip code and then see what the odds are that the temperatures will go down to 32 degrees or below at various points in March, April, and May.

   And if it’s recent track record that you like better, the National Weather Service has a chart showing the actual last dates that temperatures went down to at least 32 degrees in the Middletown/Harrisburg area over the past 23 years.

   Here are those dates:

Award-Winning Plants of 2024

April 9th, 2024

   Organizations of growers, horticulturists, researchers, and other plant experts each year bestow assorted awards on what they believe to be the best of the best plants.

Some of the plants that have won 2024 awards.

   Some of these award-winners are new introductions. Others are under-known or under-appreciated oldies-but-goodies that deserve more use in home gardens.

   Here’s a look at plants that have won honors for 2024:

Pennsylvania Gold Medal

   A panel of experts assembled by the Pennsylvania Horticultural Society (best known for running the Philadelphia Flower Show) each year picks a half-dozen trees, shrubs, and perennials worthy of greater use in Pennsylvania landscapes.

   For 2024, two shrubs, two perennials, a small flowering shrub, and the first entry in a new category (edibles) made the Gold Medal grade.

Buttonbush Sugar Shack

   This is a compact and heavier-blooming version of a Pennsylvania native shrub (Cephalanthus occidentalis). Sugar Shack produces fragrant, round, white flowers in summer on plants that grow about five feet tall and wide. Fall-foliage color is copper-red along with round red fruits. It grows best in moist sunny to partly shaded spots.

Florida anise ‘Woodland Ruby’
Credit: Pa. Horticultural Society

Florida anise ‘Woodland Ruby’

   This variety of a little-known southern U.S. native shrub (Illicium) is cold-hardy to most of Pennsylvania and attractive for its long-lasting, summertime, mildly fragrant red flowers. ‘Woodland Ruby’ grows six to seven feet tall, is resistant to deer browsing, and does best in sun or part shade.

Japanese roof iris

   A little known form of Japanese-native iris (Iris tectorum), this perennial produces upright strappy foliage about 12 to 18 inches tall and bluish-purple flowers in late spring. Plants colonize to make a tight, deer-resistant groundcover. Grows in full sun to part shade.

Foamflower ‘Brandywine’

   This variety of our native foamflower (Tiarella cordifolia) is an ideal early-spring pollinator perennial with its short, white plumes in April and May. It does best in damp, shady sites but also tolerates the dry shade under big trees – and isn’t a likely target of deer.

Magnolia ‘Genie’

   ‘Genie’ is distinctive for its narrow habit – a tree that grows slowly to about 12 feet tall but only five feet wide in 20 years. It produces classic, large magnolia flowers that are purplish-red in color and that peak in late spring but appear sporadically throughout summer. This tree grows best in somewhat damp, acidic soil in full-sun to part-shade locations.

Asparagus ‘Millennium’

   The Gold Medal program’s first edible award-winner is this variety of asparagus that is fast becoming the flag-bearer in home gardens. ‘Millennium’ is a high-yielding asparagus with good flavor and green ferny foliage that turns yellow in fall. Plants grow three to four feet tall and perform best in full sun.

Phlox ‘Jeana’ is the 2024 Perennial Plant of the Year.

Perennial Plant of the Year

   Members of the Perennial Plant Association vote to honor one perennial plant each year that’s superior in terms of performance, low care, pest resistance, and multiple-season interest. The 2024 winner is…

Phlox ‘Jeana’

   ‘Jeana’ is a U.S.-native tall garden phlox that’s been a top-seller for years for its plentiful flowers, sturdy habit, pollinator-friendliness, and especially its resistance to the powdery-mildew disease that plagues so many phlox varieties.

   Flowers are fragrant and lavender-pink in color, peaking in mid-summer. Including the flower spikes, plants grow four to five feet tall. Best in full sun.

What to Do About Wacky Warm Weather

March 26th, 2024

   Another warm winter has faked the landscape into acting like we’re farther ahead on the calendar than we really are.

Ahead-of-schedule buds and blooms are more susceptible to this kind of cold damage than plants that maintain their winter dormancy longer.

   That’s not a problem if the weather course stays full steam ahead. So long as temperatures don’t nosedive in the coming weeks, the upshot is that we’ll simply have an early spring. Plants will bloom earlier, and growth will advance sooner than usual into a normal growing-season pace. No problem.

   The trouble is if the weather decides to back-track into traditional norms or less… or worse yet, yo-yo’s between abnormally warm and abnormally cold. Plants like sudden change even less than people.

   The way it used to work most years, plants stayed dormant long enough to protect themselves against early to mid-spring freezes. But when flowers and buds open early due to the kind of sustained warmer-than-usual temperatures we’ve been having in recent winters, they lose some of that protection.

   Open flowers or too-far-along leaf buds are much more susceptible to cold injury. Temperatures that they would have sloughed off while dormant can cause damage to this advanced growth.

   Sometimes a few degrees can make the difference.

   Smaller bushes can be draped overnight with a floating row cover or sheet to give a few degrees of protection in a frosty forecast, but there’s no good practical solution to help a 20-foot tree. (Orchardists run misters all night.)

   If the worst happens, cold-killed flowers will result in few or no fruits (on species that produce fruits and berries), while prematurely advanced leaf buds can result in browning around the leaf tips and margins.

   We’ve seen that happen several times in the last decade as our winters have warmed but early spring didn’t get the memo that the buds were beyond dormancy.

   Plants normally grow through these setbacks, but it’s a blow to that year’s performance.

   This wacky up-and-down stuff (not to mention even a single very cold snap in the middle of an otherwise warm winter) is also enough to cause browning on evergreens – especially broad-leaf ones like azaleas and boxwoods.

   If you’re seeing some brown, brownish, or even bare evergreens, don’t despair. They may not be mortally injured.

2024 Philadelphia Flower Show Reporter’s Notebook

March 11th, 2024

   The just-ended 2024 Philadelphia Flower Show was another typically wow event with its 75,000-flower main-entrance garden, billboard-sized floral map of the U.S., and floral “clouds” hanging from the ceiling.

The flower show’s Main Entrance garden had color every which way you looked.

   But among the blooming glitz was a lot of fascinating plant and gardening information. Here’s a sampling that filled this reporter’s notebook.

See George’s PennLive.com post with pictures on 14 of the coolest sights at the 2024 Philadelphia Flower Show

The show’s big buzz

   The U.S. Geological Survey Team (of all entities) had an eye-opening display on the importance of native bees, which are getting a lot of love lately for their pollinator services.

   Did you know Pennsylvania, Maryland, New Jersey, and Delaware, have 450 species of native bees, and that many of them look more like mini-houseflies than the lumbering bumblebees that most people envision when they think bee?

   USGS says two of the best things gardeners can do to help dwindling populations of native bees are: 1.) replace lawn space with flowering plants (especially native species), and 2.) drill 1/8-inch to 5/8-inch holes in dead wood around the yard to encourage nesting.

   For everything you’d want to know (and see) about native bees, check out USGS’s Bee Lab website.

“Speed dating” and the vanilla orchid

   Vanilla is the world’s second most expensive spice for good reason. (Saffron is number one.)

These are pods of the vanilla orchid drying.

   Not only is the vanilla orchid vine finicky about weather, it has only a 12-hour window of pollination, and it depends on one specific bee to do the deed.

   “Talk about speed dating for flowers!” Waldor Orchids pointed out in the signage on its vanilla orchid display.

   That super-specific requirement is why vanilla growers have to hand-pollinate flowers – one-by-one at the precise time – to induce the plants to produce the long, skinny bean-like pods that give us our beloved flavoring.

   Harvest time is also short and tricky, plus it takes two months of curing to ready the pods for processing.

   Vanilla is the only orchid that gives us edible fruits, says Waldor Orchids, which showed us 16 tripods of vanilla orchid vines growing in a tropical garden at the show.

The World’s First Purple Tomato

February 27th, 2024

   We’ve had purple- and dark-blue-skinned tomatoes for years now, but this month marks the arrival of the world’s first tomato that’s a true, dark purple throughout.

The Purple Tomato is purple throughout, not just at the skin level.
Credit: Norfolk Healthy Produce

   For now at least, it’s called simply The Purple Tomato, and it’s a bioengineered cherry-type tomato that gets its purple coloring from the genes of a purple snapdragon.

   That’s what makes this variety particularly ground-breaking – it’s the first time a genetically modified food crop is being marketed directly to consumers. Up to now, so-called GMO crops have been grown by commercial producers.

   Norfolk Healthy Produce, the California start-up that’s the sole source of The Purple Tomato, began selling seeds to home gardeners earlier this month. They’re priced at $20 for a pack of 10 and available only through Norfolk’s website.

   What remains to be seen is how well the idea goes over since a large chunk of the American product is leery about bioengineered/GMO foods.

   Although the U.S. Food and Drug Administration has found no ill effects from eating bioengineered foods, slightly more than half of Americans have GMO health concerns, according to a 2020 Pew Research survey.

   British biochemist Cathie Martin started work on The Purple Tomato 20 years ago by identifying a gene that gave a snapdragon its purple flowers. She then used a bacteria to insert the genetics into tomato plants.

   The effort got a green light last year from the U.S. Department of Agriculture.