More Forbidden Plants, a Nursery Makeover, and Purple Tomatoes: The Latest Gardening News

Let’s catch up on some plant and garden reading chicks this week while we wait for next month’s pea plant milestone…

Invasive plants prohibited

Five species of honeysuckle are the latest plants to be banned for sale in Pennsylvania after being classified as harmfully invasive and on the state’s Noxious Weed List.

The state Department of Agriculture’s Controlled Plant and Noxious Weed Committee voted last month to ban the Amur, Morrow’s, Tatarian, Bell’s and Standish species of honeysuckle from sale in Pennsylvania. (Note that this does not include native trumpet or coral honeysuckle cultivars such as ‘Alabama Scarlet’, ‘Major Wheeler’ and ‘Cedar Lane’ or other honeysuckle species and hybrids such as ‘Gold Flame’, ‘Serotina’, ‘Scentsation’, ‘and’ Winchester.’)

The committee also voted to add starwort — an alga that can clog waterways and affect fish breeding areas — to the list of noxious weeds.

The additions bring the Class A list to a total of 20 plants (those that can potentially be eradicated) and the Class B list to a total of 38 (those that are too widespread to be eradicated). Most of the plants on these lists are what most people consider “weeds,” such as Japanese knotweed, thistle, poison hemlock, kudzu, giant hogweed, and so on.

The latest action continues a government crackdown on invasive plants that began in late 2021.

Since then, Pennsylvania has banned the sale of several popular landscape plants, including flowering (callery) pear trees, burning bush, common and glossy buckthorn, chocolate vine (Akebia), four species of privet (Japanese, Rand, European and Chinese) and Japanese barberry (excluding four sterile varieties in the WorryFree series: Crimson Cutie, Lemon Cutie, Lemon Glow and Mr. Green Genes).

  • Read more about previous plant bans

Although gardeners are not required to remove prohibited plants from their gardens, the Ag Department recommends their removal to stop continued, unwanted seeding into the wild.

Many of the newly banned landscape plants will be withdrawn from sale.

Japanese barberries, for example, will be banned from October 3 this year, while flowering pears will be banned from February 10, 2024.

The Burning Bush and the Four Forbidden Privets have a grace period until January 10, 2025.

Honeysuckle and star alyssum will be banned 60 days after the Department of Agriculture’s measures are published in the Pennsylvania Bulletin, which is expected to happen early this spring.

Although the above plants can be sold by the above deadlines, the Ag Department discourages gardeners from purchasing them, instead recommending native or non-invasive alternatives.

  • Read George’s column on native alternatives to invasive plants
Redesign of Hershey's nursery

Hershey Gardens is almost done redesigning its 20-year-old nursery.

Hershey’s Children’s Garden facelift

Hershey Gardens’ 3-acre nursery is almost complete with renovations, and the 20-year-old interactive garden is expected to show off its fresh look by spring.

“We are awaiting delivery of some additional items that need to be installed and replaced,” says Gardens spokesman Anthony Haubert. “Once that happens, we should be done with all the renovations. We aim to be ready by late March or early April.”

The work included new plants, new cedar for the bird screen, repointed stonework, new raised beds in the hoop house, and fresh paint throughout.

In the works are a remodeled treehouse (redesigned to a rainforest theme with a thatched roof, cocoa pod accents, and a monkey bar), a new boat play structure, and a new wooden bridge in the River Banker’s picnic area.

The early spring end date coincides with the time when gardeners are getting nervous about Hershey Gardens’ massive spring bulb display.

Flowering bulbs usually last from mid-April to early May, depending on the weather of that time of year.

“It’s always a guessing game as to when that will be,” says Haubert. “We’re telling people who inquire – and we’re getting a lot of inquiries from mid-March onwards – to check our website and social media pages for updates on the tulip bloom.”

Last fall, employees planted almost 26,000 new flower bulbs. This included 1,500 new daffodils around the conservatory and the remaining different types of tulips around the conservatory, in the nursery and most in the seasonal display garden.

Also over the winter, Hershey employees replaced overgrown potted palms in the atrium of the main entrance to the conservatory with more compact foxtail palms.

sedge of the wood

This sedge, known as the forest sedge, was the top performer out of 70 species and cultivars in the Mt. Cuba Center’s new trial.

The best sedges

The Mount Cuba Center in Delaware has just released the results of its latest plant experiment – this time examining 70 different species and cultivars of sedge (Carex) over four years of evaluation.

Sedges are grass-like perennials that have become fashionable lately, not least because deer rarely feed on them.

“(Sedges) are quickly becoming favored by homeowners and gardeners alike, thanks to their beauty, utility, and overall minimal maintenance requirements,” says Sam Hoadley, director of horticultural research at Mount Cuba. “The diversity of the genus is matched only by the wide range of habits in which they grow. From shady wetlands to coastal dunes, you can find a (sedge) to grow and thrive.” Many sedges are native plants of the United States, and as the Mount Cuba trial report shows, most can even be used as a mowable substitute for traditional lawn grass.

Mount Cuba tested the 70 sedges in both shade and sun on average garden soil. In the most recent year of the evaluation, staff mowed the sedges every two weeks to assess their potential as a turf substitute.

The foot-high, green-leaved native woodland sedge (Carex woodii) was the test winner of the study. Hoadley says it excels in both sun and shade, offers a carpet of straw-colored blooms from April to May, and was the best-performing mowable sedge of the trial.

The remaining top 15 sedges in the trial (after woodland sedge) were: Cherokee sedge (Carex cherokeensis), brome (Carex Bromide), Hayden sedge (Carex haydenii), erect sedge (Carex stricta), Emory’s sedge (Carex emoryi), long-billed sedge (Carex sprengelii), Pennsylvania sedge (Carex pensylvanica), Pennsylvania sedge ‘Straw Hat’, Muskingum sedge ‘Little Midge’, White-tipped sedge (Carex albicans), Jacob’s sedge (Carex jamesii), Muskingum sedge ‘Oehme’, fringed sedge (Carex crinita), Leavenworth sedge (Carex sourdough) and plantain sedge (Carex plantaginea).

over-harvest ramps

Ramps are bulbous native plants that have recently become foodie favorites.

Loot the ramps

Ramps — those bulbous plants that often grow wild in Appalachian forests — have become so popular in foodie circles of late that concerns about their over-harvesting are growing.

A new study from Penn State shows that ramp colonies would recover much better if ramp collectors waited a month longer to harvest.

Also known as wild leeks, these strappy-leaved plants have been popular in the region for hundreds of years for their garlic-like aroma and onion-like flavor. Both the leaves and the underground bulbs are edible.

The demand – and value – for ramps has skyrocketed in recent years as they have become favorites of foodies and restaurant chefs. The price increases have led to a sharp increase in wild colony gathering.

Enter Penn State, which has been exploring ways to preserve this “key cultural resource.”

“Even with modest harvests from ramp fields, it can take years and years for these plant populations to recover,” said Eric Burkhart, associate professor of ecosystem science and management at Penn State.

Penn State researchers found that shifting peak harvests by a month from the usual harvest time of March 1st to May 30th can significantly increase crop yields.

“If collectors just waited a little longer,” says the study’s lead researcher, assistant professor of biology Sarah Nilson, “they can actually collect the same weight of ramps with less effort because the plants are taller.” We’re going to try to promote this little adage: Fewer ramps per pound is more ramps in the ground.”

Nilson adds that it’s best to wait until the plants have developed at least three leaves before harvesting.

Ramps are perennial plants that can also be grown in home gardens, although they do best in moist, shady spots—unlike traditional bulbs and garlic.

Big purple tomato

British plant developers have produced a tomato with purple flesh and skin.

Purple Tomatoes

Gardeners have long been able to grow tomatoes with purple skin, but a pair of British researchers have developed the world’s first cherry tomatoes, which are deep purple throughout.

The purple tomatoes have been genetically engineered in laboratories in England, using a pair of snapdragon genes as genetic “on switches” that cause the tomatoes to produce purple pigments in the flesh as well as their skin.

Professors Cathie Martin and Jonathan Jones formed a company called Norfolk Plant Sciences to produce and sell seeds.

The company received regulatory approval from the US Department of Agriculture last fall to begin selling the new variety in the US.

In addition to the fruit’s eye-catching appearance, the company says the purple tomato has a longer shelf life and improved nutrition, particularly the antioxidant anthocyanin, which has anti-inflammatory properties and may reduce the risk of cancer and heart problems.

Seeds could be available later this year.