Clematis Pruning 101

Mar 07, 2016

Some gardeners may make pruning mistakes in their haste to tidy up their gardens in the spring, according to a University of Illinois Extension horticulture educator.

“The old adage is ‘you prune when your pruners are sharp’,” says Sandy Mason. “Many plants can be pruned in the spring. But wait, take a deep breath, and step away from the shears. If flowers are the goal, take a moment to determine how the plant grows.”

The primary factor is whether the plant produces flowers on old wood (last year’s stems) or new wood (this season’s new stems). Mason explains, “As a general rule, plants that bloom before June 15 bloom on old wood and plants that bloom after June 15 bloom on new wood.”

For plants that bloom on old wood, it is best to prune right after they flower. For other plants, as a general rule, it is best to wait and do severe pruning in spring just before the plant’s active growth.

“Incorrectly pruned plants usually don’t die from pruning mistakes,” Mason reassures. “Worst case scenario, flowers are delayed until later in the season or until next year.”

Some plants are more foolproof, such as ‘Endless Summer’ hydrangeas and reblooming roses. They bloom on new and old wood; therefore, they should flower no matter when they are pruned.

Determining when to prune clematis plants can be a little more difficult, due to the many different types of clematis. Confusion also arises in early spring because all the stems appear to be dead.

“If you are new to pruning clematis, wait a couple weeks and prune when the buds start to show green growth, so you can tell the dead from the living,” Mason suggests.

Clematis cultivars are placed in groups according to pruning needs and flowering periods. Designations vary depending on the author. Groups include: A, B, C, or 1, 2, 3, or little pruning, half pruning, or hard pruning.

Group 1 or A is composed of the early flowering species that bloom from late April to late May and require little pruning. These flower on old wood. In spring, only the dead stems need to be removed.

Group 1 includes Clematis alpina ‘Constance’ and ‘Pamela Jackman’; Clematis macropetala ‘Lagoon’; and Clematis montana ‘Elizabeth’.

Group 2 or B clematis are early, double and, semi-double mid-season cultivars. They bloom in mid- to late May and, if healthy, will bloom again in September through October. These flower on both old and new wood. Prune lightly in spring when buds begin to swell, removing dead and weak stems and reducing size, if needed. The largest flowers will be produced on the old wood, while new growth will provide blooms for the late season. Group 2 can be pruned again immediately after flowering, if needed.

Group 2 includes hybrid cultivars ‘The President’; ‘Vino’; ‘Anne-Louise’; ‘Arctic Queen’; ‘Bees Jubilee’; ‘Crystal Fountain’; and ‘Rosemoor’.

Group 3 or C clematis are the late large-flowered cultivars and other late blooming clematis species. These vigorous vines are easy to prune and require a hard annual prune. They bloom on new wood, so it’s hard to go wrong. Cut to a pair of healthy strong buds at the base of the plant in spring as the buds swell. If unpruned, flowers are produced at the top of an unattractive and leggy plant.

Group 3 includes hybrids ‘Comtesse de Bouchaud’, ‘Rouge Cardinal’, ‘Duchess of Albany’; C. tangutica; C. viticella cultivars such as ‘Etoile Violette’, ‘Polish Spirit’, and ‘Madame Julia Correvon’; and some of the non-vining clematis, such as Clematis durandii and Clematis integrifolia. The sweet smelling, late blooming hybrid ‘Sweet Autumn’ is also in this group.

According to Mason, it is worth taking the time to do the homework on clematis to make the most of these attractive plants.

Source:illinois.edu

Video: Why Your Food Future Could be Trapped in a Seed Morgue

In a world of PowerPoint overload, Rex Bernardo stands out. No bullet points. No charts. No jargon. Just stories and photographs. At this year’s National Association for Plant Breeding conference on the Big Island of Hawaii, he stood before a room of peers — all experts in the science of seeds — and did something radical: he showed them images. He told them stories. And he asked them to remember not what they saw, but how they felt.

Bernardo, recipient of the 2025 Lifetime Achievement Award, has spent his career searching for the genetic treasures tucked inside what plant breeders call exotic germplasm — ancient, often wild genetic lines that hold secrets to resilience, taste, and traits we've forgotten to value.

But Bernardo didn’t always think this way.

“I worked in private industry for nearly a decade,” he recalls. “I remember one breeder saying, ‘We’re making new hybrids, but they’re basically the same genetics.’ That stuck with me. Where is the new diversity going to come from?”

For Bernardo, part of the answer lies in the world’s gene banks — vast vaults of seed samples collected from every corner of the globe. Yet, he says, many of these vaults have quietly become “seed morgues.” “Something goes in, but it never comes out,” he explains. “We need to start treating these collections like living investments, not museums of dead potential.”

That potential — and the barriers to unlocking it — are deeply personal for Bernardo. He’s wrestled with international policies that prevent access to valuable lines (like North Korean corn) and with the slow, painstaking science of transferring useful traits from wild relatives into elite lines that farmers can actually grow. Sometimes it works. Sometimes it doesn’t. But he’s convinced that success starts not in the lab, but in the way we communicate.

“The fact sheet model isn’t cutting it anymore,” he says. “We hand out a paper about a new variety and think that’s enough. But stories? Plants you can see and touch? That’s what stays with people.”

Bernardo practices what he preaches. At the University of Minnesota, he helped launch a student-led breeding program that’s working to adapt leafy African vegetables for the Twin Cities’ African diaspora. The goal? Culturally relevant crops that mature in Minnesota’s shorter growing season — and can be regrown year after year.

“That’s real impact,” he says. “Helping people grow food that’s meaningful to them, not just what's commercially viable.”

He’s also brewed plant breeding into something more relatable — literally. Coffee and beer have become unexpected tools in his mission to make science accessible. His undergraduate course on coffee, for instance, connects the dots between genetics, geography, and culture. “Everyone drinks coffee,” he says. “It’s a conversation starter. It’s a gateway into plant science.”