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Welcome to ‘perennials month'

The phrase "June is perennials month" was probably designed to sell plants, but it also is true. June is the perfect time to create, improve or tend your perennial garden. There are a number of reasons:

* Gardening weather in the Northeast is perfect: many sunny but comfortable days, cool nights, periodic rainfall (we hope), and the soil is warm.

* We have had time to prepare our gardens: cleaning up debris, cutting back dead tops, edging beds, adding compost, refreshing mulch.

* Plants have shown up – dead or alive – including those that reveal themselves late: Asclepias (butterfly weed), Platycodon (balloon flower), hardy hibiscus and Buddleia (butterfly bush). We know where the holes are.

* Most plants are still small enough to transplant or divide. Some qualifiers here: If plants are already tall – Chelone (turtlehead) or Baptisia – or flowering now or soon – Campanulas or roses – wait awhile. You could cut most of those back (say, to half their heights) after they have flowered and then move or divide them, or you could wait until September or next spring.

* Garden centers and nurseries are full of perennials. Caveat: Don't just fall in love with the plants you see flowering, or you will have a garden full of mostly spring and early summer flowers. Ferret out the late summer and fall bloomers, that are mostly small green plants at the moment.

* You are still in the gardening mood. Everybody's a gardener on the first warm days of May and June. But capture the momentum and keep going: thinning, dividing, thorough weeding, amending soil and watering deeply.

* Containers and window boxes may be full, but great annual flowers will continue to be available to fill in the garden or decorate the deck for some weeks.

* June perennial gardening sets the stage for the coming garden tours and walks. Between late June to August, nearly 1,000 gardeners are officially on a weekend walking or bus tour, or offer an "Open Garden" for Thursday or Friday visitors, as part of the National Garden Festival (nationalgar? Many other gardeners are getting ready for parties and guests in their own backyards.

> Some hard choices

At some point most gardeners run out of space (or time or strength) and have to choose among old favorites and new beauties. Sad as it may be to do, I strongly recommend replacing unimpressive plants with better performers. A perennial should either provide an extended period of bloom, truly extraordinary (wow-inducing) flowers or have other attractive features throughout the season – fine form or structure, great foliage, berries or fall color. If not, look further.

Decades of intense hybridizing and plant discovery have provided us with perennials that our ancestors could not have imagined. As much as we romanticize old-time gardens, the reality is that the picture-perfect gardens of yesteryear were tended daily by the gardener or garden staff; it wasn't generally about amazing plants.

Which perennials are most improved? I asked this of expert Susan Martin, director of marketing communications for Walters Gardens of Zeeland, Mich. (the largest wholesale perennials grower in the United States). Her answer: "Most improved perennial: Daylilies. Decades of breeding work have brought us vastly improved cultivars that are much longer blooming, have higher bud counts, superior quality flowers that keep their color all day, and foliage that remains attractive all season long. The difference between older daylilies and the new modern hybrids when compared side by side is astounding."

Among her favorites: ‘Going Bananas' and ‘Ruby Spider.' Watch also for other rebloomers such as the lovely, white ‘Sunday Gloves.'

Other genera and species also keep getting better – from salvias to coneflowers, from coral bells to perennial geraniums – and we all have our pets. I go through phases, now favoring Monarda ‘Petite Delight' because it's so compact, or Penstemon ‘Dark Towers' for its maroon foliage, or ‘Gold Heart' Dicentra because it stays gold all summer. But then, there also are the red-flowering bleeding heart ‘Valentine' and ‘Iron Butterfly' (a short New York ironweed cultivar).

This season some newer perennials have impressed me:

* Rudbeckia ‘Little Goldstar,' a more compact and refined version of the workhorse black-eyed Susan ‘Goldsturm.'

* Coreopsis ‘Galaxy' and ‘Redshift' – both brighter, sturdier, covered with buds and preparing to bloom all season.

* Leucanthemum ‘Banana Cream' as well as other great shasta daisies such as ‘Sante' and ‘Sunny Side Up.'

* Melittis (Bastards Balm), a little known, short perennial that's covered with orchidlike small flowers right now.

* Echinacea ‘Green Jewel' – or any number of them in sunset colors that have left purpurea waybehind.

As you weed, thin, water and dig in your perennial gardens, think about which sections and which plants truly perform, and where a new choice could be the answer. I suspect a few improved plants could sustain your garden through some summer doldrums, and there's a whole industry full of growers, hybridizers, designers and experts ready to make that happen.

Enjoy June. It's Perennials Month!

Sally Cunningham is a garden writer, lecturer and consultant.