All posts by Katherine Tracey

Pelargonium sidoides

Pelargonium sidoides

This has been one of our favorite species “Geraniums” since we first offered it in 1997. Pelargonium sidoides is native to South Africa, and herbalists may be aware of it’s medicinal qualities for colds and bronchitis. We grow P. sidoides because it is superbly ornamental.

P. sidoides has attractive aromatic silvery gray foliage, and wiry branches with wispy clusters of dark wine colored blossoms, which are continuously produced all season. It does best in full sun, and forms tidy mounds 6-10″ tall with a spread of about 12-15″ in a season. It seems to perform admirably in both cool and hot summers, and, although only winter hardy to 20 degrees F, will easily winter over on a sunny window sill.

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Planting Containers

Focus on foliage

Container Gardening is a summer long activity. Plants grow quickly, and it is only a matter of week or two before a new grouping “knits” together. You can move, mix and match pots all season long.

We’d like to pass on basic tips for successful container plantings.

1. Select plants that all like similar growing conditions (i.e…sun, shade, dry soil, moist soil).

2. Use a good quality potting soil amended with an organic plant food like Garden Tone and/or Osmocote time release fertilizer. 

3. Remember to select/focus on plants with interesting foliage, which will add color and texture without the need of constant flower deadheading. Think of the flowering plant choices as the “accents”.

4. Finally, liquid feed with Dyna Grow or Seaweed/Fish Emulsion on a regular basis, which will replace the nutrients leached out of your pots from frequent watering.

Rhododendron ‘New Century’

‘New Century’ is another tidy compact Rhododendron, with pale citron yellow blossoms. It has a very full foliage appearance due to the fact it holds its evergreen leaves for 3 years, rather than just 2 like most other rhodies. It grows to a well behaved 4′ x 4′ size and is quite hardy for a yellow form, (to minus 15F).

Grow this selection in a spot protected from drying winter winds. Morning suns and afternoon shade is ideal, but plants can take more sun if well irrigated during drier conditions. Like all Rhododendrons, ‘New Century’ appreciates a humus rich soil that remains moist but well drained. 

Rhododendron ‘Blue Baron’

Handsome violet blue blossoms in late April/early May distinguish this welcome addition to the mid spring garden. Introduced by Weston Nursery of Hopkinton MA, Rhododendron ‘Blue Baron’ falls into the lepidote group of Rhodies, which with a few exceptions, have smaller leaves, smaller more open trusses and prefer to grow in a more sunny spot. ‘Blue Baron’ has a compact habit,and is often listed as growing to 3-4′ in height and width, but at maturity can reach 6?. His fine textured elliptical foliage is glossy green in summer but takes on a bronzy cast in colder months.

Grow ‘Blue Baron’ in humus rich soil in full or part sun, and morning sun with some afternoon shade has proven ideal . He can tolerate a bit of wind, but we recommend using an anti-dessicant if winter winds are harsh. Like all Rhododendrons, ‘Blue Baron’ is shallow rooted, and will need irrigating during dry spells. Hardy to minus 10F.

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The Right Time to Plant Tender…

Here in the northeast, mid spring teases us with periods of warm sunny days, tempting us to go out and buy the colorful annuals and tropical perennials stocked in local greenhouses. We forget that we may well get several more chilly nights. Perhaps frost is unlikely, but the soil temperature is going to remain too cold for the heat lovers until nights stay above 55 degrees F. If you plant these warm weather gems too soon, you will most assuredly stunt their growth.

The old timers always said to wait until Memorial Day to plant tomatoes and annuals, and for good reason. Only last year, many of us experienced a cool wet June, and many a northern gardener lamented how poorly Coleus, Colocasia and Cannas performed.

Phlox divaricata ‘Blue Moon’

The best selection of Woodland Phlox, in our opinion, is this lovely cultivar introduced by Bill Cullina, of Coastal Maine Botanical Garden. Abundant deep sky blue flowers on 12″ stems perfume the May garden, and when planted en masse create ethereal drifts. It makes an excellent companion for woodland poppies and late blooming narcissus

‘Blue Moon’ grows best in light shade in a rich humusy soil that is moist yet well drained, forming clumps 2-3′ across. After the blossoms fade, cut back the spent flowering stems for a neater appearance. It is hardy in zone 4-8.

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Hydrangea macrophylla ‘Red Sensation’

Gardeners in northern climates have been disappointed  by Hydrangea macrophylla in the past….lots of healthy foliage, but few or no blossoms. This recent introduction of Mophead Hydrangea truly blooms on both old and new wood,  and is being marketed as ‘Forever and Ever Red Sensation’ ( Tra-la-la…those clever marketers read a lot of fairy tales).

What you really need to know is that this vigorous selection produces lots of blooms on new growth, making it a great candidate for colder zone 5 and 6 gardens. In hot climates the large trusses of blossoms will be in softer shades of rosy pink when grown in neutral to slightly alkaline soil. Colder temperatures will cause the flower color to deeper red shades. If your garden soil happens to be more acidic, ‘Red Sensation’ will change color and thus need a new name, as it will take on bluer tones. The flowers age to smoky violet. Stems and fall foliage color have a dark burgundy cast.

Red Sensation’ grow 2-3′ tall and 3-4’wide, and require full sun or partial shade. Hydrangea macrophylla appreciate a moist, rich and fertile soil.  May we suggest combining ‘Red Sensation’ with the always attractive Periscaria ‘Golden Arrow’? 

Pruning Hydrangea

Hydrangea paniculata ‘Limelight’ blooms on new growth

Even seasoned gardeners seem to be confused as to when to prune Hydrangea.

Begin by identifying which Hydrangea species you are growing, to determine whether it will bloom on new growth or on old wood (last year’s stalks). The species arborescens, paniculata and some newer forms of macrophylla bloom on new wood. All the Hydrangea macrophylla (Mophead and Lacecap types) and quercifolia (Oakleaf)  bloom on old wood, as long as there isn’t winter damage. Next year?s blossoms are set on the upper portion of the woody stalks in late summer and fall. H. macrophylla selections should not be pruned until after the plants have leafed out. In late spring, prune out or tip back any dead wood for a clean appearance.

The hardiest and most foolproof of all the Hydrangea are the paniculata group (Pee Gee types) and the arborescens group (Smooth Hydrangea). Both of these species can be cut within inches of the ground each spring if you want to control the size of your plants.  They stalks can always be thinned to improve plant shape, and there is no harm to next year’s display if you want to cut long stemmed bouquets in summer and fall.

There are a lot of new Hydrangea macrophylla selections on the market, including ‘Double Expressions’, ‘Red Sensation’, ‘Let’s Dance Starlight’, and ‘Endless Summer’ that bloom on old and new wood. The blossoms appearing on old growth will display in early summer, while the flowers that form on new growth will appear later in August and September, for a long continuous display. If you live in the colder parts of zone 6 or zone 5, you may get too much winterkill for blossoms on the old growth, but you will still be able to enjoy a late summer through fall display.

Meehania cordata

What has spring time blue flowers, grows 4-6″ tall, spreads by creeping runners, thrives in partial shade or shade in moist or drier soil? Meehania cordata, commonly known as Meehan’s Mint! This versatile and underused Northeast native is a good substitute groundcover for Lamium and Ajuga. It blooms in May and June with violet blue lipped tubular blossoms and would make a lovely underplanting for golden leaved Hosta and Hakonechloa (Japanese Forest Grass).

Although it is especially vigorous in moist soil, and would be a good choice for carpeting along a pond or stream, it will also grow well but more slowly in drier spots. It is hardy in zones 5-8 and would be a welcomed addition to a wildflower garden.

Making Your Bed for Spring III

Should you lime your garden?

Here in the northeast, we seldom consider the effects of acid rain anymore.  Since most public water departments deliver water with a neutral ph, the effects of acid rain have been largely neutralized in landscapes that use public water.  Still, we cant be certain of the soil pH unless we periodically test it. it is a good idea to purchase soil pH testers, either online or at a local garden centers.