Monthly Archives: August 2022

Design trends

Hardy Geraniums in the Garden

Hardy geraniums are easy to care for and make lovely ground covers.

Last fall my neighbor planted the slope in front of their house with hardy geraniums- lots of them. Over the winter they were looking a bit scraggly and I was worried that maybe they had chosen the wrong ground cover for their situation. But no, come last spring their rich blue geranium ‘Rozanne’ burst into bloom and it’s a site to behold.

Most people use the common name geranium to describe what is actually a pelargonium. Ivy geraniums, Martha Washington pelargoniums and zonal geraniums are all pelargoniums. Hardy geraniums, also called cranesbill, look very different. Leaves are roundish or kidney-shaped and usually lobed or deeply cut. Flower colors include beautiful blue, purple, magenta, pink or white and often completely cover the plant with color. I’ll bet if you visited a garden on a tour or admired a picture in a garden magazine it contained true geraniums. Here are just a few strong performers available among the dozens of species.

Geranium maderense grows best in shade. This dramatic native of Madeira is the largest geranium with huge 1-2 foot long leaves shaped like giant snowflakes. Clusters of thousands of rose tinted flowers form on a 3 foot trunk. This perennial is short-lived but self sows freely. Add some of these architectural plants to your border for color and structure.

Blue flowers in the garden are always a hit as they combine so well with other colors. Geranium Orion‘s abundant clear blue flower clusters bloom over a long season. Use this 2 foot spreading plant in sun or part shade in a mixed border or as a groundcover. There are other blue flowering geraniums. I grow geranium ‘Brookside’ on my own garden. It’s on the second round of blooms. It’s large bright blue flowers are larger than ‘Johnson’s Blue’. ‘Rozanne’ is another common favorite with stunning blue flowers.

Looking for a fast growing variety? Geranium incanum which covers itself spring through fall with rosy violet flowers, fits the bill. Cut back every 2-3 years to keep neat. This variety endures heat and drought better than other types but needs some summer water. It self seed profusely which might be exactly what you want for a groundcover in a problem area.

Geranium Biokova

If pale pink is your color, plant geranium x cantabrigiense ’Biokova’. This excellent groundcover spreads slowly. The numerous one inch flowers are long lasting and cover the plant from late spring to early summer. Their soft pink color is indispensable when tying together stronger colors in the border and the lacy foliage is slightly scented.

Another geranium in the same family is ‘Karmina’. I’ve been growing this dark pink flowering variety for several years. With lush green leaves on a low spreading plant it’s pretty even when not in bloom.

There are a couple other varieties that are popular and deserve a try. They are Award Winning ‘Mavis Simpson’ and ‘Russell Pritchard’. Both have bright pink or purple flowers and make good additions to your perennials.

Give the hardy geranium a place in your garden.

Design trends

Planting Under Trees

Be careful when planting under dogwood

Many of us live under oaks or are surrounded by redwoods. We know the value of trees in the landscape. Trees shade us in the summer. We anticipate their showy blossoms in the spring and enjoy their beautiful colorful foliage in the fall. You can hang a hammock between two of them or tie a rope swing for the kids from a large branch. Trees are our companions, but how can you create a garden under one of them?

Planting under a mature tree can be a challenge. You need to avoid damaging their roots and your new plants will need to cope with dry soil, shade, root competition and ever-changing moisture and light conditions. You want both your new plants and your tree to thrive.

Meet your tree’s needs first. Some trees are more agreeable than others about giving up some of their ground. You can still plant beneath trees that are sensitive to having their roots disturbed but you’ll need to make a few concessions. When purchasing plants to grow under trees, think small. Small plants require a smaller planting hole and this will minimize disturbance to the roots. You may have to buy more plants but you’ll have an easier time tucking them among the roots.

Don’t alter the grade of the soil around a tree or change the soil pH very much. Even adding a layer of soil that is more than 2 inches deep can reduce the amount of moisture and oxygen available to the tree and hinder gas exchange to existing roots, causing trees to suffer or even die.

Only the toughest plants have a chance of surviving among the surface roots of shallow rooted trees. Be careful when disturbing sugar maples, elms. cherries and plums, dogwoods, magnolias, pines and oaks. The majority of a tree roots are small woody roots and fine hair roots that grow within the upper 12-18 inches of soil and extend far beyond the trees drip line. These roots are responsible for absorbing water and nutrients from the soil.

If you encounter a root larger than 1 1/2 – 2 inches in diameter while digging a hole for a plant, move the planting hole a few inches away to avoid slicing through the root. You will sever mats of small tree roots when digging, but they’ll regenerate fairly quickly.

To avoid wounding the bark, which may cause insect and disease problems, start planting at least 12 inches away from the trunk. Oaks shouldn’t have any plantings closer than 6-10 feet from the trunk and those should be drought tolerant. After planting, water to settle the soil and spread 2-3 inches of mulch to conserve moisture and keep weeds down. Be sure to keep mulch at least 12 inches away from the base of the tree. Mulch can hold moisture against a tree’s bark and cause rot and disease.

A Forest Pansy redbud in fall color.

Trees that will tolerate some disturbance to the root zone include Eastern redbuds, both the green-leafed and the purple- leafed species, and red maples which are also a good lawn tree. Common trees that are easy going about plantings underneath are crabapple, ginkgo, hawthorn, honey locust, poplar, silver maple and willows.

So what plants will transform your bare patch of hard earth and knobby roots into a shady nook? If you’re going for a lush look, consider hostas and ferns, paired with the hardy geraniums like Biokova. Other good companions are astilbes with their feathery flower plumes and variegated euonymus fortunei with bergenia or digitalis mertonensis with liriope, lamium, vinca minor, hellebore or brunnera.

Trees with branches limbed high look good with small shrubs planted underneath. Red-leaf barberry can brighten up this spot and also provide fall color. Small nandinas like Harbor Dwarf make a good ground cover and their foliage takes on an orange-red color in winter. Fragrant sarcococca grows well in this situation, too.

Low groundcovers make a simple statement under the crown of a tree. Ajuga, pachysandra and sweet woodruff all grow well here. Or you might like the look of the shade tolerant grass-like plant like carex morrowii ‘Evergold’. This stunning sedge makes a beautiful clump 1-2 feet high and 2-3 feet wide with dark green leaves and a central band of creamy white.

You can have a beautiful garden under a mature tree by following these tips.

Design trends

How & When to Espalier Plants

This local star jasmine has been trained in the formal
Belgian Fence style

Over the years I’ve visited many gardens and been asked for advice on how to deal with a narrow space. We all have ‘em. Sometimes it’s that area between the garage and the fence. Or maybe the neighbor’s deck overlooks your patio but there’s not room to plant a hedge. Or maybe you want to break up your garden with a graceful screen that doesn’t take up too much space. Whether you have an edible in mind that would look great in that space or want an ornamental plant to bring some color, flowers, birds & butterflies, there are lots of choices for shrubs to train as an espalier no matter what your growing conditions are.

I’ve read that the practice of espalier originated in Medieval times when residents of warring cities planted trees inside their walled cities. The Roman and Egyptians are also said to have trained fruit bearing plants like fig, apple, pear and citrus in their gardens but it was the Europeans, specifically the French who perfected the designs we see today.

A nicely trained apple.

Dwarf pear and apple trees are pretty easy to train. Both these trees produce thickened spurs which is where the fruit develops so don’t lop them off when you prune. They are easy to see. You’ll need cat least 6 hours of sun a day for them to produce fruit.

Camellia thrive in shade and because they have flexible branches they lend themselves to training. Pyracantha is also forgiving of mistakes for this reason.

Narrow spaces can be challenging. One of my favorite plants that naturally grows flat is grewia occidentals or Lavender Starflower. it grows fast in sun and attracts hummingbirds and other birds. Beautiful lavender flowers cover the plant from spring to fall.

Another plant, azara microphylla, also grows flat without much coaxing on your part. This small dainty tree is fast growing and reaches 15-25 ft tall. The yellow flower clusters will fill your garden with the scent of white chocolate in late winter. They are ideal between structures. I’ve used the variegated version to screen a shower and it’s working great. The chocolate fragrance of this plant is really what makes it a show stopper.

Flowering quince is an old garden staple providing early color. They are easy to care for and nearly indestructible in almost any soil that is well drained and not overly fertile. Once established quince is a very drought tolerant plant and their spiny branches make them an excellent choice for hedges, screening or as a security barrier. There are red, pink, orange and white flowering varieties. The Toyo Nishiki cultivar even has pink, white and solid red flowers all on the same branch.

Another small tree, the Compact Carolina cherry laurel can be espaliered also in a narrow space if needed. It grows 10 ft tall but that may be all you need to screen the neighbor. They are drought tolerant once established, deer resistant and the perfect host for birds, bees and butterflies. The leaves smell like cherries when crushed which gives this plant it’s common name.

Other ornamental shrubs that make great espaliered plants are abutilon, bougainvillea in frost free areas, callistemon, dodonaea, feijoa, gingko, sarcococca, viburnum, ribes, rhaphiolepis, pittosporum tobira and osmanthus fragrans. Trees that can be trained include cercis, agonis flexuosa, eriobotrya, and podocarps.

California native plants that can be espaliered are garrya, fremontodendron. Carolina cherry, flowering currant and ceanothus while the branches are young and supple.

A young fruit tree in training

Don’t be overwhelmed if an espalier gets out of hand during the season. Just nip the branches back to a leaf node. Use heavy jute to attach the branch to the support wire or stake. After a season the jute will rot away which keeps the branch from being girdled by the restraint.