Container Gardening

This simple arrangement features red fountain grass as the
thriller with a sedum spiller.

When I moved up here to Bonny Soon from Felton I brought several hundred plants figuring that with over 2 acres of land I could put most of them in the ground. Many trees and shrubs did get planted but then I ran out of appropriate planting spots and just kept the rest in pots to create a container garden. Naturally, I’ve added more plants in pots ‘cause I just can’t help myself when I see a colorful plant that will attract birds, bees and butterflies. My current count of potted plants is 253 so I’ve learned a thing or two about container gardening.

This container grouping for shade has just one type of plants per pot.

Mixed plantings in containers are the most dramatic with a thriller, some fillers and and a spiller or two but when I look around that’s not what I have the most of. Many of my large pots have trees like Dawn redwood, Japanese maples, flowering plums and cherries that I’ve had since the early ’90’s so I might underplant them with chartreuse sedum ‘Angelina’ or moneywort for a little color but that’s about it. I’ve found that even large trees and shrubs can survive in the same container for many, many years without root pruning or transplanting if they are fertilized once a year and watered thoroughly as needed.

In choosing a container, remember a porous clay pot will dry out fast in the summer sun as will a small pot. If you want pots on a sunny deck, you’ll have better results if your container is made or ceramic or colored plastic and is big enough to allow 2 inches of potting soil around the root ball. I don’t use water absorbing polymer granules in my containers as they are all in shade in winter and would stay too wet depriving plant roots of oxygen.

Water when the top 1 inch of soil in the container is dry. On a very hot day, watering mid day will cool the soil although I like to get my watering done early. Get to know your plants. Plants that are still growing into their containers need less frequent watering than those that are getting root bound. How much water? Water until it runs out the bottom and empty the saucer the next day if any water remains. Use a gentle nozzle that doesn’t dislodge the soil or compact it. Also make sure the water in the hose isn’t hot from lying in the sun.

Plants in containers are watered frequently and the water draining out of the bottom carries away nutrients. That said I have found that I can fertilize everything once a year with an organic all-purpose fertilizer like True 4-4-2. Blooming plants like abutilon, fuchsia, orchids, angel trumpet and the lantana, which I grow because the chipmunks don’t nibble them, receive a water soluble fertilizer once a month. Water soluble fertilizers are fast acting. Dry granules and time release capsules last longer. Organic fertilizers tend to work more slowly and are especially ideal for trees, shrubs and long lived perennials or for large planters in which you keep the same soil from year to year. Be sure plants are moist before feeding. The best fertilizer is the one that you get out of the package and onto your plants.

A group of succulents and cactus at Succulent Gardens in Castroville.

Be sure to use a quality potting mix in your containers. There are special succulent and cactus mixes available but succulents are forgiving as long as the soil drains freely. Don’t add gravel or clay shards at the bottom of the pot as this impedes drainage. It work best to fill the entire pot with soil, top to bottom with a screen over the hole to keep out earwigs and sowbugs.

You can grow anything in a container. Think of them as furnishings. Grow herbs and other edibles near the kitchen door, fragrant flowers to attract beneficial insects, hummingbirds and butterflies, California natives or even plants that glow in the moonlight.

Fragrance in the Garden

This dwarf butterfly bush called Buzz Hot Raspberry attracts butterflies and smells delicious.

Last year I bought a dwarf butterfly bush and planted it in a pot near my entry. I’m not sure if it’s a Buzz Hot Raspberry or a Lo & Behold Pink Microchip but it’s in full bloom and will continue through fall if I keep it deadheaded. The swallowtail butterflies love it and the scent is so sweet and so strong I can smell it through an open window. In this time of hanging out more at the homestead it brings a smile to my face.

Fragrance in flowers is nature’s ways of encouraging pollination. Just as it draws you to take a deeper whiff, it lures insects to blossoms hidden by leaves. Some flowers are fragrant only at night and attract night-flying pollinators like moths, while others are more fragrant during the day and attract insects like bees and butterflies. The fragrance itself comes from essential oils called attars that vaporize easily and infuse the air with their scents.

Aroma chemistry is complex and the smell of any flower comes from more than a single chemical compound. These molecules are present in different combinations in different plants, but often they are markedly similar which is why there are irises that smell like grapes and roses that smell like licorice. Our noses can detect those chemical compounds that have a major impact on the aroma. Often a particular molecule will make a large contribution.

Some roses, for instance, derive their scent from rose oxide and others from beta-damascenome or rose ketones. These molecules are detectable by our noses at very, very low concentrations. Carnations, violets, lilies, chrysanthemums, hyacinth- all have their own set of compounds that contribute to their scent.

It’s interesting also that as we become accustomed to the same smell our brain phases it out. A compound called ionones, found in violets and rose oil, can essentially short-circuit our sense of smell, binding to the receptors. This shut down is only temporary and the ionones can soon be detected again and registered as a new smell.

Place sweet-smelling plants where you can enjoy them throughout the season. The potency of flower scents varies greatly, so consider the strength of a fragrance when deciding where to put a plant. Subtle fragrances such as sweet pea. lemon verbena, scented geranium and chocolate cosmos smell wonderful right outside the back door. Add stronger scents by your deck, pool, spa, dining area or gazebo. Stargazer lilies, jasmine, lilacs, daphne, citrus and peonies will make you want to stay awhile.

Several easy-to-grow shrubs have fragrant flowers as an added bonus. Mexican Orange (choisya ternata) blooms most of the year. Pittosporum eugenoides, tenuifolium and tobira all have tiny blossoms that smell like oranges. too. The tiny flower cluster of Fragrant Olive (osmanthus fragrans) have a delicate apricot fragrance.

Other fragrant plants include California native Philadelphus lewisii (Wild Mock Orange). Calycanthus occidentals (Spice Bush) is native to our Central and Northern California mountains. Their fragrant burgundy flowers smell like red wine. Ribes viburnifolium, carpenteria californica and rosa californica are mildly scented, too.

In spring there may be nothing quite as spectacular as a wisteria vine, loaded with fragrant purple, pink, blue or white flower clusters, covering an arbor or pergola. Pink jasmine is another vigorous vine with intensely fragrant flowers as is Evergreen Clematis.

I can’t leave out the old fashion border carnation or dianthus. Their clove-scented flowers are born in profusion making them a nice addition to the mixed flower border and containers.

The list goes on and includes scented plants such as nemesia, wallflower, Japanese snowbell, hosta, coneflower, vitex, viburnum, nicotiana, phlox, rose, sweet pea, hyacinth, lilac, flowering crabapple, heliotrope, lavender, sweet alyssum, peony, moon flower, southern magnolia.

Angel’s Trumpet grow well in containers. Their dramatic, fragrant flowers scent the evening air.

Be sure to include fragrant plants that release their scent in the evening, especially in the areas of the garden you most frequent after dark. Since the majority of night-scented blossoms have white flowers, these plants also light up the landscape at night. Angel’s Trumpet (brugmansia) is one such plant as is flowering tobacco and night blooming jessamine.

Plant vines for fragrance in your garden. Evergreen clematis (clematis armandii) bloom with showy white fragrant flowers clusters above dark green leaves in the spring. Clematis montana is another variety of clematis that’s covered with vanilla-scented pink flowers in spring also. Carolina jessamine’s fragrant yellow flower clusters appear in masses from late winter into spring.

Ideally, when you’ve finished, your garden will smell as intriguing as an expensive perfume. The top note will be floral- jasmine, honeysuckle, rose. The middle register will be spicy, such as the vanilla of heliotrope or purple petunias or the clove of dianthus. Finally underneath, the tones that give perfumes their vigor, like artemisia, sage and santolina.

Not every inch of the garden needs to be fragrant but a waft or two of fragrance from the right plants can turn a garden from ordinary to enchanting.

Watering 101

This combination of Safari Sunset leacadendron, Guardsman phormium and succulents has low water needs.

Is your garden starting to look a little bedraggled? After a few hot spells, have the plants in your yard gotten a taste of what’s to come for the rest of the summer? After you’ve chosen climate adapted plants how much water do they really need? Here’s how can you keep everything happy and not waste water.

All plants need water- even those that are tolerant of our summer dry conditions. Water makes up 90-98% of every plant we grow. It’s needed for photosynthesis, as well as reproduction and defense against pests.

With summer water bills arriving this is a good time to re-visit how often and how much to water that landscape you’ve spent so much money to create. Basically, you’re wasting water if you’re not watering deep enough to moisten the entire root ball or if you’re irrigating too often.

Photosynthesis is one of the most remarkable biochemical processes on earth and allows plants to use sunlight to make food from water and carbon dioxide. At temperatures about 104 degrees, however, the enzymes that carry out photosynthesis lose their shape and functionality. A garden that provides optimum light and water but gets too hot will be less vigorous.

Plants have natural systems that respond to heat problems. Plants can cool themselves by pumping water out through the leaves for a kind of swamp cooler effect. They can also make “heat-shock” proteins which reduces problems from over heating. All these strategies can take resources away from a plant’s other needs like growth, flowering and fruiting.

So how much water do different types of plants need during the heat of summer?

Be sure that you water trees and shrubs deeply, checking soil moisture first with a trowel. Established small to medium shrubs should be watered when the top 3-6 inches of soil is dry. Water large shrubs and trees when the top 6-12 inches is dry.

As a rule of thumb, trees and large shrubs need deep but infrequent irrigation. They should be on a separate valve than your smaller shrubs and perennials. Water ornamental trees 1-3 times per month depending on the type and soil. Tree roots grow 24-36 inches deep or more and require 10 gallons of water per inch of trunk diameter.

California native mimulus auritanicus

Apply water with a soaker hose, drip system emitters or hand held hose with shut off and soft spray attachment according to your water district’s restrictions. Don’t dig holes in the ground in an effort to water deeply. This dries out roots even more. Be sure to water the root zone to the indicated root depth every time you water. Watering deeper than the root zone only means you are wasting water. You can test how deep you watered by pushing a thin, smooth rod into the ground soon after you irrigate. The soil probe should easily slide through the wet soil but become difficult to push when reaching dry soil.

The roots of smaller shrubs reach 12-24 inches deep in the soil. Established native shrubs may need only monthly watering to keep them looking their best while other shrubs may need watering every 7-10 days during the heat of the summer. Perennial roots only go down 12 inches or so and may need watering once or twice a week depending on type.

When is the best time to water? Watering in the morning is the most efficient whether you water by sprinkler, drip system, soaker hose or by hand because the water soaks deep in the soil without risk of evaporation. This bolsters the plant for the day and has dried from leaves by evening reducing the risk for foliar diseases like mildew. Plant roots are also more receptive to watering in the morning.

Is it true that water droplets will scorch leaves in the midday sun? According to a study, fuzzy-leaved plants hold water droplets above the leaf surface and act as a magnifying glass to the light beaming through them so there is a very slight chance of scorch.The study also reported that water droplets on smooth leaves, such as maples, cannot cause leaf burn, regardless of the time of day. But no matter the time of day, a plant that needs water should get the right amount.

Knee High by the Fourth of July

A black-tailed deer celebrating the Fourth of July.

Who doesn’t love corn on the cob fresh either from the garden or farmer’s market? But this column isn’t about growing corn or about patriotic deer, it’s about climate smart plants that hold up to the heat. So let’s get started.

All this talk about “drought tolerant” plants or “water smart” plants is misleading in some ways. What really matters for the success of a plant in your garden is that they are climate smart. You can call the new California garden climate tolerant or climate adapted but it all comes down to the same thing. The plants you choose to grow in your garden should be able to naturally tolerate periods of lower than average water. This doesn’t mean no water during extremely long dry periods. No plant can live without water.

I have two books that I look to for plant ideas when called upon to design a garden in our area. This first was published by East Bay MUD in 2004 and is called ‘Plants and Landscapes for Summer-Dry Climates’. The other book I refer to regularly for ideas and information is ‘California Native Plants for the Garden’. Both are invaluable in these times of water conservation. One of the best tips each of them offer is to garden where you live.

All of us live in a summer-dry climate. Summer-dry gardens are naturally dry for long periods. Knowing which type of plant community you live in can make the difference between success and failure in your garden. Choose the right plant for the right place whether it’s a California native from an area with similar soil and exposure or a plant from another Mediterranean-like climate with growing conditions like yours.

Plant communities have evolved over time with geologic changes in climate, topography and soils. We have several district areas here- mixed evergreen forest, redwood forest, chaparral and sandhills.

If you live in a mixed evergreen forest you garden with trees like coast live oak, tan oak, madrone, bay and buckeye. Understory plants include ceanothus, coffeeberry, hazel and poison oak. Your soil contains serpentine and granite. Many other unthirsty plants like salvias, lavender, santolina, society garlic, giant feather grass, rosemary and rockrose do well here. California natives such as western mock orange (philadelphus lewisii), wild ginger and western sword ferns grow here also.

Mixed evergreen forest may also be found along canyon bottoms near streams where big leaf maple, white alder, cottonwood, and western sycamore trees grow. Most plant here grow lush in this deep soil. If you are looking to add something new to your garden here consider giant chain fern, aquilegia, dicentra, Pacific Coast iris and fuchsia-flowering gooseberry.

Found in the sandhills, silverleaf manzanita is perfectly suited to its environment.

Chaparral areas are the hottest, driest slopes of these mountains. Dense thickets of manzanita, coyote brush, chamise, coffeeberry, ceanothus, monkey flower and sage are native here. These plants are adapted to little water and often have tiny, thick, waxy, light green or grayish leaves. Soils tend to be rocky and shallow with overlaying rock or a subsoil that is mostly clay. Plants here need to have an extensive root system that reaches widely and deeply for water. If you live here a classic combination would be the spring blooming western redbud and Julia Phelps or Dark Star ceanothus. The combination of magenta and electric blue flowers is unforgettable.

The sandhills near Quail Hollow and Bonny Doon around Martin Rd. are part of an ancient sandy sea floor that was uplifted, eroded and exposed. These sandy soils lack organic matter and nutrients and their white color magnifies the temperature of the summer sun. Unique, native plants like silverleaf manzanita and Ben Lomond wallflower live here. Buckwheat and sticky monkey flower do well here. You might also try growing Lewisia, a pretty little plant native to northern California, thrives in sand and gravel soils with good drainage. This 8″ tall hardy perennial blooms from spring to early summer with extremely showy flower clusters in colors ranging from apricot to pink, rose and bright cherry red. Mulch them with gravel or crushed stone.

Remember right plant-right place. Don’t try to force nature although most gardens do look better with some summer water. Closer to the house we expect a fuller look. Combinations I’m going to try this season include leucospermum paired with blue echium or grey-leafed westringia planted with red-flowering callistemon ‘Little John’.