Herbs in Pots: A Practical Guide to Container Gardening Indoors and Out

Chapter One

Almost anything that will hold soil can, and probably has, been used as a container for herbs—teacups, old shoes, tractor tires—but this is not to say that anything that can hold soil should be used. Personality and experience are critical factors in choosing containers for herbs. For outdoor containers, all but the most fastidious, experienced herb growers should begin with at least a 12-inch-diameter container for most plants, with the possible exception of succulents and other dryland specimens. Small containers may require watering more than once a day or an irrigation system, but we'll get to that later.

    Containers are made of many materials, and each type has its advantages and drawbacks. A gardener takes a clay pot for granted—a simple object, molded from sticky red earth and fired to brittle hardness. Yet a dusty, bone-dry new pot is just the ticket to a new gardening adventure.

    We own more clay pots than most gardeners do—about 600 at last count—because we're nuts about container gardening. There's almost no limit to what we can grow on our patio during the summer. The workhorse of containers is terra-cotta. These pots range in size from smaller than a teacup to more than 3 feet in diameter. They vary from the common, rimmed utility pot to ornately decorated ones. Terra-cotta is available as shallow bulb pots, deeper lemon pots, tall, thin rose pots, and a tremendous variety of fanciful shapes. Gardeners, especially novices, generally get good results when using clay pots for patio containers. By varying the size and adding or removingsaucers beneath the pots, you can find terra-cotta containers for every herb you'd ever care to grow.

    Clay pots have several advantages: terra-cotta "breathes," allowing air to reach the plants' roots. Evaporating moisture from the pot surface cools the roots, much as if they were planted in the ground.

    Terra-cotta's ability to breathe, however, can be one of its biggest drawbacks. Untreated, the dry red clay wicks water from the soil inside the container, drying the plant's roots. So before planting in terra-cotta containers, soak them in water. Small pots are easily submerged in a sink or a garbage can full of water, but larger containers often require a little more imagination. When the container is completely submerged, you'll see strings of tiny bubbles, much like those in a glass of champagne, rising to the surface. When the bubbles stop, the container is saturated.

    Soaking pots can be a bit of a nuisance, but it is well worth the effort. Terra-cotta is so good at wicking water that on hot, dry days it is nearly impossible to pour on enough water to keep the soil moist if the pot itself hasn't been saturated.

    At the end of the growing season, terracotta pots should be emptied and allowed to dry out. Even when they seem dry, enough moisture may remain to make the pots susceptible to cracking or flaking in freezing weather. We lose several pots each winter—we don't have the storage space to bring them all indoors—but we accept this as part of gardening. Each spring before the new planting, it's a good idea to scrub clay pots and to give them another thorough soaking but, seriously, who has the time?

    We're sticklers about watering, but sometimes we miss a pot or two. Pots that have been neglected for a few days during midsummer often will dry out completely, bringing their inhabitants near death. To bring the plants back to life, plunge the pot in a bucket of water to soak the soil and saturate the terra-cotta. Overly dry soil won't absorb water, so returning to the normal watering routine just won't work; the water runs right out the bottom of the pot.

    Glazed terra-cotta and ceramic containers are also available in many sizes, shapes, and colors, and for reasonable prices. These richly toned pots add color to container groupings and work well for many plants, although they don't breathe as do unglazed pots. Their nonporous nature, however, makes them ideal as smaller containers and for moisture-loving plants such as primroses or cannas. Those without drainage holes are ideal as cache pots or for water gardening with horsetails, water lilies, watercress, sweet flag, or water mint (Mentha aquatica). Glazed containers are seldom frost-proof.

    Wooden containers offer many of the advantages of terra-cotta. They are generally lightweight and easily constructed to suit special needs. The biggest drawback to wooden containers is that rot eventually sets in; they don't last as long as containers made from other materials. Some people sidestep this problem by setting pots inside their wooden containers.

    The classic oak half-barrels and some teak containers will last for long periods without preservatives. Because of the ready availability of oak half-barrels, they are great containers for confining invasive plants like mint, artemisias, and lemon balm over many seasons, but more on that later as well. In general, however, oak and teak are quite expensive, although the half-barrels are usually available at a reasonable price. Pine, the most common wood for containers because of its low price, is also the quickest to rot. Several nontoxic wood preservatives may be used to greatly extend the life of wooden containers; check with your hardware store or garden center for a good selection. Avoid creosote and other preservatives that are toxic to plants.

    Plastic containers have some uses—for instance, growing bog plants that have adapted to growing in oxygen-poor soil. Take special care when using black plastic containers that you do not end up making small solar cookers that will parboil the plants they contain. Plants kept in black plastic pots can often be tucked in the back of a grouping of plants to hide the container while shading it from the direct sun.

    Metal containers also suit many herb-gardening uses. Metal containers can be made of steel, iron, brass, lead, or copper, and many are found objects. Steel containers may range from tea tins and milk cans to window boxes made specifically for plants. A coating of rustproof paint will help to extend the life of steel containers, and any metal container used for planting should have drainage holes.

    Cast-iron pots and urns were once rather scarce but have again become fashionable and widely available. Cast-iron containers are extremely durable although they are heavy and difficult to move; nowadays the traditionally shaped urns are reproduced in lightweight aluminum.

    Antique cast-iron urns were often painted to prevent rust, and new containers may be painted to achieve the same look. Because unpainted containers may leave rust stains, situate them where this won't be a problem or seal them with paint or a clear plastic sealant before they are used.

    Antique lead planters, which often began life as cisterns to hold rainwater, are almost prohibitively expensive. Reproductions, generally of lightweight fiberglass, are sometimes found at specialty shops.

    Fiberglass containers, available in a variety of sizes and shapes, generally mimic the shapes and sizes of their lead, stone, terra-cotta, or wooden counterparts. Lightweight and durable, these containers are usually designed to withstand freezing temperatures, making them ideal for year-round use. Many, however, are quite expensive and may turn out to be a costly alternative to replacing less expensive containers occasionally. Like plastic and metal containers, fiberglass pots don't breathe and can heat up in direct sun.

    Wire and plastic are frequently used to fashion hanging baskets. Plastic is lightweight, inexpensive, and holds moisture well but often looks more than slightly unattractive unless completely overgrown with plants. Wire containers make much more attractive hanging baskets, but in climates with low humidity, they dry out very quickly unless lined with a plastic container camouflaged with moss. Plastic liners for wire hanging baskets are available commercially or can be made from a piece of heavy plastic sheeting, but be sure to make at least three or four 1-inch-long slits in the liner for drainage.

    Stone may be shaped to make some of most beautiful and most expensive containers of all. Limestone, marble, and sandstone are the three most frequently used materials for stone containers because they are the easiest durable stone to work. Containers made of granite or other extremely hard stone are generally so expensive as to qualify as objets d'art and are seldom actually used for anything as mundane as plants.

    Stone and the less costly cast stone and concrete containers are durable and stay cool, even in the hottest days of summer. They make ideal containers for public areas where less heavy containers might "walk off." Be sure to choose the site carefully; once you put them in place and fill them with soil and plants, these containers are very heavy.

HOORAY FOR HYPERTUFA

    One stone substitute deserves special mention: hypertufa. Once the exclusive playthings of rock gardeners, hypertufa containers are becoming more popular for a wide variety of plants. The material originated to mimic the old English stone sinks that were used to provide choice little alpine plants with high-and-dry growing environments through damp English winters. The original sinks are now nearly impossible to find, and discarded porcelain or stainless steel sinks just don't have the same charm. Hypertufa to the rescue! This simple formula makes an ideal container for growing plants—roots may actually grow into the pot's walls.

    Hypertufa containers are usually low, wide troughs. We made several of these many years ago, and they remain in fine shape. Many older troughs were made over a chicken-wire or hardware-cloth foundation, but we've found that these often chip, and sometimes large chunks fall off, exposing the wire.

    The simple hypertufa mixture can be shaped or molded into a variety of sizes and shapes, including some very presentable imitations of stone sinks. Wooden molds or plastic-draped bowls may be used as well. The wooden molds generally consist of two parts, one slightly larger than the other. If you're handy with a miter box, you can make molds with sloping sides.

    We opted for the simpler method of plastering the hypertufa over inverted mixing bowls and roasters covered with plastic sheeting. We ended up with a little more "character" to some of our troughs than we'd intended, but nothing we couldn't live with.

    Troughs are generally 1 to 2 inches thick and at least 4 inches deep. Before the hypertufa is completely set, make drainage holes about 1/2 inch in diameter in the container bottom; in large, flat troughs, make several.

    After unmolding but before the hypertufa is completely dry, a light touch-up with a wire brush will disguise any surface imperfections, and a quick once-over with a butane torch will fuse any straggling bits of fiberglass and create an interesting surface texture by melting some of the perlite grains on the surface. Not everyone keeps a butane torch in the potting shed, but it's worth borrowing one when making troughs. Although hypertufa containers will probably not last for centuries like the old stone sinks, they're a whole lot lighter and easier to move.

BEYOND PLANTS, POTS, AND SOIL

    Anyone who cooks has probably heard this lament at least once: "I'd love to start cooking, but I don't have the right equipment." A good cook's usual response is, "Start cooking, and you'll get the equipment you need."

    The same is true for container gardening. To start, all you really need is plants, pots, and soil. Almost anything else is superfluous. Once started, you'll begin acquiring the tools that make the job a little easier. By then, though, you will know a lot more about what you really need and what will work.

    That said, some acquired wisdom can be passed along to beginning container growers and shared among experienced ones. First, anyone who gardens will have most of the basic equipment for container gardening.

    When beginning container gardening, get a couple of good, big covered trash cans. We keep one near the garden hose, and when we bring home a new batch of clay pots, in they go. As soon as we're ready to plant, we remove the pots that have been soaking and throw in the next set—no waiting. Otherwise, we keep the cans covered for the safety of critters in the neighborhood.

    We keep a second can for soil storage and mixing. The lid keeps the soil dry and sweet until we're ready to begin filling pots. A trash can is also a great place to wet down potting soil before filling the pots; purchased potting soil often pours out of the bag as dry as bug dust. Once planted, it is almost impossible to wet thoroughly. It must be thoroughly mixed with water but not made into mud.

    On the other hand, some manufacturers sell soil that is heavy with water. Potting soil and all of the ingredients for making it are sold by volume and not by weight, so don't be taken in.

    We also keep a large trowel handy for filling pots. A plastic container will do the job if nothing else is handy, but a large trowel makes short work of mixing and wetting potting soil. It's also useful when transplanting plants into the containers.

    Invest in a good trowel. Don't fall for the pretty painted trowels sold in the supermarket, shopping malls, and, it seems, street corners, every spring. These lightweight little numbers, when grabbed to dig up something that is far beyond their capabilities, promptly bend in half. Before we discovered the value of a good trowel, we amassed a huge collection of bent ones in the potting shed. As with all other gardening tools, our best advice is to decide what you can afford and then buy the next grade up.

    Our small border spade fills large pots quickly. If growing in containers is your only foray into gardening, this tool might seem extravagant, but if you do enough gardening to justify one, you'll appreciate it. We use ours like a giant trowel; it's far easier to wield than a full-sized shovel. If you can't quite bring yourself to buy one, try dropping a few hints around the holidays.

    Good cutting tools are probably next on the container gardener's shopping list. These accessories range from basic, utilitarian utensils to extravagant ones. We use our fingernails, scissors, paring knives, pocketknives, and almost anything else that will cut to tackle all sorts of chores. If you're like us, by the time your herbs have grown big enough to harvest and use, your fingernails are completely gone. If you use your scissors and paring knives for their intended purposes, you may not want to use them to hack at your plants, too.

    So you really do need something to cut plants with; you need pruners. These tools, like trowels and spades, come in all grades. A pair of utility pruners (or secateurs if you're French, British, or Martha Stewart) can be found in almost any gardener's toolkit. These work just fine for container gardening.

    Last but not least on the tool list are watering accessories. Anything that does not leak too badly can be used to get water to a plant in an emergency, and we've used some strange watering cans on hot days to save new transplants from death. For growing herbs outdoors, we rely on a good garden hose and a water breaker. We spent years using cheap garden hoses that lasted only a couple of years. When a friend gave us our first good garden hose, we quickly replaced all of our cheap hoses with good ones.

    We do all of our watering on the patio with a water breaker—a hose-end attachment that breaks the heavy torrent of a garden hose into an extremely soft shower. There are several types available, but most use the same type of water breaker, an aluminum-encased plastic spray head about 2 inches in diameter with dozens of fine holes. Most commercial greenhouses use them because they work extremely well.

    A good water breaker is essential to our getting all the containers watered in a hurry without damaging the plants. Although the garden hose is on full blast, the stream is gentle enough for all but the youngest seedlings. We attach our water breaker to the end of an aluminum wand to reach plants in the back of the container garden; it improves our aim and makes spot watering more precise.

    We also use a host of watering cans for plants in the house during winter and for fertilizing plants on the patio during the summer. In a pinch, any handy container will do, but a can or pitcher used only for liquid fertilizer or root-stimulator solutions is a must to prevent contamination.

    Plastic and galvanized cans work equally well. The newer impact-resistant plastic cans can withstand tremendous abuse without springing leaks. Galvanized watering cans, however, have a good, solid sense of permanence. We keep a pair of 1 1/2-gallon watering cans and a 1-gallon plastic one in the house all winter. Trips to the faucet quickly become tedious with smaller cans, and larger ones are unwieldy.

    We use cans with long spouts for watering the many pots we winter over on the porch. Our large galvanized cans have brass roses that produce a fine spray for fertilizing pots on the patio. The smaller plastic can comes in handy for watering small pots in the house.

    For the water-soluble fertilizers applied during the summer, we rely on a hose-end fertilizer attachment that meters out the fertilizer, saving the effort of measuring it for every can of water. Ours comes with its own water breaker; at least one brand comes with a perfectly adequate plastic breaker that fits a standard garden hose coupling.

HYPERTUFA RECIPE

    Making hypertufa planters is as much fun as making mud pies and lots more productive. These planters are economical, attractive, and tough as nails, even in regions with harsh winters. Like mud pies, hypertufa is warm-weather fun because the material must not be allowed to freeze until it is thoroughly dry.

    Start small when making planters. Use a large mixing bowl, a six-pack cooler, or similar-sized object as a mold. Protect your working surface with a sheet of heavy plastic. Turn the mold upside down and cover it with plastic, too.

    We mix our hypertufa in a wheelbarrow—it's easy to rinse out. A couple of quarts of portland cement is a good quantity to start with; later you will get a feel for how much hypertufa will cover a particular size and shape of mold. Pull on your rubber gloves and your dust mask and start mixing.

One part portland cement
Three parts peat moss
Two parts perlite
Handful of fiberglass Fibermesh or similar product
Concrete colorant to taste (optional)
Water

    Mix dry ingredients well. Add just enough water to make a thick paste.

    Pat the mix around the bottom of the mold and begin working up. For a mixing- bowl mold, it can be about 1/2 inch thick, but larger molds require proportionately thicker walls. Press the mixture firmly onto the mold; make sure no air holes remain.

    When you get to the top of the mold (which will become the bottom of the pot), make some holes for drainage and set dowels in them. Every day, wiggle the dowels a little so they will be easy to remove when the hypertufa is dry. After 4 to 8 hours, use a wire brush or another tool to add surface texture to the form.

    Cover the form loosely with plastic so that it dries slowly. For the first few days, spritz the surface with water for even drying. Small containers can take a week or so to dry; large ones take three weeks or longer.

    If you can't find Fibermesh or a similar fiberglass product, you can construct a wire foundation for the planter, but the fiberglass is well worth searching out. It's especially important to include it for strengthening large pots.

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