This concise Storey BASICS® guide teaches novice gardeners how to successfully keep indoor plants beautiful and healthy. Learn how to choose the best plants for your home and what each species needs in terms of location, water, sunlight, and fertilizer. Covering the basics of repotting, pruning, and dealing with pests, Ellen Zachos shows you how to keep your houseplants looking vibrant for years to come. Soon, you’ll be watching over a collection of thriving plants that add a lively dose of color to your home.
About the Author
Ellen Zachos teaches foraged mixology workshops to bartenders in partnership with Rémy Cointreau USA, and is a regular contributor to several Edible magazines. A longtime instructor at the New York Botanic Garden, Zachos is the author of six books, including The Wildcrafted Cocktail and Backyard Foraging. She shares wild, seasonal recipes at backyardforager.com.
Read an Excerpt
Give your plants a few basics and they'll be happy. Good light, adequate water, and nutritious soil are all they really need.
Light: How Much Is Enough?
If you're going to understand only one thing, it should be light.
How much light does a plant need? That's the first, most essential question you must ask yourself before bringing any new plant into your home. If you can't give it the light it needs, the plant is doomed. Doomed, I tell you!
Often, houseplants will be labeled low-, medium-, or high-light plants. These may sound like grossly general categories, but they're actually pretty helpful.
* Low light: Northern exposure; obstructed eastern or western exposure; room interior
* Medium light: Eastern or western exposure; this may be either bright, indirect light or a few hours of direct sun
* High light: Unobstructed southern exposure; 6 to 8 hours of full sun
Of course, nothing is cut and dried. You'll have to decide for yourself whether the blue spruce in front of your west-facing window turns your sill into a medium- or a low-light location. Every growing situation is individual, but the above categories give you a place to start.
How do you further define what kind of light you've got? Choose a method based on your personality. Are you a technophobe? Use the shadow method. If you're an equipment geek, use your camera or buy yourself a light meter. Either way, with time you'll develop a feel for light intensity, and ultimately, you'll be able to judge with your eye alone.
Shadow method. The shadow method requires nothing fancier than your eyes and a hand. On a sunny day, turn out all the lights and hold your hand about a foot above the spot (or table) where you want to grow your plant. If you can see a dark, sharply outlined shadow for 6 to 8 hours, you have a high-light location. (You don't have to stand there the whole time, but do check on your shadow every hour or so.) If you see a shadow with slightly blurred edges, you have a medium-light location. A faint shadow with fuzzy edges indicates low light. No shadow at all means you need supplemental light to grow here.
Using a camera or light meter. If you want to be more precise in your measurements, you'll need to understand foot-candles. A foot-candle is an approximation of the light given off by one candle at a distance of 1 foot. High-light plants need approximately 3,000 foot-candles, medium-light plants need between 1,500 and 3,000 foot-candles, and low-light plants need about 1,000 foot-candles. That said, plants are highly adaptable creatures and will often pleasantly surprise you by blooming even when light conditions aren't optimal.
If you have a single-lens reflex camera, you can use it to measure foot-candles. Set the film speed to ISO 25 and the shutter speed to 1/60th of a second. Place a white sheet of paper in the spot where you want to measure and place your camera 2 to 3 feet away. Focus on the sheet of paper, and read the f-stop for a correct exposure. Use the chart below to find the approximate foot-candles that correspond to your f-stop reading.
If this seems like too much work, or if your inner geek secretly wants to buy another gadget, get yourself a light meter that measures in foot-candles. A decent meter will cost between $50 and $100 and will give immediate, accurate readings with the flip of a switch.
Let's pretend you failed the shadow test. Even if you get no natural light at all, you can still have an indoor garden; you'll just need a little extra equipment. Before you decide what kind of equipment, consider these three characteristics of light: intensity, color, and duration.
Intensity. Light that seems bright to the human eye is not necessarily intense enough for optimum growth of tropical plants. Low light intensity may not kill a plant, but it can result in weak growth with elongated, spindly stems. Without adequate light, plants will not fruit or flower.
Color. The sun emits light in all colors of the visible spectrum: red, orange, yellow, green, blue, and violet. White light is a combination of all of these. However, not all colors of light are equally valuable to plants. Light in the blue and red ranges is most important for plant growth. Flowering plants require large amounts of orange and red light to bloom and set fruit, and light in the blue range promotes lush, compact foliage. Grow lights are special bulbs designed to deliver specific wavelengths of light necessary for plant growth.
Duration. This refers to the number of hours of light a plant receives per day. Since artificial light doesn't exactly duplicate the intensity and color of sunlight, you can compensate by giving plants more hours of artificial light than they would receive outdoors in their native habitats. Increased quantity compensates for reduced quality, and duration is easily regulated by including a simple timer in your grow light setup.
So what kind of grow bulbs should you use?
Fluorescent lights are inexpensive and require no special wiring or installation. The most common type of fluorescent tube is the cool white bulb, which emits a bluish light. Warm white tubes emit more light in the red end of the spectrum. Seeds can be started under cool or warm white bulbs, and many foliage plants can also be grown successfully under these lights. Use one of each in a double-tube fixture for a good balance of useful light.
For a little more money, there are special full-spectrum fluorescent tubes engineered to provide light in the wavelengths most useful to plants (the blue and orange/red ranges). To the human eye, the light given off by these bulbs is similar in color to that of the noonday sun. They cast a pleasant light in your dark living room. However, there is some controversy over whether these bulbs are worth the additional expense. Many growers believe that a combination of the less expensive cool and warm white tubes is equally effective. If you are just beginning to experiment with growing under fluorescents, start with the less expensive bulbs and see how you do. If your plants grow well but you don't like the visual quality of the light itself, consider buying the full-spectrum bulbs.
Because fluorescent lights give off very little heat, plants can be placed close to the bulbs (5 to 6 inches) without risk of burning. Fluorescent tubes produce less light at the ends of the tubes than at the center, so plants requiring less intense light should be placed under the 3 inches of tube at either end of the fixture. Fluorescent tubes should be replaced every 12 to 18 months if they are being used approximately 14 hours a day.
Incandescent grow bulbs are less efficient than fluorescent grow lights, since much of their energy is given off as heat, rather than as visible light. On the plus side, they can be used in many common household lamps, and they are adequate for certain low-light foliage plants. A 60-watt bulb at a distance of 2 feet will provide approximately 20 foot-candles of light. At this low light intensity, growth will not be rampant, but certain low-light species can be maintained under these conditions.
Incandescent grow lights can also be used to boost the brightness of a partially obstructed window, increasing the number of plant species you can grow. Track light fixtures can be fitted with grow bulbs to brighten a larger area. Since incandescent bulbs are hot, don't place them too close to foliage or it may burn. A minimum distance of 18 to 24 inches is recommended.
High-Intensity Discharge Lights
High-intensity discharge (HID) lights are the brightest grow lights available. There are two subcategories of HID lamps: metal halide (MH) and high-pressure sodium (HPS). Each produces a different color of light determined by the blend of gases contained in the tube at the center of the bulb. You can use a combination of MH and HPS lamps in a single location, but a metal halide bulb cannot be used in a high-pressure sodium fixture, and vice versa (the bulbs have different electrical requirements).
Both metal halide and high-pressure sodium lights emit more intense light than fluorescent or incandescent lamps. They operate with regular 120-volt household current but require special fixtures, so this isn't a bulb you can just plug into your favorite lamp. These fixtures tend to be industrial in appearance.
Also, consider the location of your interior landscape as well as what you want to grow when choosing your HID lamp. Metal halide and high-pressure sodium lamps produce very different colors of light, which promote different types of plant growth.
Metal halide. These bulbs give off light that is strongest at the blue end of the spectrum. This light produces compact, leafy growth and is preferable when your light garden is an integral part of your home, since the light won't distort the colors of the plants (and people) it illuminates. Metal halide bulbs are less expensive than high- pressure sodium lamps, but they need to be replaced more frequently — about once a year. If you're growing plants mainly for their foliage, this may be the best choice for you.
High-pressure sodium. These bulbs last about twice as long as metal halide lamps but cost slightly more per bulb. They emit a strong light at the red/orange end of the spectrum and promote flowering and fruiting. If your goal is lots of blooms, use high-pressure sodium lamps, but remember, their light has a strong red/orange cast and distorts the colors of everything and everyone it illuminates.
Light-emitting diodes (LEDs) are the newest entry in the grow light market. Large commercial units can be highly effective, comparable to HID lights. Such units are expensive to buy (think hundreds of dollars) but not to operate, since LEDs use very little electricity. Small household LED units have several things to recommend them. Their light is much more intense than that of fluorescent tubes, and they are quite efficient, losing little energy to heat. Plants can be placed close to the bulbs (12 inches) without risk of leaf burn. Their light is attractive, and the bulbs can be used in household light fixtures. Since LED bulbs are spotlights, rather than tubes, they are better suited for single plants or small groups, while fluorescent tubes cover more growing space.
If you're just beginning to experiment with artificial light, start with LEDs or fluorescent tubes — whichever suits your growing space. If you're thrilled by your success, you may decide to invest in an HID system, in which case you'll be able to grow a wide range of houseplants, no matter what your natural light levels are like.
Water and Humidity: Getting It Right
Watering a plant sounds like a simple task, but it requires some thought. Over-water and you kill the plant. Under-water and you kill the plant. The symptoms of both can look bewilderingly similar. In essence, what happens is the same. When a plant is under-watered, its roots don't absorb enough water and the plant shrivels and dies. When a plant is over-watered, its roots rot and the plant can't absorb water or nutrients. It shrivels and dies.
It's possible to grow some houseplants without fully understanding the concept of watering; certain plants are quite forgiving of less-than-perfect watering schedules. Casual growers may make lucky guesses, learn a schedule by rote, or depend on devices like moisture meters to tell them when it's time to water. But if you truly understand how to water a potted plant, your indoor garden will be healthier and more beautiful. And who wouldn't want that?
Understanding How to Water
There is no set schedule to memorize, but there are several simple concepts to master. By understanding how a plant uses water, as well as what affects the rate at which water is used, you can assess the needs of each plant in your indoor garden.
Water enters a plant through its roots, travels up through the plant's vascular tissue to the leaves, and is released to the air. This is called transpiration. Water molecules leave the plant's foliage through osmosis — the passage of water from an area of high water density to an area of low water density. This water, in the form of vapor, passes through openings on the underside of plant leaves, called stomata, as a product of photosynthesis.
Everyone who gardens indoors knows that plants need water, but not everyone understands why the amount of water is important, so let's start there. Plants in the ground have a large amount of earth through which their roots extend in search of water and nutrients. Plants in containers have a very limited amount of potting mix from which their roots can draw water and nutrition.
The amount of potting mix in a container determines how much water can be retained. Water molecules adhere to soil particles, filling the spaces between those particles that hold air when the potting mix is dry. When you water a potted plant, the air spaces between soil particles become filled with water, which is then absorbed by the plant's roots over time. A plant needs both water and oxygen, so it's important to find the right balance in your watering schedule. You must allow the soil to dry out enough to provide the plant's roots with oxygen, since keeping the soil consistently damp may make it impossible for the plant to breathe. That being said, some plants have adapted to soggy soils and grow best in potting mixes that are consistently wet.
It is extremely important to water a plant thoroughly each time you water it. I cannot stress this enough. (Seriously: this is the takeaway.) Thorough watering means watering a plant until water runs through the drainage holes in the bottom of the pot. If a plant is bark mounted or potted in bark mix, thorough watering means soaking the entire plant (pot or mount and all) for 10 minutes in a bowl of water. If you water a plant incompletely, you encourage root growth only in the portion of soil that has been watered. This means that roots grow only through the portion of soil that receives moisture, instead of deeply and throughout the pot.
One of the primary functions of any root system is to provide anchorage for the plant. A plant with an underdeveloped root system will be at a disadvantage because it will not have the ability to absorb adequate water and nutrients from the soil, and it will not be well anchored where it grows. If a root system is confined to the top few inches of a container, it is entirely possible for a top-heavy plant to literally pull itself over and out of its pot. I speak from experience.
Water Cues from Plant Structure
There are numerous ways plants can store and retain water under dry conditions. Some plants have developed a thick cuticle — a waxy layer covering the plant's epidermis. The cuticle creates a barrier between moisture in the plant foliage and the surrounding air, so foliage loses water more slowly via transpiration, and the plant can go longer between waterings. Other plants have thick leaves with storage tissue for holding water in times of drought. Cacti have modified foliage (spines) and specialized storage tissue that allows them to go for long periods of time without water. Conversely, plants with delicate, thin leaves and slim stems lose water more quickly via transpiration.
Look for visual cues to assess your plants' water needs. Even if you don't know what type of plant you have, if it has thick leaves and a shiny, waxy leaf surface, it's a good guess it's a drought-tolerant plant. Peperomias, hoyas, and even some orchids are common examples of succulent, drought-tolerant plants that present these clear visual cues.
Seasonal Water Needs
You may have noticed that most plants require less frequent watering in winter. This is a function of reduced temperatures and shorter daylight hours. In spring, houseplants begin to grow more rapidly in response to longer daylight hours and warmer temperatures. As their growth rate increases, so does their need for water.
Photosynthesis, a plant's means of producing its own food, can be summarized as follows:
Water + Light + Carbon Dioxide = Oxygen + Energy + Nutrients
For the rate of photosynthesis to increase, a plant requires more water, more light, and more carbon dioxide. Therefore, plants require more water as they move into active growth.
Most houseplants are in active growth from spring through fall. Some, however, are in active growth when you least expect it. For example, while most houseplants require less frequent watering in November or December, that is exactly when a holiday cactus blooms, after a period of cool drought. Your holiday cactus will need increased water at this time to support flowering. Your cue will be when you see the first buds.
Excerpted from "Growing Healthy Houseplants"
Copyright © 2014 Ellen Zachos.
Excerpted by permission of Storey Publishing.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.
Table of ContentsPreface
Introduction: Learn to Speak Plant
Part One: Essentials
- Light: How Much is Enough?
- Water and Humidity: Getting It Right
- The Growing Medium
- Fertilization: More Isn't Always Better
- Cool Tools You'll Need
- Repotting: It Has to Happen Sometime
- Good Grooming
- Propagation: Making More Plants
- Vacation for You, Vacation for Your Plants
- Managing Pests
Part Three: Designing the Indoor Garden
- It's All in the Display
- Flowering Plants