Growing houseplants is a rewarding and popular hobby. Indoor plants help create a welcoming, calming, aesthetically pleasing environment in homes. Plants have been shown to make people more creative and productive, improve their overall health, improve indoor air quality, and make people happy!
Follow these tips to successfully grow healthy and attractive houseplants.
Understanding the environmental conditions in your home is key to growing houseplants successfully.
Unlike the outdoor garden, the indoor environment is completely under the gardener’s control. Once the indoor environmental conditions are known, you can either match plants to the conditions or change the conditions to match the plant’s needs.
For most indoor gardeners, light is the most limiting environmental factor for growing houseplants and therefore becomes one of the most important considerations. The light levels in even the most well-lit indoor space are far less than in any location outside. Many of the plants typically grown as houseplants are understory tropical plants. These plants are used to the dark and shady forest floor and this ability to grow in low light is what makes them great indoor plants.
Light intensity refers to the amount or quantity of light available to the houseplant. Most houseplants – even those that do well in low light – will grow and look their best when provided with bright indirect light indoors. This is light bright enough to cast a distinctive shadow but does not have sun rays hitting the foliage directly.
There are many factors that influence the amount of light that comes through a window.
- Direction - Often south or east-facing windows provide the most abundant light. West-facing windows also provide abundant light but for somes species it may be too intense. North-facing windows are also options for low-light plants that can grow well even without bright indirect light. It is important to note that there is a lot more that influences the amount of light that comes through a window than which direction it faces. South or east-facing windows are not universally better than west or north as many of the other factors, such as those listed below, can also influence the amount of light that comes through the window.
- Distance - Indoor plants closer to the window will receive more light than those further away. Light levels drop quickly as you get further away from the window. Often areas more than a few feet from even bright windows will have light intensities that are too low to successfully grow houseplants. Areas just to the side of windows are also much darker than they appear.
- Window Size - larger windows will let in more light than smaller ones. They have the added benefit of providing more space to grow additional plants!
- Window Coverings - curtains and sheers can greatly reduce the amount of light. Films, tinting, or other coatings also reduce light levels. Some films also filter out important wavelengths of light used by plants. Reduce or remove window coverings to increase light levels.
- Roof Overhangs - the depth and height of roof overhangs just outside the window can change indoor light levels. Overhangs typically have more effect on light intensity at different times of the year as the sun is lower on the horizon in winter months and higher in the sky during the summer.
- Outdoor Plantings and Structures - Trees, shrubs, neighboring buildings, walls, or fences can all reduce the amount of light that enters a window. Light levels are reduced the closer these outdoor obstructions get to the window. Occasionally structures can be reflective and bounce additional light indoors. This is rare in most residential areas but is possible around the reflective glass structures sometimes found in urban or commercial areas.
Light meters, smartphone apps, and even older SLR cameras can be used to measure light intensity. They typically measure light intensity in lumens or footcandles. While these gadgets can be helpful in determining what indoor plants will grow well, most home gardeners have success simply by experimenting. Try a plant in a particular window or location and if leaves drop, flowers fail to develop or growth is pale, spindly, or slow, then light levels may be too low. If leaves are bleached or damaged, or if they turn yellow or brown and drop, light levels may be too high. Change things up by moving different species to different windows or trying new species in a particular window until you find a pairing that works.
The quality of light refers to the wavelength of light. Plants utilize certain wavelengths of light more than others to photosynthesize and grow. These wavelengths are primarily in the red and blue parts of the spectrum. Sunlight provides these wavelengths in abundance. Window coverings and films, as well as other obstructions outside, occasionally change the amount of certain wavelengths that come in through the window. Since sunlight provides all of the wavelengths a houseplant needs to grow well, the quality of light is not a factor that requires much consideration when growing plants on a window sill. Light quality becomes a very important consideration if supplemental light is being used.
The duration refers to the length of time a houseplant is exposed to light. Some plants are photoperiodic and require a certain length of time exposed to light (or day length) to flower or fruit. For these species, providing the right amount of time they are exposed to light is important to get flowering. Sometimes when light intensity is low, increasing the duration can help make plants healthier. While it is not a fool-proof strategy, unhealthy plants in low light may show a slight increase in health by increasing the day length. In most cases, it is more effective to improve the other factors like window direction, size, or distance from the plant to increase light intensity rather than simply provide the same quantity of light but for a longer period.
If you can’t seem to find a window in your home that provides enough light to grow the houseplants you want to grow, then supplemental light will be needed. Learn more about providing supplemental light to indoor plants in this publication: Lighting & Houseplants (pub)
Soil is an important consideration because it influences the amount of water and nutrients available to the plant. The "soil" used for houseplants is actually a mix of various soilless components. Because it is not made from actual soil, it is often referred to as media, substrate, potting media, growing media, or simply as potting soil.
Potting Soil Components
Most houseplant substrates include a mix of two or more components. Commonly used components in soilless media include sphagnum peat moss, perlite, vermiculite, coir (coconut husk), bark, sand, and cocoa hulls. These components are mixed at various ratios to provide the perfect balance of water, air, and nutrient-holding capacity to keep roots healthy. Some of the components are organic and retain water like peat moss and coir. Others help improve drainage like perlite and vermiculite.
Avoid Garden or Field Soil
For houseplants, the growing media rarely includes actual garden soil. Un-amended garden soil is not recommended for houseplants. Garden or field soil behaves differently when you put it into a container. It becomes very compacted and poorly drained. Occasionally you will see potting media include pasteurized garden soil along with other components like perlite or sand, but this is not common and the garden soil is always amended with other components to improve drainage and air-holding capacity.
Finding the Right Mix
While it serves the function and looks a lot like soil, potting media contains a variety of soilless media that provide the perfect balance of water, air, and nutrient-holding capacity to keep roots healthy. Changing the ratio of these soilless media components allows you to create a potting media that is perfect for the indoor plant you are growing. While you can mix or create your own potting soil, most home gardeners will use pre-made potting soil. Acquiring all the components and mixing them can be expensive, time-consuming, and messy. For nearly all indoor plants a general, all-purpose potting soil will work. Some types of indoor plants, such as orchids and succulents, do benefit from specialized mixes.
There are many materials containers are made from including plastic, terracotta, glazed ceramic, and even things like glass, metal, fiber, or pulp. The most common are plastic, glazed ceramic, and terracotta.
Plastic containers are inexpensive, lightweight, and come in a wide range of styles and colors. Terracotta is a classic material for plants. It is sturdy, attractive, and widely available. Terracotta is porous which allows it to dry out more quickly than containers made from plastic or glazed ceramic. This makes it good for plants that like drier soil conditions, like succulents, or help reduce issues with wet soils caused by over-watering. While each container material has some benefits and drawbacks, they all work for plants when used appropriately so which you choose is largely personal preference.
When it comes to container size, bigger is not always better. It’s important to find the right balance between having a container large enough that it doesn’t always need watering but small enough so that potting soil and roots dry out in a reasonable amount of time and are not sitting for long periods in wet soil.
Containers Must Have a Drainage Hole
All containers must have a drainage hole. Without one, the soil stays wet and roots rot and die. Putting a layer of gravel in the bottom does not make up for the lack of a drainage hole.
If you have a container you want to use, but it doesn’t have or you don’t want to add a drainage hole, use a double-pot system. Double pots (or cache pots) use the desirable container as an outer “sleeve” for a slightly smaller container that does have a drainage hole to set down inside. This allows you to get the drainage you need while using a container that doesn’t have a drainage hole.
Trays and saucers are beneficial for protecting furniture and floors. Just like cache pots, they help collect excess water. Never allow the plant to sit in trays or containers full of water.
Most houseplants prefer a root ball in slightly cramped quarters so frequent repotting is not always needed. You will know it's time to repot when plants become top-heavy, growth slows, and/or potting soil quickly dries out. Over time, potting soil will break down and become more compacted and poorly drained. This is another indication that it is time to repot.
When repotting, only move up a size, maybe two. Houseplants do not benefit from moving from super cramped quarters to enormous pots. Pick broad wide-based pots for taller plants so they will be stable and less likely to tip.
Potting or repotting can be done any time of the year, although most gardeners have the best success doing it in late winter or early spring as houseplants start growing more vigorously with the warmer temperatures and longer days of spring. Follow these directions to repot a houseplant:
- Remove the plant from the old container.
- Squeeze the sides of plastic pots to loosen the root ball or run a knife around the inside perimeter of the pot to make it easier to pull the root mass from the old container.
- Loosen the root mass, lightly break-up the soil, and remove any limp, brown, or dead roots.
- Place a small amount of soil in the bottom of the new container.
- If needed, a small screen or broken pottery shard can be placed over a large drainage hole to prevent soil from falling out. In most cases, they are not needed and may clog or greatly slow the drainage of the pot.
- Do not put gravel or rocks in the bottom of the container. This effectively creates a wetter zone of soil closer to developing and growing roots which promotes root rot.
- Place the root mass in the container and fill in around the root ball with fresh potting soil. Lightly firm the soil around the root ball to hold the plant in place.
- The top of the soil should be at least 1/4 to 1/2 inch lower than the rim of the container. This creates an area for water to pool and soak in making the process of watering easier.
- Thoroughly water the plant.
- Wait at least 2 to 4 weeks before you begin regular fertilizing. Most potting soil contains a small amount of fertilizer so it is not needed.
Ideal Temperature Range
While many houseplants are from tropical parts of the world, they do not require tropical temperatures. If you are comfortable, your houseplants will be too. Temperatures between 65 and 75°F are ideal for most indoor plants. Houseplants will tolerate slightly lower temperatures but avoid temperatures below 55°F. While most homes will not be this cold, this is important to remember if you go on vacation during the winter months.
Most houseplants prefer a drop in temperature from day to night and some will require it to flower. This daily temperature fluctuation should be about 10 to 15°F from day to night.
Avoid Temperature Extremes
Anytime a houseplant is exposed to a big swing in temperatures, yellowing, browning, wilting, or leaf drop can occur. Keep indoor plants away from drafts such as the warm draft from a heat register or the cool draft from the front door opening in winter. Avoid trapping plants between the curtain and windowpane where temperatures in the sun of the day can get very warm and then quite cold in the middle of the night.
In winter, always take special care to protect houseplants while transporting them from the store to your home. Purchase houseplants at the end of the shopping trip and get the plant as quickly as possible to a heated vehicle. Always transport the houseplant in a plant sleeve or carefully wrap it before going outdoors. Most garden centers and greenhouses will wrap the plant for you but many grocery or big box stores do not. You may have to request a bag or sleeve to wrap the plant yourself. Exposure to freezing temperatures, even for a brief moment, may cause damage such as wilting, browning, or leaf drop and in extreme situations can kill the plant.
Most indoor plants are from tropical areas and they grow best in high humidity (40 to 50%). Most of our homes have very low levels of relative humidity, especially in the winter (as low as 10% in the winter). This low humidity can lead to slow growth, dried-up flower buds, and brown leaf tips and edges. Increasing the humidity, especially in the winter months, can encourage healthier growth and better-looking plants.
Misting Isn't Very Effective
Misting is often thought of as a good way to raise humidity and keep plants healthy, but in reality, it does not raise the relative humidity around the houseplant. Misting can also easily promote and help spread certain diseases. When done with care, misting can be used for other reasons. Some houseplants can absorb a little bit of water through their leaves and benefit from occasional misting. Misting can also be very helpful for cleaning dust off the foliage which improves appearance. However, misting does not raise humidity levels for more than a few minutes making it an impractical and ineffective way to raise humidity.
Methods to Raise Humidity
One of the easiest ways to raise humidity is to group plants together. Simply putting plants close together raises the humidity around these plants because the collective foliage helps trap humid air around the leaves.
While more expensive to purchase and operate than the other options, humidifiers are very effective at raising the humidity. They have the added benefit of making the entire room more humid making you happy during the dry winter months as well.
Pebble trays are shallow trays of water with rocks or some other structure in them to keep the bottom of the pot above the water level, but allow the water in the tray to evaporate and raise the humidity around the plant. Just be sure the bottom of the pot is not in the water, or the soil will never dry out and the plant will develop root rot.
Finally for smaller plants utilizing a terrarium is an excellent way to raise humidity. These enclosed glass cases help trap and hold moisture in the air. They have the added benefit of often being attractive too.
Watering is both the easiest and most difficult part of growing houseplants. Watering properly is essential to good houseplant health. Improper watering is the number one reason people have problems with houseplants. Proper watering requires more thought than simply watering every Saturday as the frequency and amount of water you give a plant depends on a lot of different factors. Ideally, the potting soil is allowed to dry out completely between waterings but the plant is not allowed to wilt. Then the soil is thoroughly saturated with the excess water allowed to drain away. This wet-dry cycle of the potting soil promotes healthy roots and therefore healthy plants.
When to Water
It is very easy to overwater houseplants. This is because watering frequency changes depending on things like light levels, temperature, humidity, type of soil and container, plant size, species, and time of year. When you water on a regular schedule, like every Saturday morning, for example, you are almost always providing too much water for some plants and not enough for others. Instead, you should check for water on a regular basis.
Many strategies can be used to determine the appropriate time to water. The easiest and most reliable method is to simply touch the soil with your finger. If the soil is dry to the touch down an inch or so, it is time to water. If it feels wet, wait and check again in a day or two. Moisture meters can be used instead of touch, although they cost more than your finger! Other strategies that can be used to determine when its time to water include, the weight of soil/container (it will weigh less when dry), soil color (it will be lighter in color when dry), foliage color (many plants turn a slightly dull color when dry), and observing a slight wilt in the foliage. Often utilizing a combination of these factors is best to insure it is time to water.
How to Water
When water is needed, water thoroughly until water drains out the bottom. This helps to insure the entire root ball is fully saturated. Often it is easier to move the plant to a sink or tub to apply water and not run the risk of having water spill or drain out over floors and furniture. When potting soil gets too dry it can be difficult to re-wet and the water may just run off, around, and out the bottom of the container rather than soaking in. In this situation, water several times to thoroughly wet the root system. You can also submerge the root ball in water for 30 or so minutes to allow the potting soil to soak up the water.
Always remove any excess water that remains in the saucer or outer pot after about 30 to 45 minutes. Never allow plants to sit in water. Roots that stay in water for long periods will rot.
Nearly all municipal sources of water and well water are fine for nearly all plants. If it is safe to drink, it can be used on most indoor plants. The ideal water for most plants is rainwater. Water collected from rain barrels is appreciated by houseplants, but not always available.
If the water in your home is heavily softened, it is possible to see a build-up of salts in the soil, especially with those plants that are not frequently repotted. The water from a dehumidifier is fine to use for most houseplants as well, but if it's used extensively over a long period of time it can lead to a build-up of metals (such as aluminum, copper, or lead) in the soil. Excess salts and metals can cause symptoms that look much like over-fertilization. Regular repotting as well as watering thoroughly allowing the water to flush the soil can help reduce the build-up of salts and metals.
On highly sensitive species, like many carnivorous plants, distilled water may be the best water source to avoid damage from the minerals, salts, and other contaminants in the water.
While most indoor plants benefit from fertilizer, they don’t need a lot! More fertilizer means more growth and sometimes the light, humidity, or moisture levels may not be high enough to support that much growth resulting in spindly or weak growth. Plus more growth means more cutting back, repotting, and houseplants that more quickly outgrow the indoor spaces you have.
When to Fertilize
Fertilize only when houseplants are actively growing. Many have a period of rest, usually during the short days of winter, so reduced fertilization is needed during this time. Most houseplants are best fertilized once or twice a month starting in March or April through November or December. Most potting mixes contain a small amount of fertilizer so for the first few months after repotting, little or no fertilizer is typically needed.
Types of Fertilizer
Fertilizer comes in many forms including water-soluble or slow-release as well as organic or synthetic. They all provide nutrients that plants can use so which type you use is largely a personal preference. Water soluble fertilizers dissolved in the water are great because you can change the amount and frequency you fertilize throughout the year. Slow-release fertilizers are great because they can be sprinkled on and don’t require extra work throughout the season. You can buy fertilizers specially formulated for houseplants or utilize balanced, all-purpose fertilizers, which are those fertilizers that have a fertilizer analysis where the three numbers are relatively equal like 10-10-10. When using general, all-purpose fertilizers, mix them at half or quarter the strength outlined in the instructions because houseplants grow slower than the outdoor plants the instructions on the fertilizer box are written for.
- How often should houseplants be watered during the winter months?
- How often should I fertilize houseplants?
- What is the proper temperature for houseplants during the winter months?
- The air in our home is extremely dry in winter. Should I mist the houseplants?
- Dust has accumulated on the foliage of my houseplants. How can I clean the plants?
- Will standard fluorescent bulbs provide sufficient light for houseplants?
- How and when do I bring my houseplants back indoors before winter?
- Do houseplants actually improve indoor air quality?
- One of my houseplants has small, yellow mushrooms on the surface of the potting soil. Will the mushrooms harm it?
|Care of Houseplants
Part 1: Water and Fertilizer
|Care of Houseplants
Part 2: Containers and Soilless Media
|Care of Houseplants
Part 3: Temperature and Humidity
|Care of Houseplants
Part 4: Lighting
- Propagating Houseplants
- Growing Plants Under Supplemental Lights (link coming soon)
- Moving Indoor Plants Outside for the Summer
- How to Create and Care for a Terrarium
- How to Create a Dish Garden (link coming soon)
- Diagnosing Houseplant Problems
- Growing Orchids Indoors
- Growing Succulents Indoors
- All About Air Plants
- Improving Indoor Air Quality with Houseplants