Every living organism requires certain things in order to survive and thrive. These necessities are familiar, being the same things that we need on a daily basis. Collectively, light, air, water, nutrients, and space allow us to live a healthy life. Yet, each serves a unique function and purpose in our well-being. Take one away and the delicate balance of our biology is in peril.
As a gardener, I’m often asked in one form or another ‘what does a plant need to survive and grow?’ One crucial aspect is the way plants supply themselves with food. Plants have adapted to do this using a process called photosynthesis, by which plants, shrubs, and trees use sunlight to transform carbon dioxide and water into food.
This is easily visible as the process involves producing chlorophyll resulting in plant foliage turning lovely and various shades of green. But again, without proper light, air, and space, this wondrous process will fail to support the plant.
What Does A Plant Need To Survive
So, plants need light, air, water, nutrients, and space to survive. But, what do each of these things do? Let’s take a look at each one more closely:
Air: Plants absorb carbon dioxide and water from the air and internally convert these into glucose and oxygen.
Light: Plants can’t do the above without the help of the energy from sunlight. Without it, no other life-sustaining process is possible.
Water: 95% of plant tissue is water. Seed germination and growth are fully dependent on it as nutrients are carried through the plant via water circulation.
Food: Plants feed themselves by converting light and gasses into food. When grown in poor soil, we can assist by adding supplemental nutrients to aid in healthy growth. Read Plant Food Vs Fertilizer for an in-depth understanding of photosynthesis.
Space: A plant’s root system and foliage need space to spread out in order to reach the light in the environment and nutrients and water in the soil.
By the way, our site is supported by visitors like you. Some links on this page may be affiliate links which means if you choose to make a purchase, I may earn a small commission at no extra cost to you. Thanks for your support! You can find out more here.
Plant Light Requirements
Access to light is critical to plant health, especially in winter when days are shorter. Vegetables and ornamentals thrive on 12-16 hours of light per day. Shade plants require far less, at 3-6 hours per day. While most common houseplants are right in the middle at 12-14 hours per day.
In spring, summer, and fall, plants naturally get their light from the sun. In winter, grow lights can be helpful to mimic natural sunlight. We’ve all seen plants become “leggy” in low light. These weak stems, along with the leaves, will fade in color as they struggle to photosynthesize. Then ultimately fail in 4 to 20 days. Even low-light plants will begin to show signs after 12 days.
How Do Plant Use Light: Photosynthesis
Plants capture sunlight using their foliage. This, combined with carbon dioxide and water from the air and minerals from the soil, is converted into glucose, starch, and oxygen.
Chloroplasts (leaf cells) contain a green pigment called chlorophyll, providing us with a pretty green plant. This highly-functional feature is what specifically allows the foliage to harness the sun’s energy.
The photosynthesis that follows allows those chloroplasts to multiply. And the circle of light absorption and food production continues on, as the plant grows. The resulting glucose and starch are stored and used as food, while the oxygen by-product is “exhaled” by the plant.
Hours of daylight and Flowering Cycle
All blooming plants have a “flowering cycle”. One that requires consistent light exposure in order to function properly. Some boomers are more particular about their light needs, while others really don’t mind, either way. All of them have been organized into three botanical categories:
Long-Day Plants: These are only able to produce buds after being exposed to long, continuous periods of light. Aster, hibiscus, echinacea, radish, spinach, and various lettuces would fall into this category.
Short-Day Plants: Bud production in these is triggered when daylight grows shorter. Examples are chrysanthemum, rice, soybean, onion, violet, Christmas cactus, and poinsettia.
Day-Neutral Plants: Plants that produce regardless of day length, like corn, tomatoes, chilies, and peppers.
Shade Tolerant Plants
Shade tolerance is defined by a plant’s capacity to thrive in low-light conditions. In the wild, shade dwellers like heuchera, hostas, and all types of ferns have adapted to use the expansive surface area of their leaves and fronds to capture energy from intermittent shafts of light gleaming down through breaks in the canopy.
Smaller shade lovers with less surface area use this to conserve water and produce new shoots. Which are stimulated into quick growth as they reach for the light. Flowering plants, like hydrangeas, fragrant gardenias, and begonias, have adapted to produce vibrant colors in less light.
Plant Watering and Humidity
In order for plants to utilize all of that lovely light, they also require consistent replenishment of water. Without adequate moisture, photosynthesis and food production will not occur as needed. Causing plants to experience stunted or deformed growth and fading color. Followed by a vulnerability to pests and disease.
Water (either from us or rainfall) and humidity are critical environmental factors in the health and vitality of all plants. Stable water circulation allows for the vital distribution of nutrients and keeps pores in the foliage, called stomata, open to allow for photosynthesis.
How Do Plants Use Water
Plants use water to maintain photosynthesis and remain hydrated. But, more importantly, to circulate converted food, and any supplemental fertilizer you give them, from roots to leaves. Which are the primary points of absorption.
Roots draw moisture from the soil, using a process called osmosis, and disperse it to the green chloroplasts in the foliage. Root growth is triggered as they reach out for the water. As the root ball grows, so does your plant.
Water is also crucial to seed germination as it softens the hard, outer casing enough for the tiny seedling inside to emerge.
Nutrients for Plants
From seed germination to seed formation, proper nourishment encourages healthy growth, resistance to disease and pests, and bountiful crops. Nitrogen, phosphorus, and potassium are key elements that play a large part in this effort, also known as an NPK. Secondary trace elements like magnesium, calcium, and sulfur also serve valuable functions. Playing supporting roles in how plants use NPK macronutrients.
It is also worth noting the environmental condition need to be optimal to allow for these nutrients to be processed by the plant. Soil or water pH plays an important role in allowing the available food source to be processed adequately.
N-P-K
Vegetables, ornamentals, and houseplants are happiest when they have access to the right combination of macronutrients such as:
Nitrogen (N): A major contributor in building proteins and enzymes, which are essential building blocks in any plant.
Phosphorus (P): A critical component of the food a plant creates through photosynthesis.
Potassium (K): Aids in the circulation of water, nutrients, sugars, and starches throughout the plant.
Every fertilizer label will display a three-numbered ratio. This is known as the N-P-K of the fertilizer, indicating the proportions of nitrogen, phosphorus, and potassium. For example, a 5-5-2 NPK has 5% nitrogen, 5% phosphorus and 2% potassium. Every plant, tree, and shrub requires a specific NPK proportion in order to thrive.
Nitrogen
Plants grown in fertile soil have easy access to nitrogen, especially when you amend your soil with well-aged compost.
Natural compounds like feathers or blood meal are often added to organic fertilizers and will help to increase nitrogen content as well as fertility.
Using a good quality all-natural and high nitrogen fertilizer such as Down To Earth Blood Meal Fertilizer in fall and early spring will help to replenish the soil ready for the growing season ahead.
Starting at the roots, this vital macronutrient aids in water disbursement and nutrient intake. Using the same proteins and enzymes that it helped to create. In the foliage, nitrogen becomes a key component of green chlorophyll which facilitates photosynthesis.
Phosphorus
90% of the world’s mined rock phosphate is used for agricultural and gardening purposes. This means that fertile soil will contain a significant amount of this natural mineral. Like nitrogen, it aids in plant growth on a cellular level and facilitates root growth. While strengthening the walls of stems and stalks.
In fruit trees and vegetable plants, phosphorus encourages bud formation and nourishes them all the way to fruiting. Promoting a hardy tolerance to severe winters in trees, shrubs, and perennials.
Potassium
Potassium is responsible for circulating water, nutrients, and carbohydrates (starches) throughout plants. It also activates those enzymes that were created by nitrogen and phosphorus to aid in photosynthesis.
In many vegetable varieties, potassium is critical in the final stage of a crop formation. Without it, flowers will struggle to form fruit after fading. And potatoes need it for tuber division and growth. In roses and other flowering plants, this vital nutrient promotes strong stems to hold large, well-developed blooms.
Minerals and Vitamins
Plants require balanced nutrition in order to maintain health and vitality. There are three important “food groups” that plants typically need, with each variety benefitting from different proportions.
Primary NPK: A ratio of nitrogen, phosphorus, and potassium, as previously discussed.
Secondary Trace Elements: These include sulfur, magnesium, and calcium, which aid in the absorption and function of the NPK.
Micronutrients: minerals such as copper, zinc, and manganese that complete a well-balanced nutritional regimen.
Benefits of Minerals for Plants
The right combination of minerals works to support the creation of new cells. Which then form tissue and, ultimately, all of our lovely plants. Without proper nourishment, growth, flowering and fruiting will not take place properly.
Symptoms of deficiency are often visible by the onset of stunted plant growth, yellowing and wilting foliage and stems, and a lack of flowers and fruit. If grown in poor soil, there are a number of organic and inorganic supplements that can help amend your soil and provide for your plants.
How Often do Plants Need Nutrients
How often to add nutrients depends on the fertility of your soil. If well-aged compost is added, then it may be some time before plants absorb all the nutrients within. Standard potting soil may contain fewer nutrients. So, an appropriate NPK will help maintain vitality.
These come in either a fast-acting liquid or a slow-release granule or spike. Liquids need to be applied more frequently. But, following the manufacturer’s recommendations will help prevent overfeeding. Slow-release methods carry less risk of this and typically only need to be applied once or twice per growing season.
Mineral and Vitamin Supplements for Plants
Calcium, magnesium, and sulfur minerals are important in facilitating everything from cell structure to light absorption. Calcium carries NPK nutrients throughout a plant and magnesium is essential for chlorophyll production and photosynthesis. While sulfur triggers the formation of each chlorophyll molecule.
Copper and manganese also assist with photosynthesis and help the plant “digest” the food created from that process. It’s well-documented that people benefit from vitamin supplements, but it remains unclear how much plants do. If you feel adding vitamins to your plants would help, be sure that they are formylated plants and not for people.
Growing Substrates
A substrate is defined as any surface upon which a plant grows. Which can be either soil, water, or, in some cases, just plain air.
Coarse, medium-coarse, and fine soil are the most commonly used substrates from seed germination to harvest. But, many indoor plants will actually grow in plain water because it supports the enzymatic activity necessary for growth. Hydroponic gardening combines water with support materials like rock wool due to its ability to maintain sufficient air space and moisture around roots.
Some plants like orchids and air plants don’t need a substrate at all. They’re perfectly happy growing with their roots spread over tree branches, fully exposed to the air. Absorbing all the moisture and nutrients they need from their environment.
Do Plants Need Soil to Grow
Plants growing in all these different environments make it clear they don’t necessarily need soil to grow properly. They still require support, nutrients, air circulation, and moisture. But, as mentioned, certain plants have adapted to pull these literally out of thin air, typically those native to tropical climates. Provided they have adequate protection from environmental stresses, they will grow and thrive.
Most plants, though, need their roots to be in fertile soil. It will provide support and hold nutrients and moisture in place so plants can access it. In addition to providing adequate aeration and root protection.
Aeration
No matter the growing medium, adequate air-circulation in and around each grain of soil, wood chip, or pebble is an important component of a healthy substrate, as it serves a number of purposes. Homeowners understand the benefits of aerating their lawn every so often. The same applies to plants, both indoors and out.
A Well-aerated substrate reduces compaction, which often happens around dense roots in the soil. This kind of “elbow room” also allows nutrients to reach the roots without any obstruction and makes water and oxygen more widely available. Thus, stimulating easily-expanding root growth and other fundamental processes.
Moisture
Since plants absorb carbon dioxide and water from the air and convert these into glucose and oxygen for sustenance. Adequate moisture is critical. Without consistent watering and environmental humidity, plants can’t feed themselves or stay green. Even with supplemental fertilizer, a lack of moisture leaves a plant without a means to absorb or distribute those nutrients.
Conversely, with soil-based plants, too much water can have fatal consequences. Vital oxygen is flushed from the soil, depriving the plant of air and aeration. Resulting in a blockage of photosynthesis and root rot. A fine balance is needed to maintain healthy water and aeration levels.
What is the Best Soil Mix for Houseplants
The most fertile and supportive soil for houseplants will be a combination of fresh potting soil and organic, well-aged compost. This will provide natural nitrogen, phosphorus, and potassium content that houseplants will thrive in. Not to mention, the inclusion of key minerals, micronutrients, and, of course, beneficial microbes that convert all those nutrients into a form that plants can easily absorb.
The best soil mix will also contain materials such as perlite, vermiculite, and coco coir that will improve aeration and drainage while preventing compaction and moisture loss around the roots.
Soil alternatives
It is possible to grow plants in soil-less, potting mediums, using various organic and inorganic materials. Many gardeners prefer this practice because they can grow their plants in an environment that runs less risk of soil-borne diseases and pest infestation.
When researching soil alternatives though, consider the needs of your plants, as they won’t all be the same. For example, tree bark and other woody materials retain moisture well. These particular materials benefit plants that like a lot of water. Perlite, vermiculite, coarse sand, and calcined clay are great alternatives for plants that don’t like soggy roots.
Temperature and Shelter
A plant’s temperature and shelter requirements will differ depending on its type and where it’s native to. Tropicals typically won’t tolerate temperatures below 40°F. Some shade perennials can withstand -40°F in dormancy but start to wither in anything above 75°F.
If you’re growing tender perennials, planting them underneath a larger plant or tree will provide natural protection from wind, rain, and intense sunlight. Permanent structures like pergolas and arbors work well for this, too.
With outdoor weather not being as much of an issue, indoor houseplants normally prefer a temperature range of 60 – 75°F (15 – 24°C). Some require more light than others and some will be more sensitive to the dry air of winter. In which case, daily spritzing may be needed to maintain adequate humidity.
Summary: What Does A Plant Need To Survive?
With air, sunlight, water, and space a plant will grow and survive oftentimes in the most surprising and intolerable circumstances. However, for plant life to thrive the addition of the optimum environmental conditions such as soil pH, nutrients, temperature, humidity, and hours of light all play a vital role in sustaining a plant through to the flowering snd reproduction cycle.
