The need for plants that exhibit rapid growth is a common factor in gardening and landscaping decisions, whether the goal is to establish a quick visual barrier, produce a fast harvest, or simply fill an empty space. Plant species vary dramatically in their inherent growth speed, with some adding multiple feet of height in a single season while others measure progress in inches. Understanding the factors that drive this speed, along with knowing which specific plants to choose, allows for the creation of a dynamic and quickly satisfying outdoor space. Selecting the right fast-growing plant balances the need for speed with long-term suitability for the site.
The Biological Mechanisms of Rapid Growth
The speed at which a plant accumulates biomass is fundamentally determined by its biological machinery and genetic programming. A major differentiator in growth rate is the method of photosynthesis used to convert light energy into sugars. Most plants use C3 photosynthesis, where the initial carbon compound formed contains three carbon atoms. While efficient in cooler climates, the primary enzyme, Rubisco, can mistakenly bind to oxygen instead of carbon dioxide, a wasteful process called photorespiration that slows growth.
Certain plants have evolved C4 photosynthesis, a mechanism that concentrates carbon dioxide around Rubisco. This adaptation minimizes photorespiration, allowing the plant to fix carbon more efficiently, especially in high light and high-temperature environments. C4 plants, such as corn and sugarcane, often exhibit superior growth rates and better water-use efficiency in warm conditions. Genetics also dictate growth habit, with some plants prioritizing vertical elongation and leaf production over dense root systems, leading to accelerated visual growth but sometimes shorter lifespans.
Fastest Annuals for Immediate Impact
Annual plants are defined by a life cycle that completes within a single growing season, making them the default choice for immediate, temporary impact. Many annual vegetables offer the fastest gratification, with radishes ready for harvest in as little as three to four weeks. Leafy greens like loose-leaf lettuce can be harvested consistently within 40 to 50 days of sowing.
For vibrant color, flowers such as zinnias and cosmos are prized for their speed, frequently blooming within 60 to 90 days after planting. Zinnias are resilient and produce abundant flowers, making them a popular choice for cut flower gardens. Sunflowers are excellent for a quick, tall screen, and dwarf varieties can reach maturity and flower in under 60 days.
Nasturtiums are another versatile annual, providing rapid ground cover, edible leaves, and flowers, often sprouting quickly from large seeds. They require minimal fuss and perform well even in poorer soil conditions. This category of plants is ideal for filling gaps, adding seasonal color, or creating a fast, temporary visual barrier.
Quick Growing Shrubs and Hedges
For structural, long-term privacy, quick-growing shrubs and hedges establish permanent boundaries and screens. Plants in this category are defined as fast-growing if they add 40 to 60 centimeters (about 1.3 to 2 feet) or more of height each year. The Leyland Cypress (Cupressocyparis leylandii) is famously one of the fastest hedging plants, capable of growing up to 91.5 centimeters (three feet) annually.
While the Leyland Cypress offers unmatched speed, it requires consistent pruning to manage its size and dense growth. Other reliable options include the Cherry Laurel (Prunus laurocerasus), which adds 40 to 60 centimeters per year and maintains glossy, evergreen foliage. The common Privet (Ligustrum ovalifolium) is another fast-growing choice, reaching up to 60 centimeters of growth annually and responding well to shaping.
For an alternative to traditional hedges, certain vines can be trained on a trellis or fence for rapid coverage. Fast-growing climbers like the trumpet vine (Campsis radicans) or various honeysuckle species quickly cover large vertical areas. Maintaining these quick-growing woody plants requires regular, often semi-annual, pruning to direct their rapid growth and maintain the desired shape and density.
Trees That Provide Fast Shade and Structure
Trees selected for rapid growth are sought for their ability to deliver quick shade and establish a landscape’s vertical dimension sooner. Fast-growing trees generally exceed 24 inches of annual growth, with the most vigorous species adding up to 5 to 8 feet in a year under ideal conditions. Hybrid Poplars (Populus x canadensis) are among the most rapid growers, maximizing hybrid vigor to achieve quick height.
The Silver Maple (Acer saccharinum) is another rapid grower, valued for its distinctive silvery-grey leaf undersides and ability to establish a large canopy quickly. The trade-off for this speed is often a softer, weaker wood structure, making these trees more susceptible to branch breakage during storms. Many fast-growing species also have shorter lifespans, averaging 30 to 60 years, compared to slower-growing hardwoods.
Aggressive root systems are another common characteristic, especially in species like willows and silver maples, which can infiltrate water sources like sewer lines. Planting fast-growing trees requires careful consideration of their mature size and location, ensuring they are placed far from structures and underground utilities. The American Sycamore (Platanus occidentalis) and the Red Maple (Acer rubrum) offer better structural integrity while still providing a relatively fast growth rate.