Did you know that there are more than thirty species of linden trees in the world, but just four very suited to the Denver climate? Lindens are a popular choice for Colorado landscaping due to their ability to withstand subzero temperatures and alkaline soil conditions. Learn all about how to care for Linden trees so that they can thrive in your landscape.
What Types of Linden Trees Thrive In Denver?
If you’ve heard that Linden trees thrive in Colorado, that’s true. But not all varieties of Lindens are well suited to the front-range climate. The American or Basswood, the Littleleaf, the Redmond, and the Greenspire are the four species of Lindens that flourish in Denver’s alkaline soil and urban conditions. Learn how to identify each:
Also called the Basswood, the American Linden is sought after as a shade and statement tree. Easily recognizable with its unique flowers and large, heart-shaped leaves, this Linden species grows to 60 to 80 feet tall with a spread of one-half to two-thirds the height at a medium rate. When young, it has a pyramid shape that grows fuller and rounder with maturity.
The American Linden’s fragrant flowers are attractive to bees, making it linden a potential source of delicious honey. Interestingly, the course, dark green leaves are edible and are often fed to livestock.
A major benefit of this species is that it is highly adaptable. It can tolerate clay and a wide soil pH range. The American Linden grows best in full sun and well-drained soil.
This attractive Linden species produces vibrant yellow flowers that hang down on a long stalk attached to a leaf-like wing. Littleleaf Lindens bloom in late summer after most flowering trees have lost their blooms, and their nectar attracts bees and hummingbirds.
The Littleleaf Linden grows in an oval shape at a medium rate and will stand 50–60′ and a spread of around 40′ at maturity. It grows best in full sun or partial shade, and can flourish in acidic, alkaline, moist, rich, sandy, well-drained, wet, and clay soils. Another benefit of this species is that it transplants well.
Like many of the Linden varieties, the Redmond Linden also produces signature flowers starting in the spring and lasting until late summer. “Redmond” flowers are yellowish clusters that attract bees and butterflies. Taller than other Denver Lindens, the Redmond easily stands 75 feet at full maturity in a handsome full, pyramid shape. Its uniquely large leaves can grow up to 8 inches long!
The Redmond Linden grows well in full sun and somewhat drought resistant. It prefers moist, fertile soils and can thrive in warmer temperatures, unlike other Linden species. The Redmond makes an impressive lawn tree and is sought after by homeowners since it is resistant to most pests and diseases.
Looking for an attractive shade tree? The Greenspire is your best bet! This Linden species holds a tidy spire-like shape with dark green foliage throughout its lifetime. It shows off in the summer with beautiful yellow flowers and in autumn with a bold show of gold leaves.
Growing at a medium rate in full sunlight, the Greenspire Linden stands about 50 feet tall at maturity. It is ideal for homeowners looking for a low maintenance Linden variety because it is adaptable to both dry and moist locations, and is not preferential to soil type or pH.
Are Lindens Susceptible to Denver Pests?
When it comes to caring for Linden trees, one of the major factors involved is warding off pests. Every tree species has its weaknesses and the Linden is no exception. These are the top pests known to attack Denver Linden trees:
The Japanese Beetle
- These pests prey on over 300 species of plants and trees but they are particularly fond of Lindens.
- Japanese beetle adults chew flower blossoms and leaves, giving them a skeletonized look.
- Japanese beetles have a one year life cycle, emerging in full force from late June through early August. However, some adults may be found into September.
- They do not kill Linden trees, just render severe damage to their heart-shaped foliage.
- Japanese Beetle traps are ineffective for the Denver front range zone where the pests are well established.
- The most effective control measure is insecticide. It is important to select an insecticide that is not harmful to bees and other pollinators that benefit from Linden blossoms.
The Linden Aphid
- Aphids are tiny insects that secrete sap from Linden trees.
- If left unattended, they can seriously damage or even kill the tree. But with early detection, aphids can be controlled.
- Aphids are active during mild weather, usually in the spring.
- The pests leave a sticky honeydew residue on the leaves and bark of trees.
- If you see aphid eggs or residue hose down your plants to remove them.
- Insecticides can be used to control large aphid populations, but can also harm natural predators such as lacewings or lady beetles.
The Linden Borer
- This pest is part of the long horned beetle family.
- The American Linden is this beetle’s primary target.
- The borer tunnels underneath the bark and cuts off the flow of nutrients and water from roots and leaves.
- The borer can cause extensive damage and even death to trees.
- The pests are most active during the summer months from June through August and they overwinter within the wood the of tree to emerge the following spring.
- Bulges in the bark, reduced leaf size and a thinning tree canopy are early signs of an infestation.
- Broken limbs and trunks and dieback are advanced damage caused by the Linden borer.
- The most effective control methods include: trunk injections, sprays and insecticides applied to soil in spring and early summer.
How to Care For Your Linden Trees
If you are planning to add to your landscape and plant a new Linden tree there are special care steps to consider. Properly caring for newly planted trees during the first couple of years is critical to their development and ability to grow and prosper.
Caring For Newly Planted Linden Trees
Success begins with following planting best practices. Follow these suggestions from the Colorado State Forest Service to ensure that your tree is planted correctly:
- Plant the top of the root ball slightly above ground level. The root collar (flare) must be visible one inch above final grade.
- Set the root ball on solid ground and not on loose backfill in the hole; this will eliminate settling.
- Remove at least the top 1/2 of all wire and baskets from balled and burlapped trees and completely remove containers from containerized stock.
- Adding peat moss or manure to soil in the planting hole is not necessary. (Too much can cause a “potted tree” effect and restrict root growth.) Backfill hole with original soil.
- Do not fertilize at planting time.
- Optimum planting periods are from March 15 to June 15 and from September 1 to October 15.
Once planted, your next top priority is tree watering. Newly planted Linden trees are thirsty! They require more watering than established trees and are more susceptible to injury from drought, so it’s best to keep actively monitoring them and stick to a consistent watering routine.
Here are some Pro tips for watering your newly planted tree:
- Water deeply and slowly. Apply water so it moistens the critical root zone from near the trunk of the tree to the dripline to a depth of twelve inches.
- Try to maintain consistent soil moisture for better root water absorption.
- A newly planted tree should be watered every 3-5 days during the growing season, and newly planted trees need water during dry periods in the winter months as well.
- The “rule of thumb” for watering: apply 10 gallons of water per inch of tree diameter, for instance a 1 inch tree will require 10 gallons of water each time it is watered.
What is the best way to water a new tree? Methods for watering include a deep root fork or needle, soaker hose or soft spray wand. It’s best to apply water to many locations under the dripline. If a deep root fork or needle is used, insert the device no deeper than eight inches into the soil.
Caring For Established Linden Trees
Well established Linden trees may seem like they can take care of themselves, but fend off disease and pests they need regular care to be peak health. Watering and fertilization are the best ways to care for your established Linden trees.
The role of fertilizer is to act as a supplement, or vitamin, to trees and shrubs. Fertilizer is composed of minerals and nutrients that supply the ingredients required for successful photosynthesis and healthy growth. It plays an important role in balancing the Denver soil for Lindens.
Fertilizer is not a magic pill for trees that can cure all problems or diseases. Unadapted or unhealthy Linden trees that have been poorly planted or neglected for long stretches of time cannot simply be restored to full health with a cocktail of fertilizer. But when used strategically and correctly, fertilizer can help developing trees flourish, growing strong and healthy with care and attention.
Our skilled arborists can assess your Linden, to test the soil and check the growth rate, to determine an appropriate custom fertilizer package just for you.
The four Linden varieties that thrive in Denver are all susceptible to drought. Many people believe that drought is only a concern during the hot summer months, but that is actually incorrect. Trees can experience drought in winter too and watering during a plant’s dormant season is just as beneficial.
Root development occurs during dormancy and steady winter watering helps prevent dehydration and premature death in Linden trees. Although trees are dormant, they aren’t just sleeping all winter long. Linden trees are growing their root systems and they require added moisture to stay alive and thrive.
Schedule a consultation and team up with our certified arborists to create a custom care plan for your Denver Linden trees.