So you’ve got a lovely shady spot under a pine tree or two, wondering if Hostas will do well. Yes, they will, if you know what you’re doing.
It’s a myth that pine needles increase soil acidity, making them unsuitable for growing hostas under pine trees. The real challenge is the tree’s root distribution and their water and nutrition rights claim, competing with hosta plants under trees.
As mentioned in my article How to Grow Hostas Under Trees, there are some challenges to growing hostas under pine trees specifically. I, however, did mention that it is doable if you take the right measures, so let’s explore what those measures are.
Will Hostas Grow Under Pine Trees
Hostas can flourish in the shade of pine trees, but let’s review the basic needs of the Hosta species of the Asparagaceae (asparagus) family. Hostas are herbaceous perennials that may withstand temperatures as low as Zone 3, depending on the type.
Hostas, sometimes known as plantain lilies, have fleshy roots and short-spreading rhizomes. Broad leaves sprout from a central crown in the spring and produce a mounded structure, which helps cover the soil and limit weed growth by providing shade while providing delightful texture and color to gardens.
Hostas’ two essential requirements are their need to be kept out of the midday sun, and their soil needs to be well-drained and organically rich. If the soil is prepared with enough organic matter before planting, Hostas can thrive in the shade of pine trees.
To answer the question, can hostas and pine trees coexist? The answer is; absolutely. Let’s look at the challenges this presents and the ways you can overcome them to create an exquisite feature in your garden.
Growing Hostas Under Pine Trees – Problems and Solutions
What is unique about the environment under these trees that may present a challenge to establishing a lush hosta bed? Let’s review the challenges pine trees present to growing hostas and then see what we can do about it.
What About Acidic Soil
It’s a myth that the pine needles create acidic soil or that adding pine needles to a bed can lower that soil’s pH, and it’s even untrue that pine trees prefer naturally slightly acidic soil.
According to NDSU, the Ponderosa Pine (Pinus ponderosa) tolerates alkaline and even saline soils, but prefers a pH of between 6.0 to 8.0, which is quite neutral.
Interestingly, pine trees require exactly what hostas require: well-drained soil. They, too, cannot tolerate flooding or poorly drained soil, so snap for hostas and pine trees.
According to the University of Florida’s IFAS site, the Scotch Pine (P. sylvestris) prefers soils with a pH of 7.5, so it also prefers basic soil.
Shade for Hostas Under Pine Trees
While all pine trees do not tolerate shade, they provide the shade that hostas require. Ideally, your hosta plants want 3 to 4 hours of sunlight a day, which should be in the morning or evening—another tick for the two to live symbiotically together. Hostas and pines can be friends.
Root Structure – The Battle of the Roots
A limiting factor in planting hostas with the genus Pinus is finding space in the shallow network of roots.
If there is a dense network of roots from several pines or other surrounding trees, growing the larger hosta varieties may be difficult, and you will have to plant smaller varieties instead.
You may be considering using an axe to tactically chop some tree roots to accommodate the planting area of a hosta.
I would advise against it unless you’re prepared to potentially sacrifice your pine for a hosta patch. Yes, removing some small feed roots is not a problem, just don’t get carried away.
Water and Nutrition Competition Under Trees
The more roots there are in the planting area, the more the hostas have to compete with the pines for moisture and nutrients. There are ways to ease the challenge, so having looked at challenges, let’s focus on solutions.
Growing Hostas Under Trees – Solutions
When you get a chance, please look at my article on growing hostas around trees for information on growing hostas under large trees (see link below).
In that article, I said that the thicker canopy of this tree would also block a large majority of the water and sun, and you could also easily damage the tree’s root system when you plant your hostas under trees.
I also give a step-by-step guide on how to plant hostas under trees. Regarding planting under pines, the following advice could be a game-changer.
Tips for Dealing with Tree Roots
The main purpose of this project is to preserve the tree roots while allowing your hostas to extend their roots. To do so, I’ve discovered that picking out hostas in small containers or plants with bare roots is the greatest option.
You’ll be able to go closer to the trunk(but not more than 12-inches) without digging a huge hole and damaging the roots. Get a trowel and dig a shallow hole only big enough for your hosta’s root ball or roots.
If you come across a little larger root, relocating your hosta is preferable to avoid future problems.
You should also avoid injuring the bark at the base of your tree, and if you do, you risk inviting pests and illnesses that could infect the tree, which might eventually kill it.
Soil Amendments – A Key to Success
From my experience, most hosta species are tough and hardy plants. However, you’ll want to test and amend your soil before planting your hostas to ensure they have the best chance of establishing and flourishing.
You can achieve optimal water management capacities by adding compost to your soil, not only in the hole you dig for your hosta root ball.
Adding a layer of between 2 to 4 inches of quality compost across the entire area, which you intend to plant two weeks before planting, helps the compost stabilize in its new environment.
This will boost the diversity of your soil’s microbial life (soil biota) and improve the soil’s water (and nutrient) management capacity.
A Guide for Watering Hostas Growing Under Pine Trees
Sorry, but I need to inject some mathematics. A gallon comprises 231 cubic inches, and a square foot is 144 square inches.
If we wanted to water our plants an inch a week, a gallon (231 cubic inches) would cover 1.6 square feet (231/144). Put differently, covering a square foot of soil with an inch of water would require 144 cubic inches, or 0.6233 gallons (144/231).
Watering 100 square feet of water an inch a week would require 62.33 gallons (0.6233 x 100).
Drip Watering and Feeding Hosta Plants under Pine Trees
An application of 60 to 90 gallons of water per 100 square feet will provide your hostas with enough water to excel (an inch to an inch and a half). Because the hostas and trees compete for moisture, keep a close eye on these moisture levels.
A drip irrigation system is a fantastic option. I especially like it as it allows you to irrigate the root ball directly (and even add the occasional fertilizer) without over-watering the tree.
Evaporation and Weed Control With Mulches
It is important that you add a two-inch layer of mulch around your new hostas. Mulch will help keep weeds out, and it also helps the soil retain moisture each time you water. While the pine needles offer some mulching, I would add a thin layer of coffee grounds covered with shredded leaves.
Compost and mulch are different and are used for different purposes. Yes, they are closely related, and it is sometimes confusing.
Compost directly feeds and improves the soil, quickly becoming part of the soil structure.
Mulch is usually a courser covering that is used with the intended purpose of reducing the loss of soil moister as well as reducing the germination of weeds. Eventually organic mulch breaks down and feeds the soil.
Boosting Nutrition for Hostas Under Competition
Fertilizer is a necessary when growing hostas under trees because the hosta will be vying for resources with the much larger tree.
Fertilizer is required to get the hosta’s best size, shape, and glossy sheen to the luxuriant leaves, especially with the larger cultivars.
While hostas are not heavy feeders demanding of Nitrogen (N), Phosphorous (P), and Potassium (K), in this case, planted around trees, they’re competing for food.
A balanced plant fertilizer is perfect for replenishing these nutrients, along with the trace elements that contribute to the health of hostas.
Do not apply any fertilizer after August, as it will stimulate new growth when the hostas need to prepare for winter dormancy.
My article, How to Use Hosta Fertilizer to Keep Your Hostas Beautiful reveals all you need to know about hosta fertilizing needs.
Will Hostas Grow In Tree Roots
Some tree roots use chemical defense mechanisms to defend themselves from plants wanting to compete for limited resources, a trait called allelopathy.
Some Cedar trees are notorious for this. Other trees welcome the additional life as it boosts soil microbial life that benefits them too.
How Long Does it Take Hostas to Spread
Most hostas increase in size by producing tight growing rhizomes that form clumps. A few hostas grow with extended rhizomes, allowing them to fill in areas more quickly. These are mostly small growing hostas.
Our article Do Hostas Spread or What are Spreading Hostas? will answer questions you may have.
Are Hosta Roots Invasive
No, they’re not. While seeding can produce an increase in your garden, hosta rhizomes are not aggressive reproducers, unlike mint, for instance.
As mentioned above, you will get tons of information in our How to Grow Hostas Under Trees article. In that article, I was skeptical about growing hostas under pine trees, but with the care tips provided above, I believe it is quite possible to succeed.
The primary concern is to secure a fighting chance for your hostas to get fair access to water and nutrients. Drip watering and feeding is an excellent choice, allowing you to save on water and nutrition costs, possibly enough to validate the expense of the system.