Why Spruce Trees Need More Sun Than Shade (Growing Tips)
Spruce trees are an all-season favorite, whether you have just one in your yard, or you’re growing a landscape full of spruces. Of course, these trees need the proper conditions to really thrive. And thus, we come to the question of their sunlight requirements.
Simply put, it’s best to give spruce trees full sun. That means at least six hours of unimpeded sunlight. While the specific light requirements may vary with the type of spruce tree, this rule applies to any variety. Make sure to plant new spruce trees in open areas free of significant shade covering.
We all know that it isn’t as simple as just six hours a day, however. There are certainly other factors that can affect how much sun and how much shade your spruce tree needs. In this guide, we’ll go over why spruce trees need a certain amount of light, how to tell when they need shade, and moreover, how to keep your spruce trees growing strong!
Yes, Spruce Trees Prefer Full Sun Instead Of Shade
In general, spruce trees do best when they have full sun. Full sun means that they get at least 6 hours of unimpeded sunlight every day. Sure, they might survive in other conditions, but if you’re looking for optimal placement, make sure you plant them in a bright, sunny area.
Having a tree is an investment. While it entails some amount of financial investment, it really comes down to investing your time and labor. Although time-consuming, the payoff you get is a happy and healthy tree that enhances the look of your landscape.
There are plenty of reasons that spruce trees prefer full sun, and they’re much the same as many other evergreens. Of course, we’ll delve into these reasons as we progress further in this guide.
Spruce Trees Can Sometimes Handle Partial Sun
Now, we do have to say that if you’ve planted your spruce trees in an area that doesn’t get full sun, don’t panic. Your spruce tree might be okay, even if it’s only receiving partial sun.
Remember, spruce trees prefer full sun. Not only that, a daily dose of full sun helps them thrive and reach their full potential. Some spruces don’t do as well in partial sun as others, although many can at least tolerate it.
If you’re not sure whether your variety of spruce can handle it, make sure you look up the requirements of the tree in question just to be sure.
But What If Your Spruce Tree’s Not Getting Enough Sun?
Unfortunately, uprooting your tree and replanting it elsewhere isn’t usually an option, especially if it’s already established itself.
Once a spruce tree is established, the roots can go much deeper than you might expect. Of course, uprooting the tree could do more damage than good.
If there are certain obstacles you notice that really cut into your tree’s light (such as decorations, a shed, fencing), it may be possible to relocate them. If the issue is other plants blocking the light, assess whether or not you can prune them back to allow better light access for your tree.
Why Do Spruce Trees Need So Much Sun?
Now to the question of exactly why spruce trees need full sun? We’ll go into details for each of the reasons further, but each reason is equally as important as the next.
First, spruce trees are not deciduous. Deciduous trees lose their leaves and regrow them in the spring. They have to have the energy to keep their needles alive and to continue growing.
Certain varieties of spruce, such as blue spruces, use the sun to keep their color vibrant. In addition, proper sunlight can help prevent illness.
They Need Sun To Keep Their Needles All Year
As we mentioned, spruce trees keep their needles all year round – they can’t take a break from supplying energy to their needles.
Spruce trees don’t have the same ‘hibernation’ period as deciduous trees. In order to keep their needles healthy and intact, they have to be able to photosynthesize. Keeping their needles offers them certain advantages, but they can’t do it without enough sunlight to sustain their current growth.
Plants create energy through photosynthesis, which requires sunlight to allow them to convert water and nutrients into usable ‘food.’
Trees that lose their leaves in the winter don’t need much sunlight to maintain themselves, because they’re not supporting leaves.
They Need Sun To Support New Growth
While you may not notice it, spruce trees do continue their growth throughout the year. Of course, you won’t be seeing major growth spurts in your tree through the winter, like you might in spring and summer.
However, the fact remains that these trees are continuously growing. So, not only do they need plenty of sunlight to keep their existing needles healthy, but they also need to be able to support new growth- no matter what time of year it is.
What To Do If You Notice Stunted Spruce Growth
If you’re noticing stunted growth, take a look at your tree and make sure it’s getting enough sunlight. While spruce trees have different growth rates depending on their variety, it’s still fairly predictable.
Spruce trees should grow at least six inches to eleven inches per year as a minimum, although many can grow as much as one to two feet annually.
If your tree isn’t reaching the minimum growth expected, it could be an issue of not getting enough sunlight. If it is, make sure you check for proper watering and fertilizing before you look at other possible health issues.
For information check out our article on how to water your spruce tree to make sure you’re giving your spruce tree enough water at the proper intervals.
Blue Spruces Need Sun To Retain Their Color
Blue spruces are one of the types of spruce we mentioned earlier. While they also need sunlight to continue growing and maintain their current needles, they also need full sun to maintain their signature color.
Blue spruces are prized for their color, but they need the right ingredients to achieve it.
While there are plenty of things you can do to increase the intensity of your tree’s color, full sun is the one thing that they need most of all. Again, this comes down to their need to photosynthesize.
The more your tree can photosynthesize, the more it can produce pigments that give the tree its famous color. Here’s our piece on how to make your blue spruce more blue if you have a specific blue tinted variety!
Other Things To Do To Keep Your Blue Spruce, Blue!
- Ensuring your tree is getting proper nutrients
- Using solutions specifically designed to enhance blue coloring
- Making sure your soil is nutrient-dense and drains well
- Ensuring your blue spruce gets enough water
If you’re looking for a good fertilizer that will help your blue spruce achieve its best color, try the Espoma Organic Evergreen Tone fertilizer. It has a 4-3-4 composition, and it’s a reliable formula for all spruce varieties, although it’s especially helpful for blue spruces that need a boost to their color.
Fertilizing will often help a blue spruce that ISN’T blue enough as well. Mostly, this is because some lack of water, nutrients, combination of the both, or an external issue from some fungi.
Sun Can Prevent Mold Or Fungus Growth On Spruce Trees
One thing most people don’t think about when they consider spruce tree light requirements is fungus and mold. Sure, they’re not something we want to think about, but still, it’s a necessary topic.
Spruce trees, like other evergreens, tend to be susceptible to fungus and mold. This is especially true when they’re in wet, warm, or humid climates. These are the ideal conditions for fungus and mold to take hold.
And because spruce trees tend to have densely packed needles that stay on throughout the year, it gives these microbes ideal spaces to build colonies. If left untreated, they can cause major health issues that spread throughout the entire tree.
Sunlight Dries Any Moisture Throughout The Tree
Sunlight serves a couple major functions when it comes to preventing mold and fungus growth. It helps dry wetness throughout the tree, which makes it more difficult for mold and fungus to grow on the tree.
The way sunlight helps with mold or fungus is through its ultraviolet rays. These rays actually kill many types of mold and fungi, which can not only prevent them, it can also eliminate them.
That’s right. Sure, it might sound too easy. Thankfully, this is one tip that is not only tried and true, but is backed by science.
What Else Do Spruce Trees Need Besides Sunlight?
Now you know why full sun is so important for your spruce tree’s health and growth. But what else can you do to ensure that your spruce tree lives a long and healthy life?
There’s good news: we’re also going to review the other things spruce trees need.
Aside from getting at least six full hours of sunlight each day, one of the most important things for your tree’s health is the soil surrounding it.
And believe us, the soil is a little more complex than you might think. You need to look at things like moisture levels, soil composition, and the nutrients within that soil.
If you’re thinking of planting a new spruce tree, take a peak at our list of the top spruce trees to plant!
Spruce Trees Need Moist Soil
Spruce trees need to photosynthesize almost constantly to continue their growth. But, they can’t do this by means of sunlight alone. They need nutrients, and most of all, water to allow this process to take place.
Keeping up with watering your spruce trees can be time-consuming if you do it by hand. That’s why most people prefer to set up an irrigation system around their trees. Whether it’s a simple sprinkler system or a more complex in-ground system, it’ll help you keep your trees healthy.
As seen in a study published by Agricultural and Forest Meteorology, spruce trees have less sap flow when they experience drought-like conditions. Sap flow is important for trees to heal abrasions or damage from pests, and protect themselves from further damage.
Note: if you use a sprinkler type of system, be careful that too much of the water isn’t sprayed onto your tree’s needles. If left unchecked, it can invite mold and fungi.
Spruce Trees Need To Be Fertilized
Photosynthesis requires three main ingredients (besides the plant, of course): sunlight, water, and nutrients. While most soil naturally contains some amount of nutrients, you’ll probably need to add fertilizer to your spruce tree’s soil.
The fertilize you should use for your spruce trees is different to the kind you’ll use for your other garden plants. With that said, even an all purpose fertilizer is better than adding no fertilizer at all.
Spruce Trees Need A Lot Of Nitrogen
Spruce trees have different needs than, say, a daisy or geranium. They especially need more nitrogen. Nitrogen promotes new growth, and really benefits the ‘green’ parts of a plant. And, as spruce trees are evergreens, you can see how they need more of this nutrient. They also need more phosphorus, which also promotes growth.
In an article from Tree Physiology, it states that nitrogen allows spruce trees to properly release excess moisture (which in turn, allows them to take up new moisture, and the nutrients that come with it).
NPK Formula – What Does It Mean?
You can look at a fertilizer’s NPK formula to see the ratio of each of the main nutrients within. On the package of each fertilizer, you’ll see a number in a format like this 10-6-4. The first number is for N (nitrogen). The second number shows P (phosphorus). And last, the third number means K (potassium).
There are special fertilizers designed to meet the needs of spruce trees and other evergreens. You can make sure they contain a good ratio of nitrogen by looking at the NPK listed.
Here’s our list of best spruce tree fertilizers if you’d like to go down the rabbit hole there.
When Should You Fertilize Spruce Trees?
You can plan to fertilize your spruce trees either once or twice a year, depending on the indications listed on your fertilizer. So, you’ll either add fertilizer once in the spring, or, twice, with one application in spring, and the other in early autumn.
According to research published in Tree Physiology, the overall health was much greater in the needles of the Norway spruce trees when they were fertilized, versus the control in the experiments, which were unfertilized Norway Spruces.
Spruce Trees Need Well-Drained Soil
It’s good to keep your spruce trees well hydrated, but it’s not good to keep their roots soaking in excess water. That might be a little confusing. You just read that you need to keep the soil moist, right? Spruce trees like damp soil- not soaked soil.
To achieve this, you need to make sure your soil drains well.
You should be able to give your tree a thorough, deep watering, and come back in minutes without finding water standing on the upper levels of the soil.
Use A Meter To Check Your Soil
Some growers inspect their soil visually, or even feel the soil to assess the level of moisture remaining throughout the day as the water drains away.
If you’re not experienced in this, or you just want to make sure you’re getting it right, buy a meter like this SONKIR Soil 3-in-1 Meter. It can show you the moisture levels in your soil, detect the pH (because spruce trees like slightly acidic soil this is a big bonus), and even assess the light that gets to that area.
If you’ve noticed that the soil doesn’t seem to drain very well, and you haven’t planted a spruce tree yet, you can plant it somewhere that has a natural incline to facilitate drainage.
Make sure as well not to grow certain plants under a spruce tree
Spruce Trees Should Be Mulched
Perhaps you have soil that drains too quickly, or perhaps you don’t want to spend as much time watering. Or, maybe you’d like to add a little extra natural fertilizer to the soil around your tree.
No matter which it is, the solution is the same: mulching spruce trees is beneficial for the tree, and convenient for you.
Mulch Insulates Your Soil
The basic purpose of mulch is to insulate the soil. By that token, it also helps maintain the moisture in the soil.
Being able to count on a steady level of moisture in the soil means you won’t have to worry as much about your tree drying out and becoming dehydrated.
Another reason to use mulch is that it insulates the soil during the winter, and can help keep a more even temperature in the root zone.
Essentially, that also means that even though the ground above may be frozen, the soil beneath will be able to get moisture to roots more easily.
If you’re wondering, yes, it’s still important to water your spruce tree during the winter. Just make sure there isn’t a snow pile or ice on the ground, and that the ambient temperature is at least 40 degrees Fahrenheit.
How Should I Mulch My Spruce Tree?
Mulch about two or three inches deep, using organic material like pine needles or shavings, or medium-coarse wood chips. The good thing about these materials is that they break down over time, and naturally add nutrients to the soil.
Also, you can really get these at any local gardening store!
You can also use compost as mulch for your spruce trees, and as a bonus, it’s also rich in nutrients. The other good thing about using compost as mulch is that it’s easy to make for yourself!
Your Spruce Tree May Need Pruning
Is pruning something that a spruce tree prefers? Maybe not. However, it is something your tree needs.
Pruning serves many purposes, including: maintaining the appearance, preventing damage among branches, reducing the likelihood of pests and disease, and removing damaged branches.
Not only that, annual pruning also allows your tree to make the most of the sunlight available to it. The result is that the remaining branches can get the most out of the sunlight that reaches them.
How To Prune Damaged Spruce Branches
So if you’re not sure if your tree is getting a full six hours of sunlight each day, pruning can be another way to help your tree better use the light it does get.
If you notice obviously damaged limbs or branches, trim them to around ⅓ of their length, unless the damage extends further.
Basically, that means that when you cut the affected branch, you should cut back far enough to just reach the healthy wood of the trunk or leading branch. However, we always recommend contacting a professional if you are unsure how to do this.
Now if your spruce tree is TOO damaged (many branches have damage) then you may need to cut down your spruce tree.
A Quick Recap!
So now, we’ve covered our main question: do spruce trees need sun or shade? The fact is spruce trees do best with full sun. Which means at least six hours of unfiltered sun each day. Some spruce trees can tolerate partial sun, but if it’s possible, it’s much better to give your spruce tree full sun.
So, what does sunlight do for a spruce tree?
- Adequate sunlight helps spruce trees create enough energy to maintain their needles, and continue new growth throughout the year.
- Sun helps certain species of spruces maintain a more vibrant color
- Sun can help prevent problems with fungus and mold.
Good luck on your spruce Tree Journey!
Lagergren, F., & Lindroth, A. (2002). Transpiration response to soil moisture in pine and spruce trees in Sweden. Agricultural and forest meteorology, 112(2), 67-85.
Stenberg, P., Linder, S., & Smolander, H. (1995). Variation in the ratio of shoot silhouette area to needle area in fertilized and unfertilized Norway spruce trees. Tree Physiology, 15(11), 705-712.
Stockfors, J. A. N., & Linder, S. (1998). Effect of nitrogen on the seasonal course of growth and maintenance respiration in stems of Norway spruce trees. Tree physiology, 18(3), 155-166.