Depending on which part of the country you’re living in, you may have found that pine needles dropped from mature pine trees can be detrimental to your garden.
Or perhaps you have been adding pine needle mulch to fertilize your garden with no apparent effective results.
The answer may be simple!
Pine Needle Acidity
Pine trees shed needles that can then create a layer of needles all around the trunk.
There is a myth that pine needles can change the pH of the soil under the trees and pine needles can become too acidic.
This myth perpetuates that the acidic soil can therefore kill off plants in the area around pine trees.
While pine needles are acidic, pine needles have a pH of 3.2 – 3.8, they will not have any effect on soil what nature provides and simply dropped from a nearby tree.
However, there is some truth in that pine needle mulch can have an adverse reaction to a plant that simply does not like pine needles.
Pine Needle Mulch
So, there’s a lot of gardeners that put pine needles down as mulch for their garden. Mulching in the garden helps to control weeds and is a great way to retain moisture in the soil. Mulches usually prevent slugs, snails, and other insects too.
Pine needles are usually a byproduct that is gathered in the fall and eventually used as mulch.
There is some discussion that pine needle mulch can slowly acidify the soil, and within 3-4 months, you may find your pH has dropped.
This effect is temporary but regular mulching with pine needles can yield consistent acidity. This is beneficial to acidophilic plants, which love to live in acidic soil (like petunias).
Just be careful; not all plants like pine needles!
Plants that Don’t Like Pine Needles
When it comes to which plants don’t like pine needles, here are eight plants that are not the pine needle mulch’s biggest fan!
1. Roses
A rose will grow well in many conditions:
- sunlight hours
- water
- air circulation
- humidity
- and the right soil pH
- Roses do not care for pine needles though.
If pine needles are going to be used as mulch, it might be the wrong choice for a rose garden.
If you want an organic mulch that is the best for your fragrant beauties, then you will want to look into sugar cane mulch, mushroom mulch, or compost.
Sugar cane has enzymes in it, which stimulate microorganisms in your soil to produce nutrients.
It’s also fast to break down and provides nutrients fast.
2. Asters
This big grouping of plants (they have many species) can vary in color, height, and garden potential.
There are fall and summer varieties, with flowers similar to daisies and colors of pink, white, red, blue, and purple.
Asters are usually quite easy to grow, unless the solid is clayey or dries out in the summer.
Ah, but one other thing can have a negative impact on the growth of these great flowers is pine needles.
Asters are not big fans of a lot of needles from pine trees.
So, you might want to skip the pine needle mulch or at least try to avoid growing them in a woody area, with a lot of pine needles, if you want the best of the best when it comes to asters.
3. Boxwood
Boxwood bushes are lush evergreen shrubs that are mostly enjoyed for their green foliage.
Frequently seen in formal garden borders, boxwood is relatively easy to grow.
Boxwood shrubs need soil that is ideally between 6.5-7 pH, which means almost neutral pH.
The best time to test the soil of your area is before you put in your boxwoods. Instead, you can test the soil after establishing your boxwood, if you don’t want to wait.
You will be able to make adjustments for the pH with mulches when the boxwood shrubs are established.
If you discover the soil is acidic, a measure of lime will raise it as required.
As mentioned – Pine needle mulches can lower the pH of soil. Therefore, in order to achieve the soil conditions for your boxwoods, stay away from pine needles. Your pricey new plants will thank you for it.
4. Thistles
Thistles are another prickly plant, and thistles don’t always do well with pine needles.
Despite being Scotland’s national flower, thistles are widely regarded as a pest in the United States.
In this way, there are not a lot of thistles in gardens, but thistles are interesting and valuable plants.
The seeds of thistles are a valuable food source for farmland and garden birds.
However, if you want to incorporate some of your Scottish heritage or just appreciate the look and beneficial elements of thistles in your garden, it is better not to use pine needles as ground cover.
5. Lavender
Lavender! So many types, such nice aromas!
Lavender plants are usually pretty easy to grow – they like it drier, and well-drained soil!
Pine needles help the soil hold moisture and thus hydrate the plants, which isn’t ideal for many types of lavender.
6. Artichokes
An artichoke is a large perennial plant that grows best around the Mediterranean.
They have a long history of uses from using the leaves as a source of antioxidants or cooking and eating the bulbs.
One thing they don’t seem to care too much for is pine needles or using pine needle mulch.
7. Euphorbias
This big group of plants has more than 2,000 different species!
Around 1,200 of these are succulents, with a variety of shapes and sizes. Euphorbias are relatively low maintenance.
They tend to thrive in well-drained soils.
So… Pine needles can cause problems since they can cause water retention which results in wetter soils.
8. Decorative Garlic
Decorative, or ornamental, garlic belongs to the Allium genus. The types of decorative garlic vary in colors and include:
- blue
- white
- yellow
- lilac
- burgundy
- dark purple
- and pink
The flowering portion lasts about a month.
As a decorative garlic plant, it behaves like most other types of onion plants that originated as a steppe plants where they are usually found growing on treeless slopes.
This suggests that decorative garlic requires plenty of sunshine for good growth, which is why they do not do well under the heavy foliage of pine trees.
Similarly, Decorative garlic dislikes acidic-type soils and more generally under a pine tree because typically, acidic soils come from pine needles dropping. It is also a good idea not to use a mulch of pine needles on decorative garlic too.
As a decorative garlic plant prefers slightly drier soils, this also suggests avoiding pine needles will help to keep the soil free draining.
Final Thoughts on What Plants Do Not Like Pine Needles
While plenty of plants do well with soil that has pine needles as a mulch at the soil’s surface, there are a few that are a bit more sensitive.
For instance, pine needles can help to retain moisture in soil, which isn’t something some plants like. Pine needles can also lower the pH of the soil. Many plants may not do too well if the soil is acidic.
If you plan on planting one of the eight plants above, be mindful of where you plant them and stay away from pine needle mulching to ensure that you will get the most out of your bushes and blooms.