Weeds are a problem when they grow under pine trees. Pine trees have shallow roots, which makes them more susceptible to competition from weeds. Further, the needle-like leaves create an acidic environment that does not support the growth of other plants. Weeds such as stinging nettles (Urtica dioica), couch grass (Elytrigia repens), and brambles (Rubus spp.) can appear under your pine trees. They become caught up in the roots, making them difficult to eradicate. They will compete for nutrients with your pine trees, and therefore you must control them. Take the following steps to remove them:
Uproot by hand or using tillers
You can remove weeds under your pine trees by uprooting them. This can be done by hand or using a tiller. The goal is to eliminate the entire plant, including the roots, to ensure they do not reappear again.
Uprooting weeds by hand is more time-consuming than tilling. You have to identify the unwanted plants, pick them out and dig around the trees to ensure you have gotten rid of the roots and stem cuttings that might propagate new weeds.
Avoid disturbing the soil too much when using a hoe or tiller to remove weeds, as it might encourage weed growth.
Chemical herbicides can kill weeds under pine trees. However, you must ensure that the herbicides do not impact the trees. Avoid applying broadleaf weed killers or herbicides that attack the roots, such as Atrazine.
Purchase weed killers that spare trees and shrubs. The best herbicides should kill weed seeds as they emerge from the ground. Roundup is the best option to kill weeds, but it should be used without any surfactant (agents used to improve the spread and wetness of herbicides).
If you spray weed killers, do so on a windless day to avoid affecting nearby trees and bushes. You can also limit the risk to your trees by using a brush dipped in weed killer instead of a sprayer. This gives you more control over the spread of the chemicals and protects the plants.
The use of chemicals is highly discouraged around pine trees because of the potential harm. Some substances are also difficult to apply appropriately. Cultivation is the best option for removing weeds from the base of your pine trees.
Mulching and planting groundcover are effective deterrents against weed growth. Mulching can be done when your pine trees are young and mature. Groundcover crops should be planted when the trees are mature and have better-established root systems.
You can use bark and fallen pine needles to create mulch. Pine needles are acidic and discourage the growth of weeds. Mulch also returns nutrients to the soil. Organic mulches will decompose over time, so you must reapply at least once per year.
Spread the mulch a few inches thick and ensure that it does not touch the stem of your pine trees. Ideally, mulch should be kept around 6-12 inches from the trunk. Mulch conserves moisture in the soil, which might create conditions for pests and diseases that will affect the tree.
Choose grass cuttings as an alternative for your mulch only if you are sure they are weed-free. Allow the cuttings to wilt first to deter snails.
Fabric mulches last longer, but they are considered unattractive by most farmers. Further, they do not add to the soil quality like organic mulches. Use layers of newspaper, weighed down with soil or grass clippings to mulch under your pine trees.
Alternatively, you can purchase a black plastic sheet and cover the ground around your trees. This is called solarization and is a sure way of suppressing the germination of weeds over a long period.
Fabric mulch is more effective in controlling weeds over a longer period compared to organic mulches as it eradicates all plant growth under it. Organic mulches might facilitate the germination of weeds if left on the ground for too long.
Plant ground cover beneath your palm trees. Groundcover plants spread around the base of the trees and block out light from reaching weeds, thus suppressing their germination.
This should be done only for trees that are a few years old. Research the best shade-loving ground cover plants that thrive in your region. Plants such as spotted deadnettle (Lamium), moneywort (Lysmachia), ferns, and wild ginger are shade-loving and good options for weed control. Additionally, plant groundcover that flourishes in acidic soil.
There are different ways to control the weeds growing under your pine trees. Mulching, tilling, and groundcover plants are the most effective ways to remove and control weeds. Chemical herbicides work, but they should be avoided due to the potential harm to your pine trees. Weeds will compete with your pine trees for nutrients, so it is best to eradicate them early.
The process is similar to getting rid of weeds in Asian jasmine.