Fighting Crabgrass Around Citrus Trees & Other Fruit Trees
Many of our young citrus trees have been growing terribly slowly over the past few years. After fertilizing, nursing iron deficiencies, and constantly getting rid of aphids, mealy bugs and scale, the trees are still runts. The cause, we realized, is the huge matrix of weeds strangling the roots: Crabgrass.
Crabgrass…it’s everywhere on our property and it’s a constant battle. We refuse to concede to herbicides, or worse yet, forfeit our win to Roundup. With brawns, brains, and grit, we’ve been fighting the organic way, and I think it’s finally paying off!
Since we’re probably not the only ones on the frontlines against sinister garden and orchard weeds, I’m sharing our battle strategy.
Planting a fruit tree amongst weeds (the preventative method):
Dig, dig, dig. Yep, manual labor. We have a rototiller, but honestly, the best way to get a nice, as weed-free as possible hole for your young tree is to dig out a hole with a shovel. To make digging a little less daunting, dig a small crater, fill it with water and let it soak into the earth. Do this a few times and wait a few hours. Or, wait to dig until after a heavy rain. Once the area is saturated, started digging. Dig out the dirt, weeds and all, deep enough to the level of the soil your tree is potted in. The diameter of your hole should extend around the circumference of the span of your tree’s branches. For example, most of our young trees from 5-gallon pots have holes with a radius of about 19” from the trunk.
Before placing the tree in the hole, make sure the hole is clear of any weeds. Crabgrass is tricky because there is a network of roots like a circulatory system below ground. It’s important to pull these out as completely as possible, by the roots. Make sure the dirt going back into the hole is also weed-free.
Next, throw in a cup of organic fertilizer such as E.B. Stone Organics Citrus & Fruit Tree Food (7-3-3). Only use organic fertilizer when first planting fruit trees since it is slow releasing.
Carefully remove the tree from the pot, while hovering over the hole, by turning the tree gently and pressing on the sides of the pot, loosening the roots. The tree should slide out easily.
Place the tree in the center of the hole, making adjustments as needed and in fill in with dirt around the tree, near the potted dirt until it resembles a volcano.
Next, place the boarder around the tree. We use Terrace Board, 5in.x40ft., Brown Landscape Lawn Edging from Home Depot. Instead of staking the ring in place, we use a rivet gun and punch four rivets to attach the ends of the ring. Next, we position the ring and begin adding dirt along the inside and outside edges to keep it in place. On the outside, fill the dirt just so half of the boarder is sticking out. This will help keep the bark mulch from spilling out, and will act as a weed-whacking barrier on the outside.
Fill the inside of the ring with the dirt you dug out, sifting and throwing away the weeds. Fill the dirt about a third of the way up the boarder. Next, fill in the remaining area with bark nuggets. Don’t use fine mulch. Fine mulch will decompose swiftly and foster crabgrass growth. We use acorn bark (medium redwood nuggets) from BD White Top Soil Company, but you can also try medium sized nugget mulch from Home Depot. Your mound of bark nuggets should reach the top of the boarder, all the way to about an inch from the base of tree trunk. There should be a gap between the trunk and the mulch. The mound will look kind of like the top of a muffin.
Now, water. It’s important to water inside the ring, near the edge of the root span, rather than letting the water pour on the trunk, which can create fungus problems. Keep the hose low to the ground when watering, and water according to weather, soil, and tree-type. We usually water thoroughly once a week, and twice during the hot summer.
Keep on top of the crabgrass. Don’t let it grow tall around the border. Crabgrass can grow up and over borders, plop a set of roots down, and reek havoc. The bark nuggets will definitely help, but weed whacking is a good preventative. Crabgrass also creeps below and under boarders. Anytime you see a menacing blade above the nuggets, pull it out immediately, preferably, by the root.
Small, established trees:
We have a lot of trees we plopped in the ground before realizing what a potential disaster crabgrass is. So, while we dig around a couple of established trees at time, careful not to disturb roots, adding edging and nuggets, we use pavestones on other trees to begin the process of killing crabgrass.
To do this, pull away as much crabgrass as possible from the trunk of the tree, at least a foot in diameter worth. Then border the trunk with eight 12″x12″ pavestones. While these trees are waiting for edging and nuggets, the crabgrass underneath is being deprived of sun, therefore turning brown and dying. This will give the gardener the upper hand in fruit tree weed control.
We apply Tanglefoot around the base of all of our fruit tree trunks. Tanglefoot, certified by OMRI for organic use, is a naturally occurring gum resin that traps crawling insects that cause damage to trees. It’s very sticky and could cause damage to the trunk if not applied properly.
First, wrap the base of the tree using green vinyl garden tape, or something similar. Wrapping should only be about 2-3 inches thick. Apply Tanglefoot generously using a popsicle stick or brush around the tape only. Re-apply as needed.