Tropical Gardening Helpline: Wood chips work to limit weed growth

  • Piling fresh wood chips for about six weeks before applying around the plants in your garden allows them to partially decompose and make better mulch. (Photo courtesy /
  • Fresh wood chips can be useful to reduce weed growth in garden pathways. (Courtesy /
  • The best use for fresh wood chips is to use them to block weeds in a pathway. (Courtesy /
  • Wood chips can be useful in gardens as long as they are applied when, where and how they can be most beneficial. (Courtesy /

Alex asks: We just took down a few trees that were blocking our view and had them chipped. We were going to use the chips as mulch in our garden. How thick should we apply it and does it require any special treatment?

Tropical Gardener answer: It’s always hard for me to hear about trees being cut down to improve a view. In a talk given by a dear friend several years ago, I heard him respond to someone who wanted to cut down trees for this purpose. “Maybe you should consider that the trees are your view?” he declared. This was spoken by a true tree hugger and I tend to agree.


Beautifying trees or thinning them so ocean vistas can peek through can actually enhance your view and make it more interesting. Think about this if you are considering removing more trees in your view plane in the future. Now, I’ll get off the soap box and advise you on how to use your wood chips.

The best use of fresh wood chips is to use them in pathways or wide areas where you want to limit weed growth. When applied at 3 to 4 inches deep, it can be quite effective at stifling weed growth. To increase the efficacy, you can spread newspaper, cardboard or weed cloth and layer the chips on top. As the chips break down they absorb and use nitrogen that they draw from the soil and the air. This helps slow any plant growth under them, including weeds.

Applying a thick layer of fresh chips directly to plants in your garden may not actually be that beneficial. They can rob your plants of a valuable nutrient in their decomposition process. If you are in a hurry and need to apply them now, be sure to sprinkle the chips with a high nitrogen fertilizer and water it in.

Topping the chips with blood meal, chicken manure or urea will help the chips break down while feeding the plants that are being deprived. You might want to do this several times, especially if you notice that the leaves of your plants are turning yellow. The watering will also somewhat reduce the heat that is generated in the decomposition process.

The best way to use the chips for garden mulch is to let them start the rotting process before applying. In our tropical climate and with a bit of nitrogen as a booster, the chips will be more plant friendly in six to eight weeks. If you maintain the chips in a pile, turning it often will also hasten the decaying process.

Once they are well on their way to decomposing, the chips will make good mulch. They will add beneficial microorganisms to the soil and the additional cover will stifle weed growth. To be an effective weed barrier, you’ll need to have the layer at least 3 inches deep. Be careful not to put the mulch right against the trunk of a tree or shrub as the heat of decomposition can actually burn your plants.

In Kona, where soil is a rather rare commodity, mulching with wood chips can be an excellent soil builder. Knowing how best to use your chips will likely help your garden’s health and appearance. Garden has a good article with photos at Check it out if you want more information.

Email plant questions to for answers by Certified Master Gardeners. Some questions will be chosen for inclusion in this column.

Diana Duff is a plant adviser, educator and consultant living in a dryland forest north of Kailua-Kona.

Gardening Events

Saturday: “Work Day at Amy Greenwell Garden” from 9 a.m. to 12:30 p.m. Meet at the Garden Visitor Center across from the Manago Hotel in Captain Cook. Volunteers will be able to help with garden maintenance and are invited to bring a brown bag lunch. Water and snacks provided. Call Peter at 323-3318 for more information.

Next Sunday: “Third Sunday Work Day” from 9 a.m. to 2 p.m. at Maona Community garden in Honaunau about a mile down the Puuhonua Road to the City of Refuge at 84-5097 Keala O Keawe Road. All are welcome. Potluck lunch will be served. For more information email or call Chantal at 937-9800.

Farmer Direct Markets

Wednesday: “Hooulu Farmers Market” 9 a.m. to 2 p.m. at Sheraton Kona Resort &Spa at Keauhou Bay.

“Orchid Diversity, part 2” starting at 6:30 p.m. at the Daifukuji Soto Mission Hall in Honalo on Highway 11 at mile marker 114, just north of Kainaliu with Thomas Mirenda continuing his September talk and including many miniatures. Potluck starts off the meeting. Guests are invited to participate. Call 328-8375 or visit for more information.

Saturday: “Keauhou Farmers Market” 8 a.m. to noon at Keauhou Shopping Center.

“Kamuela Farmer’s Market” from 7 a.m. to noon at Pukalani Stables.

“Waimea Town Market” from 7:30 a.m. to noon at the Parker School in central Waimea.

“Waimea Homestead Farmers Market” from 7 a.m. to noon at the Waimea Middle and Elementary School Playground.

Sunday: “Pure Kona Green Market” 9 a.m. to 2 p.m. at Amy Greenwell Garden in Captain Cook.

“Hamakua Harvest” 9 a.m. to 2 p.m. at Highway 19 and Mamane Street in Honokaa.

Plant Advice Lines


Tuesdays and Thursdays: 9 a.m. to noon at UH-CES in Kainaliu – 322-4893

Mondays and Fridays: 9 a.m. to noon at UH CES at Komohana in Hilo 981-5199 or

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