In the Garden: June

A weed is a plant growing where you don’t want it. Having an abundance of weeds is referred to as weed pressure, even if the weeds themselves are not harmful. I’m getting lots of questions about weeds right now, and people aren’t always happy with the answers.

The weeds people ask me about are unwelcome and opportunistic. They reproduce rapidly, crowding out other plants or messing up a carefully designed flowerbed. These weeds seem to come out of nowhere, their roots sneaking beneath the neighbor’s fence, or their seeds brought in by birds or a hearty breeze. Weed seeds are cunning and patient and remain viable for many years, waiting for the perfect conditions to grow.

People want to know how to get rid of weeds quickly, easily and inexpensively. They want something that’s safe to use around children and pets and pollinators. They want something natural, maybe something they can make themselves. And they don’t want to get dirty doing whatever it is that needs to be done because, well, who has time for that?

Weed control methods fall into three categories: mechanical, cultural, and chemical. Managing weeds usually requires a combination of methods used consistently over an extended period. This is especially true if you don’t want to use potentially dangerous herbicides – the chemical category method – though sometimes that’s the only way to get the results you want. I’m going to share a few research-based mechanical and cultural methods for successfully managing weed pressure in both new and established gardens and landscapes.

Mechanical methods of weed control are usually the first line of defense. Pulling weeds by hand is time-tested and effective, especially when combined with cultural methods. Mechanical weed removal can be started at any time, clearing as many weeds as possible,

Weeds are easiest to remove when the soil is damp, and the plants are young. Some weeds are shallow rooted, and others – like dandelions – have long deep tap roots that must be completely removed to keep the plant from growing back. Weeds that spread by runners or stolons are harder to eliminate by hand, as the entire root system must be dug and removed.

Tools for hand weeding are minimal: garden gloves, a hoe, and a hand trowel or Hori Hori knife for digging and removing tap roots. Shallow rooted plants can be hoed off at the soil level, leaving the roots in the soil. Small weeds can be pulled by hand: I keep a bucket in the garden and spend 10 minutes or so weeding each day. I find it peaceful and relaxing.

Cultural methods are things you can do to make your property less inviting to weeds. An extreme example would be paving your entire yard. A less drastic approach is choosing growing practices that make it harder for weeds to establish themselves. These include covering bare soil with mulch to deprive seeds of the sunlight they need to grow, and minimizing disturbing the soil – raking, digging, and turning – which brings weed seeds to the surface.

Placing plants closer together in your beds is a simple way to cover and shade the soil. Adopting watering practices that deliver water only where it’s needed – to individual plants rather than the entire planting area – is very effective. This can be done with a drip irrigation system or by hand watering at the soil level.

A time- and money-saving tip is to limit or eliminate the routine use of fertilizers on your lawn and in your growing areas, and to only apply them when truly necessary. Fertilizers contain high levels of nitrogen and other ingredients that make your plants greener and stimulate leafy growth. Why feed the weeds?

Mulching paths and unpaved walkways with a four- to six-inch-thick layer of bark or gravel can significantly reduce weed pressure. Landscape cloth is often recommended as a barrier to place beneath mulches, but its long-term effectiveness is no better than mulch alone. Some seeds will inevitably spout in the mulch, sending their roots through the landscape cloth into the soil below. Aggressive weeds beneath the landscape cloth will force their way upward through the barrier. Over time, weeds and roots become so embedded in the landscape cloth that the only way to remove them is to remove the cloth itself.

Today’s final tip: the internet-famous homemade weed control spray of salt, vinegar and blue dishwashing soap does not kill weeds, and neither does dousing your weeds with boiling water. Both methods damage the above-ground structure of the plant and may make the plant appear dead or dying, but the plant’s roots are not affected. To kill a plant by spraying its leaves requires applying a systemic weed killer – the toxic chemical stuff from the store – which is absorbed into the plant itself and kills the roots over a one-to-three-week period.