Tag Archives: weeds

How To Identify Weeds in Your Garden

Identifying weeds might not rank up there with ridding the garden of the invaders, but it often drives me mad when I can’t identify a weed. It’s more important to know a weed from a desired plant or wildflower, so you know whether to leave it alone or destroy it before it spawns and takes over your garden.

So, how can you tell a weed from a flower? Here’s a definition I received from a weed scientist with New Mexico State University in their master gardener training materials: “A weed is any plant that interferes with the management objectives for a particular site or situation.” That’s actually a brilliant definition (must be because he is an expert). Here’s why:

One gardener’s weed is another gardener’s favorite fauna, but with some caveats. In other words, if you love dandelion flowers and want to leave them in your garden, then maybe dandelions are not a weed. If you leave purslane to grow because it’s an edible weed (as are parts of the dandelion), then more power to you. But if the purslane begins to cover your thyme or the dandelion chokes out the small area of grass you have in your lawn, do you shift them into the “Weed” column?

mexican hat

Mexican hat (Ratibida columnifera) seeds all over our garden. It’s a fun summer flower, but was recently host to what looked like baby cucumber beetles. It also grows tall and blocks sun and air from getting to nearby plants. I pulled a bunch of them.

Another way to look at it is to peg a weed according to some criteria set by the Weed Science Society of America. According to their site, weeds have common characteristics, including:

  • Production of way more seeds than normal – up to tens of thousands from a single plant.
weed seeds in garden

No, we didn’t scatter feathers on the ground. Those are weed seeds, in a bed we worked on at least twice. There’s also an elm tree sprouting — extra credit if you spot it.

  • Long survival time for seeds, which can remain dormant in soil until just the right weather or other condition triggers growth.
  • Rapid establishment (yes, they really can crop up nearly overnight).
  • Mechanisms that support easy spread.
  • Ability to grow in places where other plants can’t, such as between rocks or in poor, dry soil.
field bindweed

Field bindweed, aka wild morning glory. Sure, give it a pretty, regular name. It grows anywhere, and especially loves rocks AND rose trunks so it can hide before it chokes the life out of the poor rose.

If you look at the one attribute that all of the points above have in common, it’s this: survival. I can’t count how many times we’ve sowed some flower or vegetable seed at just the right depth, watered it regularly and checked daily. Nothing. But weeds – they keep returning for encores, even when you try to destroy them!

Aside from persistence, the ability to outcompete nearly any plant and your best efforts to remove it, there are a few other ways to tell  a weed from a regular plant when you’re examining it in your garden. For example, the characteristics that help weeds spread their seeds might show in their appearance. Hooks, spines and stickers make them harder to pull. And some have adapted attractive flowers to fool gardeners. A tap root often is a sign of a weed, or at least a plant’s survivability. You can pull and pull, but if you break the root off, it comes back and is somehow stronger than ever. Rhizomes or stolons also help weeds spread just underground, especially grassy weeds. And some weeds have asexual properties so that they can reproduce plenty of new plants with no floral fertilization.

dandelion in gravel

Dandelions have telltale spiny leaves, a tap root and lots of seeds after flowering.

In short, if a plant is wrapping around another plant, cropping up on, under or around a plant so that it affects your desired plant’s ability to use sun and water, call it a weed. We have some gorgeous volunteer wildflowers that come up each year in our garden, but we don’t keep all of them. If they crowd out another plant or cause so much shade around roots that a rose gets fungal during the monsoon season, they’ve got to go. I’ll keep a few of them, which means I’ll have to thin again in the future. But I won’t call them a weed.

I’ll post some of the worst New Mexico offenders in the future. For now, if you need help identifying weeds, check out the tool and external links under the WSSA’s Weeds section on their menu. I’ve also posted some new links on my Resources page.

Another Reason to Weed Your Garden: Water Savings

If you’re like me, you hate the sight of weeds in your ornamental or vegetable garden, and you have permanently discolored cuticles from April through September.

Weeds are more than unsightly, however. Ask any farmer, who knows that weeds can reduce their crop yields by at least 50 percent by simply robbing crops of water. Although weeds can seemingly grow out of rocks, parched dirt or sand, they still compete with surrounding plants for water. Weeds also host bugs and diseases and can block sun or air circulation to important plants. For example, if a tall weed shades your bell pepper plant, the plant is less able to compete for water and nutrients and less likely to produce as many peppers. Some weeds even introduce chemicals that are toxic to certain plants, animals and people.

Weed growing in middle of sage

This culinary sage has a weed growing up through the middle of it. The weed’s tap root likely steals rain water from the sage.

Are you hating weeds as much as I do yet? There are those who tout their benefits. A few weeds provide nectar for bees or help supply organic matter to soil. And as I’ve mentioned before, there is a fine line between weeds and wildflowers. Our widespread alyssum invasion each spring adds early color and brings hundreds of bees to our land.

Further, several weeds are edible. Examples that come to mind are dandelions and purslane. But I really prefer carrots and cucumbers.

According to Robert Parker, Ph.D., of Washington State University’s Cooperative Extension Center, it’s more important to control weeds during drought than during typical years. And some common weeds consume more water than typical crops. An example is Russian thistle, which Parker said removed nearly 18 gallons of water per plant while competing with a spring wheat crop. The thistle is just one of the weeds we are trying to attack here on our property and a priority throughout Lincoln County, N.M.

thistle weed

This thistle (to the upper left of Buster) is growing in our ditch, along with a horehound and numerous other weeds. I need to grub it before it goes to seed.

Parker says that crops are most affected by weeds during early growth. So home gardeners are best served by prepping their gardens carefully to start out with a clean slate and to handpick weeds until their backs give out. Seriously, it’s always best to keep weeds under control without chemicals if possible. That’s especially true during a drought, because most herbicides require water to work effectively.

In fact, weeds are the ultimate native plant! They adapt to drought by developing ways to retain moisture in their tap roots or waxy layers on leaves. When drought affects grass growth on rangelands, more weeds move in and establish squatters’ rights. That’s what seems to have happened to us. We now have a proliferation of several weeds, and especially horehound (Marrubium vulgare).  Horehound grows best in dry soil, and I’ve seen it growing in the worst places possible.

horehound

Horehound, which is considered a good plant or an awful weed.

From what I can tell, horehound spreads by seed, but also has runner-type roots and maybe spreads just by magic. It’s in the Lamiaceae, or mint, family. Need I say more about its invasive qualities? And although a noxious weed in some areas, horehound also is considered one of those “good” weeds, having both medicinal properties and use as an edible for tea or candy. But I point to the “vulgare” portion of its name. If it continues to take over our grass, I might give in and learn how to make the vulgar weed into candy, which apparently tastes like licorice.

horehound spreading

Horehound mowed down to prevent seeding, like that will help. It is taking over this grassy area.

Most likely, we are going to require herbicide at some point. By the way, the horehound noxious weed spread began when it was introduced to ornamental gardens. I’m all for growing edibles, but why not mint in a container?

Weed or Wildflower?

Water-wise gardening in the Southwest means accepting the spread of native wildflowers and using them to fill and brighten a landscape or garden. There’s a fine line between weed and wildflower, however.

Some native species spread so easily under the right conditions that they take over a garden. Others might not be native, but were introduced to an area and thrive when Mother Nature cooperates. That’s why we had a “yellow spring.” Last fall, we noticed pretty little spiral seedlings appearing in the dying grass. We wondered what they were, but left them. In the spring, yellow popped up everywhere.

 

yellow alyssum in New Mexico lawn

Is it weed or wildflower that spread like crazy in early spring? It got yellower and was pretty, but weird.

Don’t get me wrong; it was beautiful. But I spent hours trying to identify the weed. I knew it probably was related to mustard, but it didn’t match any of the typical mustard weeds I could find in my searches. And I searched, and searched, for wildflowers and weeds. Here’s a close-up of it in the garden. And guess what it is?

yellow-alyssum

Alyssum is usually a lovely annual in flower beds. Here is yellow alyssum in our rock garden, where it also grew like crazy.

It’s yellow alyssum, or Alyssum alyssoides,  a member of the mustard family, imported from Europe. And it has both good and bad qualities. I’ve purchased sweet alyssum before as a bedding plant. And in some searches, it’s listed as a great choice to bring beneficial insects. I can vouch for that, because as I walked across our property on a sunny day, there was a low buzz – bees everywhere. I loved it, but it was a little freaky. And I saw one doe get stung on the face.

Alyssum also is listed as a weed in many Western states. It’s got a taproot about a mile long (slight exaggeration) and really only comes up completely if you moisten the soil and pull. I’ve seen conflicting information on whether it threatens native grasses. We’ll know more as spring progresses.

In the photo above is another weed/wildflower: a native verbena (species Glandularia). I’ve bought plenty of verbenas for rock gardens in lovely colors. And these are beautiful too, especially coming up between the yellow alyssum out in open grassy areas. They are more leggy and leafy than the hybrid or garden-variety verbenas, however, and will come up just about anywhere:

verbena-weed-new-mexico-xeric-rock-garden

Wild verbena looks pretty against rocks, not so much all over a gravel path.

Now, I have wildflowers I love that spread like weeds, usually by self-sowing. We usually leave them in place. Some are great for color and flower, some for scent. And the beauty is that they adapt so well to the dry conditions that they fill the garden without us having to purchase, plant, and most of all, water new plants.

An early spring favorite is night-scented stock, also called night stock (Matthiola longipetala). Believe it or not, it’s also a member of the Brassicaceae, or mustard family. The scent in early evening is so pleasant, and we love that these come up near the patio. They’re also reseeding in the grass around the garden!

night-scented-stock

Night stock has a delicate and pleasant scent that comes out with its blooms in early evening.

The blanket flower (Gallardia) has always been a favorite and the previous owners made sure we have plenty in our garden. They thrive in drought and have such vibrant colors, as do Mexican hats, or prairie coneflowers (Ratibida columnifera).

mexican-hat-prairie-coneflower

Mexican hats, or prairie coneflowers, pop up everywhere in our garden. These look terrific next to perennial yarrow.

We even admit to leaving a few alyssums intentionally where they complement another plant or look pretty up against a rock or piece of dried wood. We’ll never be able to pull them all or stop the reseeding, and I’m not sure we should. They do attract bees and offer early spring color. But it’s hard enough to get grass to grow in a drought and through various weeds. If alyssum adds to the competition too much, we’ll probably need help finding a control method.

Update in March 2015: The alyssum didn’t choke out the grass last year. It might have delayed grass taking root in a few spots, but we had a beautiful lawn. And yep, it’s already back. I’ve come to accept it, and just want to keep it from spreading across an irrigation ditch to our orchard area. Tim is trying to pull it out of the rock garden beds. I don’t have the energy to fight it. But it’s fun to watch…