Weeds Are Full Of Surprises

Pokeweed is rapidly becoming more common.

While it was busy naturalizing in Australia, South Africa and southern South America, the California poppy was getting forced out of parts of its own native range by more aggressive exotic plants that were also busy getting naturalized. Technically, any plant that is not native is exotic. Any exotic plant that becomes naturalized in a foreign environment is able to proliferate without any help, as if it were native. Naturalized exotic plants that get too aggressive become invasive weeds.

Weeds are plants where they are not wanted. This is a very broad definition that includes plants ranging from simple little dandelions in urban lawns to humongous bluegum eucalyptus in forests. Naturalized exotic weeds can be much more problematic than weeds that can only proliferate where they get watered in gardens and landscapes, because they can get established where they are not expected.

Water hyacinth that clogs the Sacramento and San Joaquin River Delta is not often a problem in terrestrial landscapes. However, giant reed, pampas grass, Acacia dealbata and blackberry brambles can infest home gardens just as easily as they infest wild lands. Because they do not need to be watered, they can get established and grow quite large in unused parts of the garden before anyone notices.

Many naturalized weeds somehow seem to much more aggressive and problematic than even the most prolific of native plants. Even the common native lupines are relatively docile compared to annual oat grass. Native blackberry may seem impossible to eradicate, but is actually neither as persistent nor as unpleasant to handle as the exotic Siberian blackberry!

Young weeds are easiest to pull now while the soil is still evenly damp, and young roots are only beginning to disperse. They will be more difficult to pull after roots are dispersed and soil hardens. Tree weeds and large perennial weeds that were cut down last year instead of pulled will likely need to be dug. Bermuda grass is a relatively low perennial grass that always seems to be difficult to dig. Mowing or cutting down annual grass weeds with a weed whacker will not eliminate them, but limits the development and dispersion of seed for the next generation. Burclover, sowthistle, bindweed, purslane, spurge and the various oxalis are some of the other common weeds that really get going this time of year.

Invasive Weeds Waste No Time

Aggressively invasive exotic species become weeds.

With few exceptions, the most aggressively invasive weeds here are exotic. In other words, they are not native. They came from other regions where they were likely compliant participants of their respective ecosystems. At home, where they must compete with other members of their ecosystem, they may not be so aggressively invasive. Ecology is the opposite of a home field advantage.

Exotic species become invasive weeds in foreign ecosystems for a variety of reasons. For some, the climate is more favorable. Some grow and proliferate more freely without diseases, insects and animals that troubled them back home. There are also several that simply compete more aggressively for space and resources than native species are accustomed to. It is a jungle out there.

Most invasive exotic species are annuals. Many are biennials or perennials. Some are vines, shrubs or even trees. Most were imported intentionally, for a variety of reasons, and then naturalized. Forage and cover crops were some of the earliest of exotic species to become invasive. Other invasive species escaped from home gardens. Blue gum eucalyptus was imported for wood pulp.

Regardless of their origins or physiological forms, invasive species are weeds. They compete for the same resources that desirable plants use. They impede on the aesthetic appeal of gardens and landscapes. Some types of weeds become hazardously combustible. Even if not directly problematic, invasive weeds disperse seed that can be problematic nearby. Many disperse stolons.

Most weeds start early and grow fast to get ahead of their competition. They are more active at this time of year than at any other time. They are also vulnerable. While the soil remains damp from winter rain, they are relatively easy to pull intact. They have not yet dispersed seed for their subsequent generation. Later, they are likely to leave behind seed and bits of roots that can regenerate.

It is important to pull or grub out seedlings of unwanted shrubbery and trees, as annual weeds. They are likely to regenerate if merely cut.

Snails, Weeds And Falling Leaves

Gardening does not slow for autumn.

The coloring of foliage is a bit slow this autumn. The cooling nights after such warm weather is bringing some of the deciduous foliage down while it is barely yellowing. Honeylocust and black oak have already gotten notably sparse without much notable color. Hopefully, the more colorful sweetgum, flowering pear, pistache and gingko trees will retain their foliage later into cooler weather, so that they can put on a worthy show before filling compost piles.

It is probably slightly too early to clean gutters and downspouts. Unless the rainy season somehow starts first, this should probably wait until most of the foliage that is expected to fall has already fallen. Lawns, certain ground covers, decks and pavement should be raked as needed though. Decks and pavement can get stained from the tannins that leach from decomposing foliage. Lawn and ground cover do not like the shade under the debris.

However, slugs and snails really dig the mess. Fallen foliage keeps the ground cool, damp and shaded. Raking leaves does not eliminate slugs and snails, but inhibits their proliferation. There are always plenty of other hiding places. As the weather eventually gets cooler and damp, snails that stay out in the early morning should be collected and disposed of. Of course this technique is not convenient for everyone, since most snails hide before the sun comes up. Small slugs hide earlier in the morning and are even more unpleasant to handle.

Once found, neither slugs nor snails are too elusive . . . or fast. Yet, plucking and collecting them is not a fun job. Once collected, no one knows what to do with them. They can be put into plastic bags and disposed of; and will eventually succumb. Some people prefer to simply toss them onto a dry and sunny driveway or roof where they succumb more quickly and get taken by birds. Snails may need to be squashed to limit mobility.

Even though it is too late to prevent most types of weeds from dispersing their seed, a few types continue to disperse seed as they deteriorate through autumn and winter. Weeds in areas that get watered last longer and disperse their seed later than those without watering. Perennial weeds that are still green in dry areas areas will be easier to pull after the first rain.

Weeds?

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Although I can not be certain, I believe that this is prickly lettuce.

Pretty weeds do not get my attention like they do for others. They look too much like weeds to me. If I want to appreciate them, I must do so with intention. Sometimes, I do actually try. I did happen to notice these two weeds. However, now that I got their pictures, I have no use for either of them. Neither is readily useful for the gardening column. I will just share them here.

The yellow flower pictured above is most likely prickly lettuce. I really do not know. I know it as yellow chicory; but chicory does not bloom yellow. Some people think of it as dandelion, since the flowers are similar. These flowers stand much higher though, with only minimal foliage below. For the picture, I plucked this flower and stuck it in the ground to keep it still in the breeze.

The white flower pictured below is common bindweed. When I was a kid, I knew it as morning glory. In this close up picture, it looks like a fancier garden variety of morning glory, although the flower is much smaller. Real morning glory happens to look good in white, like this one does. If it is fragrant, I have never noticed. It tends to creep along the ground more than it climbs.

It sometimes seems silly to me that others so easily notice how pretty weeds such as these are, especially while there are so many more flowers that are prettier. Then, I realize what others must think of what I consider to be pretty. For example, the pollarded blue gum with aromatic blue foliage that I enjoy so much, is the same species that gives all eucalypti a bad reputation.

Besides, these flowers were the prettiest in the otherwise bare meadow where I found them.

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Bindweed looks like miniature morning glory.

Too Much Oregano

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Herbs should do so well in an herb garden.

Vegetation management after several weeks of neglect has been . . . interesting. While we were unable to work, and during their most active growth of the year, weeds proliferated more than they had ever gotten away with before. As most get cut down by weed whackers, I pull those that mingled with desirable plants that weed whackers must avoid. It is a tedious process.

One of the more tedious of these projects, and perhaps the most tedious so far, required the removal of abundant weeds from a dense row of carpet roses. Fortunately, it was not as bad as I expected it to be. They young man who weeded this area during winter had done a remarkably thorough job, and eradicated most of the dreaded oxalis and tougher perennial grassy weeds.

The weeds that I pulled were big and impressive, but pulled out relatively easily. A few thistles were unpleasant to handle, but even they came out easily. Mock strawberry between some of the roses was still in good condition after the weeds that mingled with them were gone. I realize that I do not adequately appreciate all the weeding that happens here that I am not aware of.

Besides mock strawberry, another species that gets to stay in parts of the area that it spreads into is some sort of oregano. It seems to be common Italian oregano, but also seems to develop leaves that are slightly larger than they should be. It is too docile to be a problem for the roses, but occupies space that would otherwise be taken by weeds. Besides, it is nice to have around.

Even oregano needs to be managed sometimes. Quite a bit of it got pulled from the roses along with the weeds. I suppose it must be dried now.

While You Were Out

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It’s a jungle out there!

Our work is the sort that could potentially continue as essential. Distancing is not a problem for us, since we generally work individually, and there are no guests here. However, work needed to be discontinued due to lack of revenue. A conference center can not generate revenue without big groups of guests. Even when groups can return, many potential guests can not afford to.

The chronology of this situation should have been documented more efficiently. We had been unable to work here for several weeks. I do not remember how long it had been. Work resumed two weeks ago, and can continue for six more weeks, for a total to two months. We will start no new projects during this time, but will primarily try to catch up on what was neglected earlier.

Salvage and preparation for resumption of neglect are presently the priorities. This entails vegetation management after weeds had been left to grow wild during their most active season. It is extreme. Most weeds either had dispersed their seed, or did so as they got removed. This is not much of a problem for areas that are not landscaped, but will be trouble within landscapes.

Weeds in areas that are not landscaped get cut down by weed whackers, and mostly left where they fall. Roots that remain within the soil, and debris dispersed over the surface, should limit dustiness later in the summer. Weeds in landscaped areas and where weed whackers can not get into must be pulled. We do not want young desirable plants to be ruined by weed whackers.

It is discouraging that no one is here to enjoy the landscapes that we put so much effort into while we can work. It is also discouraging to see how easily the landscapes can fall into disrepair.

Some Seeds Can Hurt Pets

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Foxtail is a potentially dangerous weed.

Weeds always have unfair advantages. They grow fast enough to bloom and disperse seed before the rain of early spring runs out, so they do not need any supplemental water. They seem to be able to grow anywhere. Their abundant seed seem to be able to get anywhere. Many produce seed with creative tactics for hitching rides on animals or being blown around by the wind.

This can be a serious problem for the unfortunate animals that interact with these exploitative weed seeds. Burclover and foxtail that are designed to stick to the short hair of grazing animals just long enough to get moved to greener pastures can get seriously tangled in the softer and longer fur of cats and dogs. Foxtail and other thin seeds can get lodged into noses, ears and eyes.

This is why it is so important to control these sorts of weeds, even if the landscape is not a priority. Gardens without resident cats can be visited by neighbor cats who can be hurt by dangerous weed seeds, or disperse the seed into other gardens. Mistletoe seed is not really so dangerous, but has a sneaky way of sticking to birds and squirrels for dispersion.

Thistles are more of an annoyance than actually dangerous. Their seed does not stick into fur. It just gets blown about in the wind. The problem is that the spiny foliage of some types is too painful to handle. If neglected long enough to go to seed, thistles can be seriously prolific. Because it is dispersed by wind, the seed can get anywhere without any help.

Weeds can be recycled in greenwaste, only because greenwaste gets sterilized in the recycling process. Some annual weeds can be composted if they get collected before they produce seed. If there is any seed, some of it may survive the composting process, and germinate wherever the compost gets used. It would be better to dispose of such risky biomass.

Likewise, crabgrass, dandelion, oxalis and other perennial weeds should not be composted because some of the stolons (modified stems) or roots survive the process. Just like seed, some of these surviving vegetative parts can grow into new weeds wherever the compost that contains them gets dispersed. Such resiliency is one of the qualities that makes them ‘weeds’!

Broom

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French broom seems to be indestructible.

Shortly after silver wattle finishes blooming up high, any of four species of broom begin blooming down low. Brooms and silver wattle often naturalize together. All bloom with the same delightfully brilliant yellow. The four brooms are French broom – Cytisus monspessulana, Scotch broom – Cytisus scoparius, Portuguese broom – Cytisus striatus and Spanish broom – Spartium junceum.

Sadly, none are desirable species. All are exotic weeds. They are only a topic for gardening because they are so aggressively invasive. Not only do they overwhelm and displace native species, but they also enhance soil nitrogen to promote the growth of other exotic weeds! They are unpalatable to deer, and are not bothered by insects or disease. Furthermore, brooms are combustible!

It is best to enjoy their cheery bloom from a distance, where they grow wild where they really should not. The various species tend to dominate distinct regions, with some degree of mingling. Big specimens can get eight feet tall, but do not live long as they are replaced by herds of seedlings. French broom is the only evergreen species; but any can defoliate in response to hot dry weather.

Exotic Species Can Become Naturalized

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Naturalized Himalayan blackberry is detestably aggressive.

Every palm tree in local landscapes is exotic. Simply put, all palms are originally from somewhere else. The desert fan palm, the only palm that is native to California, came from isolated colonies in desert regions many miles away. In fact, most plants in common landscapes are exotic. Landscapes composed of Californian plants likely include some plants from other regions of California.

With few exceptions, exotic plants are not a problem. However, some of those few exceptions have become very serious problems. Himalayan blackberry, blue gum, silver wattle, pampas grass, giant reed and broom are some of the more notorious examples. They naturalized to become prolific and aggressively invasive weeds. Some are more common than natives in many situations.

Naturalized exotic plants such as these are problems for local ecosystems, even if they do not affect refined landscapes. They compete with native plant species for limited resources, space and pollinators. A lack of pathogens from their homelands can be a distinct advantage. They alter the lifestyles of some of the native fauna. Some enhance the combustibility of the forests they inhabit.

The justifications for importing exotic species are as varied as the species themselves are. It might have been for lumber, forage, fruit, or vegetable production. Giant reed might have arrived here as packing material for cargo from southern Asia. Nonetheless, most naturalized exotic species, including the most aggressively invasive, came here simply for home gardening and landscaping.

Realistically, of all the countless exotic species that came here during the past few centuries, very few naturalized. Fewer are now aggressively invasive. Some with potential to naturalize may not have yet been able to escape the urban situations they inhabit. The problem now is that there are so many more exotic species readily available from all over the World than there has ever been!

Online marketing facilitates procurement of exotic and potentially invasive plant species from other regions, with minimal regard to regulation of such commodities.