Some Weeds Were Not Always Weeds

Pampas grass was planted intentionally a long time ago, but then became a weed.

Weeds can be so very sneaky; getting into the weirdest places, and taking on all sorts of forms. They are mostly annuals or perennials that infest lawns and beds, but can be shrubs, vines and even big trees that grow among desirable plants, in untended areas, in cracks in pavement and even in roof gutters and on flat roofs. Many look appealing at first, but then later get out of control and displace the plants around them, or wreck whatever fence, pavement or building they encounter. Heck, I even suspect that it was a weed that stole my neighbor’s Pontiac!

While the soil is still damp from earlier rain, the most common annual weeds that are just developing are easiest to pull. They will put up more of a fight later, after they have dispersed roots, and the soil has gotten a bit more firm. Perennial weeds that were already established before winter will be considerably more stubborn, but not as stubborn as they will be as the soil dries later. Bermuda grass and crabgrass are always nasty.

The biggest, sneakiest and most stubborn weeds are ironically descendents of substantial perennials, shrubs and trees that were once actually planted in gardens. They are sneaky because they look as pretty as their parents when they first appear, in order to dissuade us from pulling them. The problems are that they are often too abundant, and very often get into spots where they will be problematic as they grow.

For example, Acacia dealbata and black locust are rather appealing trees while they are young, especially when they bloom. This is why they were originally planted in local gardens. It is tempting to allow self sown seedlings to grow instead of pulling them when they first appear. However, because they were not actually planted strategically where they can necessarily be accommodated, they grow in random situations, too near to pavement, fences or eaves, or in areas that are already landscaped. As they mature, they can damage these features or the plants around them.

Privet, pampas grass, castor bean and a variety of palms, acacias, ivies and several other plants that do a bit too well in local gardens have certain potential to become invasive or aggressive big weeds. Tree of Heaven, giant reed, the various brooms and the most invasive of acacias  have not been available in nurseries for many years because they are so problematic, but continue to be some of the most invasive and aggressive weeds in California.


Weeding Before Weeds Start Seeding

Some cultivated species can become weeds.

Weeds are weeds simply because they grow so aggressively where they do not belong. They begin before the weather gets warm enough for desirable plants to grow. Some are already blooming and dispersing seed. This is why weeding is presently very important. Weeds innately compete with desirable vegetation for space, water and other resources.

Weeding should ideally eliminate target weeds before they disperse seed. Some weeds are sneaky. They bloom and disperse seed while young and seemingly innocent. Some conceal their bloom and seed with their lush foliage. They seem to know to do so during rainy weather that discourages weeding. They effectively provide their own replacement.

Some weeds regenerate vegetatively. They grow from stolons, rhizomes, bulbs, corms or other dromant storage structures. Many of these structures were dormant through winter. Some were dormant even longer. They are aware that winter is becoming spring, so now begin to grow. As they do, they generate more of the same structures, perhaps with seed.

Weeding is easiest as soon as weeds are big enough to grip. Their young roots separate easily from their soil before more thorough dispersion. Also, their soil remains thoroughly damp and soft from winter rain. However, it may be easier to eliminate a profusion of tiny seedlings by tilling. Weeding bulkier weeds, such as pampas grass, can involve digging.

Only a few weeds are woody vines, shrubs or trees. More weeds are perennial. The vast majority of weeds are annual. Regardless, the most substantial weeds are woody. Some can regenerate persistently from their stumps. Therefore, weeding of such weeds should involve removal of their entire stumps. It is important to dig rather than cut oak seedlings.

Few native species proliferate undesirably. Therefore, most weeds are exotic. Most were originally desirable, but naturalized. English daisy, periwinkle, pampas grass and broom were formerly popular flowers. Blue gum eucalyptus formerly provided wood pulp. Other weeds formerly grew as vegetables, fruits or grain. Many weeds were once forage crops.

Acacia dealbata

It is an aggressively invasive exotic weed, but at least it is pretty about it.

Some of the worst weeds in California are substantial naturalized trees. The most famous of these is probably the Tasmanian blue gum (eucalyptus), which gets very big very fast, and crowds out other trees and plants in the process. The silver wattle, which is most commonly known locally by the Latin name Acacia dealbata, is even more voracious and prolific. It may seem simple enough to cut down an invading Acacia dealbata before it gets too big, but the seedlings from the original tree may continue to invade unrefined landscapes or wildlands for years afterward.

Even urban Acacia dealbata that lack space to disperse seed are problematic. After only about thirty years, they begin to deteriorate, but can die a slow unsightly death for another ten years! Deteriorating trees are likely to fall without much warning. They can get  more than sixty feet tall, and typically fall intact, so can do considerable damage.

The only attribute of Acacia dealbatais that it can be so visually appealing. The somewhat gray, bi-pinnately compound foliage is very finely textured, and provides just enough shade without being too shady. (Bi-pinnately compound leaves are divided into smaller leaflets, which are also divided into even smaller leaflets.) Individual leaves are about three to five inches long. The fuzzy staminate (lacking petals) flowers that bloom in winter are so abundant that most of the foliage is obscured. The floral fragrance that is objectionable to some is appealing to others.

Catch Weeds Before They Go To Seed.

Seed pods not only look unkempt and inhibit continued bloom, but can disperse too many seeds of otherwise worthy plants.

It may seem futile to pull certain weeds this late in the season. Those in unrefined parts of the garden that get little or no irrigation might be so dry that they only deteriorate and scatter their abundant seeds when pulled. The soil may be so dry that roots are difficult to extract, especially since the drying foliage now separates from the roots so easily. The only hope is that removal of dying weeds might eliminate at least some of the seeds for the next generation of weeds.

Foxtail and burrclover are not only annoying, but are also dangerous to dogs and cats as their seeds mature and dry. After all, the seeds rely on animals for dispersion, so intentionally stick to fur. The problem is that seeds can get stuck in more than fur, and sometimes get into ears, eyes, nostrils and elsewhere. Seeds from a few other weeds can do the same.

Cheeseweed is not a dangerous weed, and is relatively easy to eradicate. The roots even stay attached to the stems when they get pulled. The problem with leaving them to mature is that they become infested with rust (a fungal disease) that spreads to other desirable plants. Saint John’s wort, snapdragons and roses are particularly susceptible to rust.

Feral Jupiter’s beard and montbretia that grow where they were not intentionally planted are often allowed to bloom before getting pulled. However, after bloom, stems separate so easily from roots that most of the roots remain to regenerate as soon as they are able. If left long enough after bloom, both Jupiter’s beard and montbretia sow seeds to infest even more.

Fortnight lily (or African iris) are not often a weed, but can get that way if their seed capsules are not removed before they mature and pop open. Besides, development of these capsules diverts resources from continued bloom. It is best to remove the capsules before they get floppy, and to remove as much of the finished flower stem as possible without removing stems that have not yet bloomed.

Both dusty miller and coleus are grown for their distinctive foliage but not their bloom. Flowering stems stretch and exhibit inferior foliar color and texture, so can actually get snipped before they bloom.

Blue Gum

Juvenile blue gum foliage is very aromatic.

This is the primary eucalyptus that earned a bad reputation for all other eucalyptus. Blue gum, Eucalyptus globulus, arrived in California in the 1850s, and grew on plantations for timber. As its timber proved to be of inferior quality, and demand for wood pulp dwindled, the plantations succumbed to abandonment. Feral trees naturalized into adjacent areas.

Although once a common timber and wood pulp commodity, and effective as windbreaks for agricultural purposes, blue gum was never popular for landscapes. Those that inhabit urban or suburban situations were generally there prior to urban expansion around them. They are far too massive, messy and combustible, and inhibit the growth of other plants.

Mature blue gum trees can be significantly taller than a hundred feet, with elegantly high branched form. Limbs that fall freely from such heights are very dangerous. The aromatic foliage is evergreen. Adult leaves are stereotypically lanceolate and curved. Silvery blue juvenile leaves are blunt, sessile (lacking petioles) and more aromatic than adult foliage. Strips of smooth tan bark shed to reveal paler bark.

Exotic Weeds Are The Worst

English daisy gets prolific in lawns.

Exotic species are not native. It is that simple. There is nothing fancy about it. They came from elsewhere to live here. They are not necessarily rare, unusual or innately desirable. Most plant species within most refined landscapes and home gardens are exotic. Native species that inhabit unrefined areas, although trendy, remain unpopular for landscaping.

Not only are exotic plant species not necessary rare or desirable, many are too common or undesirable. With few exceptions, the most aggressively invasive of weeds are exotic. For a variety of reasons, they proliferate faster than native species. Some are aggressive because they are endemic to competitive ecosystems. Most lack natural pathogens here. 

A weed is merely any undesirable plant. Some might be desirable in some situations but not others. English ivy, for example, which is a practical ground cover within landscapes, is also an aggressively invasive weed within coastal forests. Most weeds are annuals or biennials, but others are perennials, shrubbery, vines, aquatic plants or substantial trees. 

An unfortunate reality about exotic weeds is that they are not here by mistake. Generally, their importation was justifiable at the time. Most were ornamental plants for gardens and landscapes. Some came as fruits, vegetables, herbs, cover crops or forage for livestock. Some came as timber. Species that escaped cultivation and naturalized became weeds.

Such weeds compete for the same resources that desirable plants utilize, and are mostly visually unappealing. Some enhance the combustibility of landscapes and forests. A few weeds produce seed structures that are hazardous to pets and wildlife. Even if problems are not directly obvious, weeds disperse seed to share their innate problems elsewhere.

This is typically the best time of year to pull or grub out weeds, although more weeds will grow later. Annual weeds are mature enough to get a good grip on. Soil should be damp enough from winter rain for roots to pull out relatively easily. Weeding will likely require a bit more effort this year because of the extended dry and warm weather since December. 

Not all weeds are unwelcome.

Unplanned acacias certainly put on a show when they bloom. It is not easy to dislike something so impressively colorful.

Even the best tended gardens get weeds. Most weeds, particularly annual and perennial weeds, meet a quick demise by getting pulled out or sprayed with herbicide. A few shrub and tree weeds though, are sometimes allowed to mature into functional members of the landscape.

Many sneak into the garden by growing within overgrown or otherwise concealing shrubbery, where they can hide long enough to get established. Others are left to grow because they are recognized as desirable plants. The main problems is that many end up in situations where they eventually become problematic.

Mexican fan palms are distinctive trees. Unfortunately, many grow below utility cables, because that is where birds drop the seed as they eat the fruit. Unlike other trees, palms can not be pruned around utility cables, so must be removed when they get too tall.

Silk tree, black locust, tree of Heaven and various oaks, pines, acacias and eucalypti are some of the more common trees that can sneak into gardens. Sometimes, they happen to land in good situations. More often though, they get too close to foundations, eaves, pavement or other features that they damage as they grow. Like Mexican fan palms, they are easier to remove while young, before they become problematic.

Pittosporums, cotoneasters and privets are commonly seeded shrubbery with less potential for problems. The main problem with glossy privet is that it can be too prolific and aggressive, so that it can crowd out more desirable plants. Most pittosporums and cotoneasters that get seeded are from plants that are ‘straight species’ (not cloned cultivars or varieties). Those that happen to be from cultivar or variety plants will not be ‘true to type’, which means that they will be more like the straight species than like their parents.

The few fruit trees that can sometimes grow from seed have the same problem, since only some of the more genetically basic types may resemble their parents. Fancier types and (non-sterile) hybrids probably will not. Fruit trees that grow from root suckers of grafted trees instead of from seed will be nothing like the parents, and may produce useless fruit.

Pampas grass is a prolific and sometimes welcome perennial weed near untended parcels or forested areas where pampas grass has naturalized. Broom is a shrubby weed that is even more prolific, but never welcome.

Algerian and English ivy rarely grow from seed, but can be really nasty weeds if they get where they are not wanted. Bear’s breech (or breaches), Jupiter’s beard, calla, mint and various yuccas that were planted may be very difficult to eradicate if they are no longer desirable, or if they migrate into areas where they become problematic.

Six on Saturday: Ghost Town

As a result of prioritizing our efforts within the landscapes at facilities that have been in use through summer, landscapes at unused facilities have been neglected. It would be embarrassing if anyone else were here to see the results. Those who maintain the other infrastructure have mentioned that these neglected areas resemble ghost towns. Flowers continue to bloom without any assistance. Also though, weeds continue to grow and toss seed for the next generation. There is so much to catch up on. What is worse is that I will not be working here much until November, and will be gone again in February.

1. While no one is looking, lily of the Nile continues to bloom into the middle of September. I was not here to see it, but I suspect that this particular colony was not blooming on time for July.

2. Kahili ginger is blooming too, but right on schedule. This is obviously a substandard bloom. I am impressed nonetheless. It was not expected to bloom at all. It was just planted over winter.

3. Otherwise, most of the bloom here is that of weeds. Strangely, I do not remember anyone pulling weeds from the pavement before. Could the formerly constant traffic have inhibited them?

4. Should this say “PLEASE LET US GROW ON WALKWAYS” or maybe “PLEASE LET US STAY ON WALKWAYS”? Regardless, I am impressed by the ability of weeds to compose a sentence.

5. Grapes would certainly be easier to reach if they grew on neglected, hanging vines like these. Unfortunately, if left long enough to produce fruit, these vines would become a tangled thicket.

6. Goodness! This is what happens when a ponderosa pine seedling grows under a deck, and no one is here to pull it out before it grows right through! The weed problem here is now serious!!!

This is the link for Six on Saturday, for anyone else who would like to participate:

Online Plant Purchases Have Certain Risks

Many seeds can be found online.

So many plants that were difficult to obtain years ago are now much more available online. The internet does more than give everyone access to nurseries and seed suppliers that sell online. It also makes it possible to communicate with others who might want to share plants and seeds from their own gardens. The advantages are obvious, but there are innate problems with so many plants being too available.

Before humans started to relocate plants all over the world, plants were much more confined to certain regions. Once relocated to new regions, some plants naturalized and became problematic for the plants that were already there. Exotic (non-native) plants often had the advantage because pests that troubled them back home had not come with them.

For example, pampas grass had been confined to the Pampas region of South America. It was imported to California and Oregon because its fluffy flowers and graceful texture are so appealing. The problem now is that it naturalized, and continues to proliferate and crowd out native plants in coastal ecosystems, without natural pathogens to slow it down. The availability of so many more plants from so many more regions seriously increases the potential for the importation of invasive exotic plants, as well as plant diseases and even insects!

Another potential problem is that common names of plants can be very different in different regions. Now, this can be an advantage when seeds from a common yucca in Lubbock, Texas might actually be from the very uncommon plains yucca (Yucca campestris, which I recently purchases on Ebay!). The problem is that the yucca known as ‘Adam’s needle’ in Georgia may be a completely different species from what is known as such in Pennsylvania, Oklahoma or anywhere else. A plant described as a ‘mimosa’ could be a silk tree, a jacaranda tree, or any of several different acacia trees!

Mulch Is Lowly But Practical

Mulch is less interesting than useful.

Gardening is unnatural. Most popular plant species are not naturally native. Cultivars are products of unnatural selection and breeding. Most plants like unnatural watering. Some enjoy unnatural fertilizers. Removal of their detritus is unnatural. So is the replacement of their detritus with mulch. Actually, most of what happens in the garden is quite unnatural. 

Ironically, gardening is how many of us incorporate more nature into our lifestyles. Much of our effort compensates for what plants naturally crave but unnaturally lack. Watering is necessary for plants that get rain through summer within their natural ecosystems. Mulch might be nice for plants that naturally benefit from the decomposition of their own debris.

In nature, most plants benefit from their own debris. They enjoy the nutritiously decaying organic matter and enhanced moisture retention. Their shallow roots enjoy the insulating effect on the surface of the soil. Debris of some plants excludes other competitive plants. Mulch is not a perfect substitute for such detritus, but partly compensates for its removal.

Although it would likely be an asset to the plants that produce it, the detritus produced by most plants can not stay in the garden. Much of it is too abundant. Some is too shabby or too coarsely textured. Some might become combustible as it accumulates. Diseases can overwinter in some types of debris. Mulch is more sanitary, neater and less combustible.

Most mulches are organic matter of one sort or another. Compost does not last long as a mulch, but is appreciated by most plants. Uncomposted chips from a tree service occupy nitrogen as they decompose, but are more effective for inhibiting weed growth. Products that are available as mulch at garden centers are more refined, but also more expensive. 

Some dense ground cover plants perform something like mulches. Many consume more moisture than they retain though. Also, they can retain bits of potentially infectious debris that falls from diseased plants above. Nonetheless, they insulate the surface of their soil, and inhibit or exclude weeds. Gravel over ground cloth is inert, but requires no watering.