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Autumn Is Time For Planting

Autumn is time for spring bulbs.

“Autumn is for planting.” This is a common marketing campaign among nurseries at this time of year. Also, it is generally true. Of course, as with most generalizations, there are some exceptions. Bare root season is during winter. Summer bulbs prefer planting after the coldest weather of winter. Many species nonetheless prefer planting during autumn.

Cooling weather is less stressful for new plants while they begin to disperse their roots. Yet, the soil is still warm enough to promote healthy root dispersion. Later, rain will keep the soil evenly moist and provide all the moisture new plants need. Even if growth is not evident above the soil, it is probably active below. Roots grow until cold winter weather.

Simultaneously, most common pathogens and weeds are less vigorous during autumn. Many diseases need spring and summer warmth to proliferate. Insects are similarly less active now that the weather is cooler. Although weeds have dispersed their seed, some of it will not grow until next year. New plants can have the whole garden to themselves.

Planting in autumn gives the plants an advantage next spring too. Although they appear dormant through winter, they slowly continue to disperse roots. By spring, their roots are more dispersed than they would be if planted in spring. They are ready to grow as soon as the weather warms after winter. There is less delay to disperse their sustaining roots.

Many bulbs and bulb like plants are naturally dormant by late summer or early autumn. Spring bulbs, such as daffodil, hyacinth, crocus, tulip and allium, will soon be in season. Not only are they dormant, but some also bloom better after vernalization by winter chill. Bearded iris are already dormant and ready for division. So are many larger perennials.

Because some plants are dormant or visually tired by now, some nurseries have sales. This could be a good time to purchase certain items at a discount. Daylily is an example of a perennial that begins to defoliate about now. Nurseries do not want to keep them in stock while they are dormant and mostly bare. New foliage develops shortly after winter.

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Autumn Weather Eventually Becomes Cooler

Some foliage turns color for autumn.

Cool season vegetables and cool season annuals might still seem early. The weather is not yet notably cool, although it is not as warm as it was for summer. Nevertheless, it is now autumn. The weather will become increasingly cooler and eventually rainier before winter. Plant growth will decelerate. Some foliage will become both colorful and messy.

As the weather cools, irrigation will become less demanding. Evapotranspiration, which is evaporation from foliage, decreases substantially. Deciduous plants defoliate, so can not transpire. Evaporation from soil also decreases. Rain will dampen everything that is not under a roof later in autumn. Then, irrigation will be redundant until the rain pauses.

Rain later in autumn typically accompanies storms. Stormy weather can damage trees, or potentially destabilize some. It is therefore important to address arboricultural issues now, prior to stormy weather. Arborists will be busy later, so may not be able to respond to emergencies immediately. After autumn, winter storms can be even more destructive.

As plant growth decelerates, pruning and mowing will become less necessary. Hedging may not be necessary again until growth resumes in spring. Late pruning can stimulate new growth. Such growth would be susceptible to damage from stormier winter weather later. Rain might sometimes delay lawn mowing, which should be less frequent anyway.

Some deciduous foliage becomes colorful as the weather cools and the nights lengthen. Even more of it becomes messy. As autumn progresses, it necessitates raking from turf and hardscapes. Unraked foliar debris causes mildew within lawns, and shades out the grass. Foliage also stains hardscapes, clogs drainage, and becomes a slipping hazard.

Gardening certainly evolves with the seasons. Some tasks become less demanding for autumn, or unnecessary. Others become more important. This autumn may precede an extreme El Nino winter. It is therefore advisable not to neglect garden maintenance as it becomes necessary. Minor concerns can become major when the weather gets stormy.

Posted on by tonytomeo · 14 Comments

Six on Saturday: Last Wednesday Again

Again, this Six on Saturday lacks a theme. These are six random pictures that I took last Wednesday morning.

1. Rain?! Well, actually, it was just drizzly fog. It certainly looked like rain, though, and it was enough to fill a few puddles, and be hazardous for commuter traffic on Highway 17.

2. Phlox paniculata, garden phlox that I got a picture of last week flopped forward from the weight of the drizzly fog. It stood more upright as the moisture dried later in the day.

3. Pinus thunbergii ‘Thunderhead’ Japanese black pine is generating new growth rather late. It probably should have done this in spring so its foliage would be matured by now.

4. Alocasia macrorrhiza, elephant ears is now blooming with its weird green spathe and spadix. This same blooming stem is already producing a new leaf, so is not monocarpic.

5. Hedychium gardnerianum, kahili ginger is beginning to bloom. It has not done much since its arrival a few years ago. Gophers typically ruin it before floral buds even appear.

6. Canna X generalis, canna bloomed with this strange orange and yellow combination, which we did not plant. It is a sport. Strelitzia nicolai, giant bird of Paradise is behind it.

Anyone who would like to participate in this meme should peruse this participant guide for Six on Saturday.

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Watering Resumes With Drier Weather

Irrigation becomes necessary without winter rain.

Even before the last day of winter on March 20, the weather went summery fast. Not only has there been no rain in quite a while, but it has become rather warm also. This climate here can be tricky like that sometimes. While moisture becomes less available from rain, it also becomes more necessary. Watering, or irrigation, needs to resume to compensate.

Watering had not been much of a concern during rainy weather through winter. Only pots and planters that are sheltered by eaves still needed it. Between rainy weather, cool and humid weather inhibited evaporation. Therefore, watering was rarely if ever necessary to compensate for a lack of rain. Even sheltered planters needed less than during summer.

Lack of rain and warmer weather are not the only reasons for the need for watering. Day length is slowly but steadily increasing. Sunlight intensity increases as the sun becomes higher in the sky. Lengthening days of intensifying sunlight accelerate the desiccation of soil. It also accelerates evapotranspiration, which is the evaporation from foliar surfaces.

Furthermore, warming weather accelerates growth of vegetation. This increases its need for moisture that rain no longer provides. Formerly dormant deciduous species will soon develop foliage. They did not lose moisture to evapotranspiration while dormant, but will when foliated. Of course, different types of vegetation demand different types of watering.

Soil texture and composition is also relevant to this increasing need for watering. Sandy soil drains well, but consequently needs more watering than denser soil. Organically rich soil retains moisture more effectively. Potted plants need frequent watering because their roots can not disperse very far. Hanging potted plants want even more frequent watering.

With so many variables, there are no simple formulas for determining watering rates. The process ultimately relies on diligent observation of the soil and vegetation involved. Soil, for many plants, should not remain too dry for too long. However, it should not remain too saturated either. Whether irrigation is automated or manual, it must adapt to the weather.

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Rain Will Increase Until Late Winter

The weather is about to change.

Defoliation is the colorful beginning. It indicates that the weather is getting progressively cooler. It then gets messy with the first rain. This is inevitable at this time of year. After all, it is late autumn. Storms will become more frequent as weather simultaneously becomes cooler. So, while gardens are getting wetter, they also take longer to dry between storms.

Ironically, vegetation uses much less moisture while it is so abundant. Deciduous foliage can not perform any evapotranspiration after it defoliates. Evergreen foliage is much less vascularly active while cool. Roots can not utilize all the moisture that autumn and winter rain provides. Soil in some areas might stay moist from now until next spring or summer.

Conversely, summery weather is innately arid and warm. That is how the Mediterranean climate here operates. Moisture is either scarce or abundant. Rain will eventually stop in spring, and then not resume until next autumn. Summer thundershowers are uncommon. Gardening could likely be easier with a bit less rain for winter, and a bit more for summer.

With more rain expected, irrigation needs seasonal adjustment. Such adjustments might need to be incremental, since weather changes incrementally. Manual irrigation might be either less frequent or less voluminous, or both. The same applies to automatic systems, which have a disabling ‘rain’ option. It turns irrigation off without modifying the schedule.

Besides necessitating modification of irrigation, rain can also be messy. It dislodges and accelerates the deterioration of defoliating deciduous foliage. It causes even formerly dry soil to become muddy. A bit too much rain can cause erosion. Cleaning up such mess is less pleasurable while the weather is wet and cool. Then, the weather gets messy again.

Rain can not postpone all gardening. Spring bulbs must get into their garden soil prior to winter chill. Dormant pruning happens later in winter, prior to spring. Fortunately though, gardening is less involved than it is during spring and summer. Maintenance of tools and sorting seed can be indoor tasks for rainy days. So is shopping online for seed, plants or garden tools.

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Pollen

For urban areas, the first rain of the season is typically icky. It mixes with all the crud and filth that has accumulated since the last rinsing rain of the previous spring. Damp roads smell like a mix of automotive fluids and wet tires. Asphalt roofs smell like tar. Even urban trees can initially smell like damp dust. It takes a while and a bit of rain for the crud and filth to rinse away.

This is the second rain of the season, and in a less than urban area. It does not smell objectionable, and is not notably cruddy. However, it still flows with an abundance of pollen that had not rinsed away already. Perhaps this pollen accumulated just since the previous rain, although not much has been blooming visibly at this time of year. It is impossible to say even what species dispersed so much pollen. Nonetheless, here it is, floating in the first few puddles to accumulate. Yuck!

It is no wonder that pollen is as effective at pollination as it is. It is impressively abundant and permeating. It is also no wonder that it is such a pervasive problem for those who are allergic to it.

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Watering Increases As Rain Decreases

Automated irrigation should help conserve water.

Rain is less abundant and less frequent now that winter has become spring. Humidity is decreasing. Temperatures are increasing. Moisture within both the soil and the air is less abundant than it had been. Irrigation that discontinued as the rainy season began should resume soon. Only supplemental watering compensates for the increasing lack of water.

Warmer and drier weather does more than simply deprive vegetation of natural moisture. It also accelerates new growth of formerly dormant or partially dormant vegetation. Such growth requires more moisture as it becomes less available. Increasing day lengths with intensifying sunlight enhance this need for watering. Although natural, it all seems ironic.

This recent need for watering is progressive. Rain still sometimes interrupts it, but will be less frequent as spring progresses. Rain will be very unlikely after later spring. Humidity will continue to decrease as temperatures continue to increase. Watering frequency and volume must increase accordingly. They might not begin to decrease until after summer.

Soil composition and texture also influence the increasing need for watering. Organically rich soils retain moisture more efficiently than sandy soils, for example. Gravely soils that drain well may necessitate frequent watering, even if less copious. Potted plants require frequent watering because they can not disperse roots. Hanging pots require even more.

Furthermore, different types of vegetation need different or specialized types of watering. Fibrous but shallow roots usually need frequent watering, even if they do not need much. Species with deep roots usually need watering less frequently. Some of them need more significant volumes of water than others. Some vegetation prefers only minimal watering.

With all these many variables, there are no simple formulas to determine watering rates. Manual irrigation is easiest to monitor, but is also tedious. Automated irrigation, although less tedious, requires more diligent monitoring. For any particular type of vegetation, soil should not remain too dry for too long. Also, vegetation should not exhibit any symptoms from desiccation.

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Fe

ICK!

Ferrum, which is abbreviated as “Fe”, is the chemical and element name of iron. It is apparently too abundant in this well water. Actually though, it is from the lining of the well. It accumulated because the pump has been inactive for so long. I am impressed that it functions at all after being idle for so long. I am concerned about the lining of the well, though. The hydrologic engineer tells me that I must superchlorinate the well to kill most of the iron oxidizing bacteria, and then flush the well by operating the pump for a long time. That all sounds like quite a bit of risky work. I do not like the concept of pouring something into a well that does not belong there. I am also concerned about what to do with the chlorinated water as it gets pumped out. I suppose that I could apply it to undesirable vegetation around the well. There will undoubtedly be a large volume of such water; but there is also a large amount of undesirable vegetation. I suppose that I could collect some or much of the water into an otherwise unusable tank to let the chlorine slowly volatilize from it. For now, until this superchlorination process begins, I suspect that this water is safe for irrigation. I do not mind if it leaves a temporary rusty residue that eventually rinses away. The water was even muckier before, and will get less mucky as more of it is used, so it could appear to be clean before superchlorination. Besides, I suspect that mucky water is less toxic to vegetation than superchlorinated water is. Because the rain stopped as suddenly as the rainy season began, and no rain is forecast for the next week, irrigation is now becoming a priority.

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Tornado

The tornado that stripped these redwoods landed right on Target. Notice the sign to the lower left.

The weather here may seem boring to those who are acquainted with other climates. It gets neither too warm nor too cold. Rain is limited to the relatively short rainy season. Humidity is minimal. Snow is so extremely rare that I can remember it only once in the Santa Clara Valley during my lifetime, and it was only half an inch deep. Tornadoes are about as rare, or at least they were. I can now remember two here, which is twice as many occurrences of snow that I can remember. Shortly after half past one last Saturday, rain, which had been falling for a while, suddenly became torrential, then instantly stopped, then instantly became torrential again. I stepped outside with Rhody to observe, and noticed Heather, Rhody’s feline ‘associate’ who prefers to stay inside during such stormy weather, had also come outside to observe, and was staring to the south. When I looked to see what she was looking at, I saw that not only were dark clouds speeding to the east, but that a portion of them was backtracking, as if swirling. My comment to Rhody and Heather was something like, “Well, at least tornadoes do not happen here.”. A few minutes later, a tornado did happen, right on Target, literally. It landed right on the Target store in Scotts Valley, less than two miles away. It was rated as an EF1 tornado, which apparently means that it was rather minor. It lasted for five minutes, though, while travelling only about a quarter of a mile. That is much slower than the clouds that we observed only a few minutes earlier. Fortunately, injuries were minimal, although a few cars were tossed. Utility cables, streetlamps and traffic signals were thrashed. So was much of the vegetation of the urban landscape.

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Precipitation Should Continue Through Winter

Red sky at morning, meteorological warning.

Deciduous foliage gets colorful with autumn chill. Then, it gets messy. Then, with a bit of precipitation, it gets even messier! It seems like a waste as it all succumbs to rain and, in other climates, snow. It is sensible, though. Deciduous vegetation will be less vulnerable to stormy weather without it. Weather will be getting increasingly stormy through autumn.

This is how the Mediterranean climate here operates. The dry season that begins during spring continues until autumn. The relatively shorter rainy season centers around winter. Therefore, most precipitation occurs during winter. Spring and autumn are brief transition seasons that tend to favor the dry season. Almost no precipitation occurs during summer.

Spring and autumn transitions between rainy and dry seasons are innately variable. The rainy season tends to finish early during spring, but may not. It sometimes pauses before resuming. It may do so more than once. Conversely, the rainy season tends to begin late during autumn, but may begin earlier. Occasionally, precipitation begins disturbingly late.

Generally, the first significant storm with significant precipitation begins the rainy season. This may be difficult to believe with typically significant time between the first few storms. Yet, with cooler weather, elevated humidity, and shorter daylength, moisture lasts longer. Precipitation, even if merely drizzling fog, will likely dampen gardens before they get dry.

Irrigation obviously does not need to be as generous as it was during summer. Until next spring, some vegetation will require none at all. Not only will weather provide and retain more moisture, but vegetation uses much less. Refraining from manual irrigation is easy. Adjustment of automated irrigation systems actually requires more effort and awareness.

As deciduous species defoliate for winter, some other species might get more vivacious. Cacti, agave, and some yuccas that lack irrigation become more turgid with precipitation. Remaining palo verde foliage is likely to become greener and fresher prior to defoliation. Most xeric species utilize moisture from precipitation as it becomes available seasonally.