Category Archives: gardening tips

Troubleshooting Plant Problems

Troubleshooting is a form of problem solving. And whether it’s a car problem, your smart phone, an irrigation system or yellowing leaves on a plant the goal is to solve it and make the product or process operational again. When you eliminate the potential causes of the problem hopefully the solution restores everything to its working order. Sounds like something Sherlock Holmes would say and it’s sometimes easier said than done as we all have experienced.

burned_heuchera_leaves
sunburned heauchera leaves

A few weeks ago I received a text with pictures of some plants with brown spots and asked what I thought might be the problem with their plants. This was after the heat wave we experienced and after asking a few questions about irrigation, location and how long the plants had been in the ground, I determined that the plant leaves had been burned in a pattern consistent with the location of the beating sun. At this time of year plants are growing wildly and need a good soak moistening the entire root zone. The solution: Better to water deeply less often than lightly which might not reach all the roots.

The subject of how much fertilizer and what kind came up in another troubleshooting email thread between some fellow horticulturalists. The issue was whether to use another round of organic high phosphate fertilizer in order to encourage bud development on a notoriously short-season tree dahlia. After some lively discussion we decided that the early spring application of rock phosphate was sufficient. Sometimes adding too much phosphorus may actually hurt a plant by preventing the uptake of other nutrients which must also be available to the plant in order to prevent unexpected deficiencies to appear. A balanced fertilizer containing all three nutrients- nitrogen, phosphorus and potassium-was recommended for the remainder of the season.

yellow_lemon_leaves
yellow leaves on lemon

Then there were some problems in my own garden. Well, it seems I am always trying to solve something with plants, pests or critters but this was with my lemon tree. At first I was perplexed when the older leaves of my lemon tree started turning yellow a couple months ago. The new growth looked fine so it wasn’t an iron deficiency where the young leaves display green veins along with the yellowish color.

It wasn’t a nitrogen deficiency either where the mature leaves slowly bleach to a mottled irregular green and yellow pattern, become entirely yellow and then are shed while the discoloration spreads to the younger leaves. I had fertilized in March with an all-purpose balanced fertilizer. Citrus are heavy feeders and require a steady source of nitrogen, the ideal citrus fertilizer having a ration of 3:1:1 (N:P:K)

After eliminating other mineral deficiencies or overwatering as the problem I decided that my lemon was simply dropping interior leaves which is normal after winter but I wanted to trouble shoot all potential causes to be sure citrus greening wasn’t the culprit. If it had been this deadly disease the leaves would have exhibited an asymmetrical pattern.

To quote Sherlock Holmes “Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.” I’ll try to remember that when I’m troubleshooting my next problem in the garden.

A Walk on the Wildside: The Ongoing Saga of the Hillbilly Gardener

rose_Fourth_of_July
Fourth of July roses

Many years ago I was invited by a Scotts Valley resident to visit their garden. This was no ordinary garden I was to learn during my visit and each spring I look forward to seeing what’s new at Doc Hencke’s garden. From his roots in Oklahoma and Texas he describes himself as the “Hillbilly Gardener” but with his extensive knowledge of trees, vines and just about anything that grows he is one of the most successful and enthusiastic horticulturists I know. I wore my walking shoes and we started talking about what changes he’s noted in his landscape the past few years of drought coupled with this winter’s rains.

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Straw bale veggie garden with Joe Ghio bearded iris

First stop- the straw bale veggie garden. The soil in this part of the garden is blue hard sub soil so this above-ground method of cultivation has been a real success. Richard told me that when the bales were first put in place a couple years ago he watered them thoroughly to start the fermentation process. Using a meat thermometer he determined by the internal temperature when fermentation was complete. He then soaked the bales with liquid organic fertilizer and applied some blood meal to augment nitrogen. The straw bales are decomposing each year but he’s going to use them once more this season. His crop of kale, lettuces and chard looked robust and happy.

Nearby a bed of Joe Ghio hybrid bearded iris were in full bloom. “It’s been a great year for iris”, Richard said. Not so good for peach leaf curl. The rains this winter set the perfect stage for the fungus to proliferate. He joked that the birds get the peaches anyway.

Richard is redoing his pond this year. He’s tired of fighting the raccoons and algae. Steeper sides will deter the raccoons and deeper water will help to prevent algae growth. He was forced to remove a curly willow that shed leaves into the pond as their natural salicylic acid was poisoning the pond.

succulent_collection
Succulent collection with blooming kangaroo paw

Last year a new succulent bed was planted along the back of the house and patio. His Sticks on Fire all died over the winter from the cold and rain but the aeonium ’Zwartkop’, echeveria ’Sunburst’, kangaroo paw and various sedums were filling in nicely.

weeping_leptospermum
Weeping leptospermun

Below the patio the golden Mexican marigold and blue Pride of Madeira were in full bloom along with a gorgeous stand of Weeping Leptospermum. “Magnificent this year, just look at this plant. Can you imagine what it’s going to look like in another 15 years?”, he said. Pointing out the visual boundaries he creates with flowering vines growing up into the trees, Richard observed that some are going better than others. Sound familiar in your own garden? Even this expert propagator is sometimes stymied by Mother Nature.

Richard_and_the_giant_ China_Doll
Richard and his giant China Doll tree

I love to hear Doc Hencke’s stories as he shows me around. Stopping at a China Doll houseplant that has now grown into a tree he tells me he thinks it’s one of the tallest specimens ever. His giant bird of paradise flower pod opened last week. I’d never seen their enormous blue, prehistoric-looking flowers before.

Richard’s new desert garden along the driveway is growing in nicely with the aloe plicatilis blooming for the first time. Also the yucca he and his brother dug up inTexas is finally blooming. “I’ve only waited 52 years for it”, he laughs.

There are so many stories that come with each and every plant in Richard’s collection. It’s always a walk on the wild side.

Pruning Roses- How, When & Why

 

Mixed rose bouquet
Mixed rose bouquet

In between storms I’m itching to get outside and do something in the garden. It’s too early to cut back the perennials as some frosty nights are sure to come our way between now and mid-March. But it’s just the right time to start pruning the roses. It’s best to prune your roses before they start leafing out or some of their energy will be wasted.

Last year, mine were looking just fine in January, thank you very much, so I thought I’d skip the pruning and removing last year’s leaves. Boy, what a mistake. Oh they looked great in January and February when there was no precipitation. Then some rain fell in March. I’m not kidding when I tell you that every single leaf got black spot and rust. My rose varieties are usually resistant to disease but they could not fight back against the fungal spores lurking in the soil just waiting to colonize those old leaves.

Yellow fragrant rose
Yellow fragrant rose

Roses give so much back I think they are worth the extra mulch and a little extra water to keep them producing those lovely blooms. There’s nothing quite as dramatic as a mixed bouquet of scented roses on the table.

I want my rose bushes to produce lots of roses on a compact shrub and not just a few exhibition size blooms so I prune my shrubs moderately. My goal is to keep the center of the plant open for good air circulation aiming for a vase-shaped bush with an open center. I’ll cut out canes that cross, saving the better of the two, prune spindly and diseased stems and dead wood. I’ll also prune canes that appear weak or broken. Healthy canes appear green or reddish while old and dying canes are brown. Then I’ll cut back the remaining stems by about third. When pruning cut canes at a 45-degree angle just above an outward facing leaf bud or a swelling on the cane. Slant the cut away from the bud to encourage growth outward. Clean pruners afterward to prevent the spread of disease and keep your pruners sharp to make clean cuts.

Same goes for climbing roses. Cut out extra stems if there are too many and also cut back long established canes to the place where they are slightly thicker than a pencil. Then cut each side stem down to several inches. This will cause the cane to flower along its complete length for a beautiful spring display.

Bouquet of mixed roses
Bouquet of mixed roses

Heirlooms roses such as David Austin, other old antique garden roses, and floribunda roses require less pruning because their open look is part of their charm. Keep this in mind and prune lightly. Old garden roses that bloom once in the spring should be pruned after flowering.

I got off easy this year as one of my roses was pruned and de-leafed by a deer who got inside the fence one night but the others are getting pruned the right way and at the right time. I know those old leaves will spread fungus spores and possibly infect the new growth so I’ll patiently pluck them off.  If you have a huge climber this might not be possible and spraying with fungicide may be your only option if you’ve had disease problems in the past. Rake up the debris beneath the plant and discard to eliminate overwintering fungus spores. It’s a good idea to spray the bare plant, coating the trunk, branches and twigs and the surrounding soil with a combination organic horticultural oil to smother overwintering insect eggs and a dormant spray like lime-sulfur or copper soap to kill fungus spores. If you usually only have problems with black spot you can use a mixture of 1 teaspoon baking soda with a few drops of light horticultural oil in 1 quart water and spray every 7 to 10 days during the spring.

Pruning intimidates some gardeners but when you understand the reasons for making the cuts pruning becomes less daunting. The reasons to prune are for health, appearance and to control size.

Prune your roses throughout the growing season, too. Deadheading or cutting off spent flowers encourages plants to re-bloom. Every time you cut a rose bloom to bring it indoors or deadhead a fading rose prune the stem down to shape the plant at the same time. Prune to a spot that has at least 5 leaflets. Roses grow from the point where they are cut so consider the overall shape of the plant as you snip.

Don’t worry whether you’re pruning job is perfect. Roses are super forgiving and you can always trim them up again later. Roses are like redwoods -you can’t kill one- they’re the energizer bunnies of the plant world.

Keeping Gardening Facts Straight

I’ve gotten several emails lately requesting more information about something mentioned in a recent column. I also received a phone call from a reader describing a bad encounter with a certain common plant. She wanted to share her experience so it didn’t wouldn’t happen to anybody else. And a conversation about how bad the poison oak is this year triggered a discussion about how to dispose of the stuff. So here goes. All the news that’s fit to print.

Whether it was Joe Friday who said it or Dan Akroyd in the Dragnet parody. we all want “Just the Facts, Ma’am“.

chipped_bark
ramial bark chips

In my column a couple weeks ago about garden planning for the drought, it was the last line “And don’t forget the… mulch (no shredded bark, please)” that caused a bit of confusion. It’s great that everyone has accepted the value of covering the soil with organic mulch. Organic mulches- such as bark chips, treated sawdust, straw or even grass clippings- keep plant roots cool, encourage earthworms and other beneficial organisms, conserve soil moisture, combat weed growth and protect the soil from erosion.

But is there an organic mulch that is better than another?

There are many types of mulch available. Nurseries sell different types of mulch in bags, building supply yards carry everything from bark nuggets in different sizes to treated sawdust to chipped bark and even shredded redwood bark. It’s the shredded redwood bark, also called gorilla hair, that does nothing for the health of your soil. If you have a very steep slope you may have to go with this type of mulch but that’s the only time I can recommend it. It will cling to a hillside without washing down in winter rains but treated sawdust would also work for this type of terrain and is much better for soil health.

Of all the types of organic mulches out there, recent studies have shown that ramial bark chips are one of the best mulches to improve soil health. Ramial chips come from trees and brush with branches up to about 3” in diameter with or without leaves. These chips contain a high percentage of thin young bark and young wood. This is what makes them so valuable to the garden. Young wood is a tree’s factory for producing protein, glucose, fructose, lignin and polysaccharides. It’s an important source of nutrients for living things at all levels according to a study by soil scientists, G.Lemieux and R.A.Lapointe. You can obtain these kind of chips free from tree trimming companies who are probably working nearby chipping roadside brush for PG&E.

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Euphorbia

About that call from a reader who had a terrible experience after pulling some plants in her yard that had gotten a little out of hand. She said she and her husband ended up with severe eye burn after getting some toxic sap from euphorbia in them. She said they really don’t know if some of sap became airborne while they were pulling stems or if they accidentally rubbed some near their eyes at some point in the day. They went to Urgent Care right away for treatment but the pain lasted for days. She described it as one of the most painful experiences she has ever had. Euphorbias are very deer resistant and drought tolerant and are being used more and more in gardens.

Many of us, me included, grow tropical milkweed or Asclepias curassavica to attract monarch butterflies. The milky sap from this plant protects the monarch from being eaten and can cause the same painful burning of the eye. I read of a case where a gardener’s clothes brushed some stems while she was tending the garden. Later she wiped the sweat out of her eyes and didn’t realize she had also touched her pants. She ended up with cornea burn causing temporary blindness and had to take strong pain relievers and steroids to elevate the pain.

poison_oak
Poison oak

Lastly, a fine crop of poison oak is growing this year so thick in places you can barely avoid it. The new foliage literally glistens with toxic oils. Many birds relish the white berries that form later in the season. 9 out of 10 people will get a rash if even one drop of urushiol oil touches the skin. And this oil has lasting power. It can stay active on any surface, including dead plants, for up to 5 years. Burning dead or dormant poison oak branches is especially dangerous as urushiol oils released in smoke can produce disastrous results if inhaled. So what to do with the stuff if you pull it out? Do not put it in your green waste can. It can end up being ground into mulch along with other green waste. Instead put it in your gray garbage can. Other plant matter that has to be put in the garbage can is pampas grass and bamboo. Don’t put them into green waste

So that’s the skinny on shredded redwood or gorilla hair, common plants with toxic sap and poison oak disposal. Be careful out there.

The Garden of Our Dreams vs The Real World

polygala_Petite_ButterflyWith our gardens coming to life at this time of year we are hopeful that each plant will achieve its full during this growing season. But that doesn’t always turn out to be the case and sometimes it’s hard to figure out what exactly is the problem. Growing plants isn’t an exact science. What works over at the neighbor’s yard doesn’t always apply to ours. What are the different factors that can make a plant thrives or just mope along? And how can you plan when one “reliable” plant source says the plant will get 6 ft tall an another shows that same plant as reaching 8-12 ft tall and just as wide?

When designing a garden whether it’s a client’s or my own I need to take lavender_West_Zayanteinto account the growing conditions such as soil type, nutrients, water requirements, high and low temperature, space and light. Most all plants use water to carry moisture and nutrients back and forth between the roots and leaves. Some need more water than others to do this but all have their own levels of tolerance. Too little or too much water or nutrients can be harmful to your plant’s progress.

Healthy soil provides an anchor for plant roots and helps support the plant in addition to providing nutrients. Healthy soil contains micro organisms and adding organic matter to your soil when you plant and in the form of mulch will increase your soil’s fertility.

Choosing the right plant for the right spot is another important factor but how can you determine if your garden has the right amount of sun or shade or moisture? In our area a good rule of thumb in deciding if your plant is getting enough or too much sun is to look up during the growing season and see how many hours of sun, part sun, bright shade or partial shade your area is receiving. To simplify, it’s not as important what is going on during the winter but knowing the summer conditions is crucial. Too little light can make plants weak and leggy looking with few flowers or fruit.

Allow enough space for your plant to grow. Plants can become stunted without enough room to grow and overcrowded plants often get diseased when air doesn’t freely flow between them. There’s a difference in a plant that just needs a little time to kick in and really start growing and one that is not thriving. Be patient.

Plant your new addition correctly. When digging the hole be sure that you loosen surrounding soil 2-3 times the width of the root ball. There is no rule that you can’t loosen the soil even wider around your planting hole. Use the shovel to loosen the edges of the hole so that it’s not hard and smooth. Roots have an easier time of growing out from the initial hole is sides aren’t hard as a rock. You can loosen the soil below the depth of the root ball if it’s really hard and amend it also. Be sure to firm the soil underneath the plant so the crown of your plant doesn’t sink below grade and drown during winter rains or watering. Planting a bit higher than the surrounding soil also allows for a 2” thick layer of mulch.

If you have a steep hillside, a super sunny or deep shade location or problem soil all the above tips are important for your planting success.

The November Garden

Cercis_Forest_PansyOutside my window, the Forest Pansy Redbud has started to display its spectacular burnt orange fall color. There’s a suet feeder hanging from the branches so I get to enjoy the antics of the Pygmy Nuthatches, Purple Finches and the Chestnut-backed Chickadees all day long as I watch the changing colors of the foliage. Out back I have a Catawba Crape Myrtle also starting to show fall color. Its leaves are turning a rich butterscotch shade which is lovely but not the reddish-orange described in the books. What causes fall color to vary from plant to plant? How does location in the garden, weather, climate and growing conditions affect what you see each fall?

The brilliant fall color we see in the leaves of trees and plants is always there. It’s just masked by Japanese_Maple-fall_color.1280chlorophyll during the growing season as the plant is busy making food while the sun shines during photosynthesis. Come autumn, shorter days and cooler temperatures cause the trees to switch into energy-storage mode, at which point their leaves stop producing chlorophyll. For the few weeks before the leave fall to the ground, they are colored only by their natural pigments. It’s these colors – red and purple anthocyanins and yellow and orange carotenoids that make fall foliage so glorious.

Some years the show is more dramatic than others. The best conditions for intense leaf color to develop are dry sunny days followed by cool, but not freezing nights. A warm, wet autumn will almost surely result in less-than-spectacular foliage because the process of chlorophyll loss will be less consistent. Freezing temperatures or winds meanwhile can cause leaves to drop suddenly denying them opportunity to enter their slow, colorful dormancy. Finally, trees that are under stress because of pests, disease, injury or drought may drop their leaves with no color change at all.

Japanese_Maple-fall_color2.1280So if your garden becomes shady early in the fall this may result in less vivid fall foliage. If your trees are stressed by drought like this year you may not get the usual colorful fall display. These and the above factors all affect the intensity of fall foliage colors.

Now is a good time to shop for plants and trees that can punch up the color of fall in your garden. Seeing your new addition in person will show you exactly what color you are going to get. Sure Autumn Gold Ginkgo will probably always color up bright yellow and Sango Kaku Japanese maples will show off their characteristic golden foliage but the fall color of Purple Smoke Bush, Katsura tree, Witch Hazel, Pomegranate, Oakleaf Hydrangea and Blueberry, to name just a few, can vary.

First Frost
I received an email from someone new to the area about when to expect our first frost. I’ve kept a weather Japanese_Maple_Sango-Kaku_fall_color.1600journal since 1992 and based on my records occasionally we get a light frost at the end of October. Mostly though, the earliest frost has occurred about second week of November with late November being the most common. Be prepared by moving frost tender plants under overhangs if possible or having frost blankets (not plastic) ready to cover delicate plants.

Transplanting in Fall
Need to move a plant or install plants out of containers and into the garden soil? Now through February offers the best time to do this. Soils are still warm at this time of year which helps new roots get established quicker than in later winter.

Prepare the new location first before excavating any plant. Dig a hole twice as wide as the rootball, but just the same depth. Use a sharp spade to make clean cuts through roots. Cut roots will form new, dense and healthy roots.

Before replanting, especially from a container, check for roots that have circled the interior of the pot. These must be tugged loose and straightened when planted. Don’t be shy about loosening roots. When replanting be certain to keep the rootball at the same level it was and don’t add soil over the rootball. Most plants need oxygen at the soil level.