Tag Archives: citrus 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.

Fall Garden to-do’s for the Santa Cruz Mountains

Warm days, rainy days, short days, cold days- all in the fall of the year here in the Santa Cruz mountains. It's part of what makes our area so special to us. We are inspired by Mother Nature and our mountains. We feel a connection with nature as we enjoy our gardens. There are some easy things you can do at this time of year to extend that enjoyment. Gardening should be fun, too.

Taking cuttings of shrubs is a relatively easy and economical way to make new plants. Some plants that can be increased by hardwood cuttings include manzanita, coffeeberry, crape myrtle, pittosporum, euonymous, forsythia, spirea, viburnum and roses.  Edible plants like currants, figs, grapes and quinces also make good subjects.  

For deciduous plants it's best to take cuttings soon after the shrub drops leaves and the plant goes dormant. Evergreen shrub cuttings can be taken now. Start by taking cuttings of year old wood that's about a quarter inch in diameter.  Discard the top couple of inches of each stem since this unripened wood doesn't have enough stored nutrients to survive.  Cut the stems into 6-9 inch pieces.  Because a cutting won't grow if planted upside down, make the top cut at a slant, so you can keep track of it.  Then dip the bottom ends in rooting hormone and tap off any excess.  

You can store cuttings from dormant shrubs bundled and labeled in boxes of sand in the garage or outdoors in a well-drained trench. Each will form a callus at the base where roots will form next spring.  Come spring , plant the cuttings in good soil in shade with only the top bud exposed. Water as needed and once the new plants develop leaves and increase in size, start feeding them monthly with a balanced fertilizer. By next fall your new shrubs should be well established and ready to be moved to their permanent place in the landscape.

Some plants like abelia and spice bush are propagated by softwood cuttings in June. You can check the UC Davis website http://rooting,ucdavis.edu for information on specific plants you might be interested in.

Also you can simply pin down a stem of a plant like manzanita by putting a rock on it so the soil makes contact. After a year or so you will have a new plant that you can dig up and move.  Other natives like ceanothus can be propagated in a peat and grit mix and will root in about 50 days if given bottom heat. Take these cuttings in January.

Stake trees.  Trunks with leaning tops or those planted in very windy areas need support.  To determine how high to place ties, move your hand up the trunk until the treetops straightens.  I usually allow the stake to reach up into the canopy a bit so that a wind gust doesn't snap off the trunk right at the base of the canopy.  Tie the tree to the stake loosely in several places.  Trees in containers are tied tightly to the the stake but those in the ground should have some wiggle room to stimulate the trunk to be stronger.  This is a good time to check existing tree stakes to make sure the ties aren't digging into the trunk and the stakes are large enough to support your tree. Remember to keep your tree staked only as long as needed and then remove the supports.

Hummingbirds still need a nectar source.  Don't take down your feeder in the fall.  Anna's hummingbirds live and breed in this area all year long.  They need your nectar more in the winter, when very little is in bloom.  Even a species like the Rufous benefits from access to a large nectar supply to stock up on before a long migration.   Keep your feeders up year-round and keep them clean.  

The recent rains will allow weed seeds to sprout which is just what you want if you're planning a wildflower meadow.  The most common mistake when planting wildflower seeds is not getting rid of the existing weed and grass seeds that are in the soil and will germinate along with the wildflowers. These fast-growing weeds smother the slower growing wildflowers. Take time to eliminate the competition. Get rid of existing weeds when they sprout by cultivating the soil to a depth of not more than 1 inch. Deeper cultivation exposes more weed seeds that will germinate along with the wildflower seeds.

Pick last roses and add alfalfa meal or pellets which will soak into ground and prepare them for next spring. Don't prune until the end of January.
 
Groom strawberries and mulch to deter slugs in winter.

To help protect citrus from frost damage, pull mulch back from below the canopy.  This allows the ground to absorb heat during the day and release it at night.  
 

May – Words of Wisdom

With each new season, we start fresh with high expectations for a bountiful harvest of vegetables and mouth-watering fruit,  fragrant flowers to pick for bouquets and healthy plants to attract beneficial insects to the garden. As the months pass it seems one problem after another crops up. Don't get discouraged, though. Most any condition or disease can be corrected with the right information. I get many emails from readers with some of the same problems that you might have. Here are a few recent inquiries.

 

GARDEN HOSES

One reader asked about the safety of her new hose. The label on the hose states not to drink from it and she is wondering if it's safe to use it to water her organic vegetable garden.

Most of us grew up drinking water from the hose and on a hot day we still do. But is it safe? A recent study by the Ecology Center, a nonprofit environmental organization based in Ann Arbor, Mich., that reviews consumer products addressed potentially hazardous chemicals in gardening tools. The group tested nearly 200 gardening products, including hoses and discovered some disturbing findings.

To illustrate how chemicals can migrate from harden hoses into water, the research team left a section of garden hose filled with water out in the sun for several days. When the water was tested it was found to exceed federal standards for safe drinking water for several chemicals- including 4 times the standard considered safe for phthalates, 18 times that for lead, and 20 times that for BPA, an organic compound banned from baby bottles.

Most garden hoses that are sold are still made of PVC which can leach unsafe levels of lead into water. There are safer options available, though. Food grade Ether-based polyurethane or natural rubber hoses are a better choice. Look for hoses with nickel or chrome-plated fittings as brass can also leach lead into water.

Plants don't generally absorb lead, unless there is a high concentration of it in the soil but who wants to take a chance? With any hose, even one labeled "drink-safe' let the water run until it's cold before you drink from it because bacteria can grow in warm standing water.

CITRUS ADVICE

Another reader asked what she should do for her Meyer lemon which has yellow leaves. I told her that the yellowing is due to insufficient nutrients. First, apply a fertilizer containing nitrogen. There is also a chance that iron, sulfur and magnesium could be in short supply. Look for these ingredients on fertilizer bags and apply as directed. Also don't overwater citrus. Let the plant dry 2" below the soil surface between deep waterings.

LAWN CARE

Lawns also need a deep watering to train roots to grow deep. When to water? One easy method is to walk on the lawn and check in an hour after stepping on it. If it hasn't rebounded the lawn needs water. Also leave grass clippings to decompose after mowing. You'll need to mow about once per week so the clippings are short and can decompose quickly.

RHODODENDRONS

When everyone's rhododendrons but yours are blooming what can you do?  This plant sets flower and leaf buds in late August or September so fertilizing regularly for the next few month is important. Also water deeply when the soil is dry 1-2" deep and mulch the soil around your plant to keep the roots cool and moist. Rhododendrons and azaleas are shallow rooted so don't work up the soil underneath.

Feel free to email your questions to me. I'm happy to help.