All posts by Jan Nelson

I am a landscape designer and consultant in the Santa Cruz mountains in California. I write a weekly gardening column for the Press Banner newspaper. I am also a Calif. Advanced Certified Nursery Professional and managed The Plantworks Nursery in Ben Lomond, Ca. for 20 years.
Design trends

Phenology and You

Corsican hellebore are tough low water plants and a good ground cover under oaks.

Always on the look out for potential problems in my garden, I can use all the help I can get. Solutions are out there. One of my go-to websites that I use to diagnose those problems is UC Integrated Pest Management or http.//ipm.ucanr.edu. You can look up just about anything that may ail you in your garden. As a test, I went to the Plant problem diagnostic tool for Home Garden Turf and Landscape. Talk about a rabbit hole. I was on their site for hours looking up stuff. Try it. Your garden will thank you.

The daffodils are blooming. Will spring be early this year? When will I no longer need to worry about the danger of frost? How much is climate change affecting our natural world? We can all remember years when there was little rain in January and February and it feels like the Bahamas around here. Then there’s this year. The rainy season is upon us. But what are the plants around here doing? Leafing out early? How about those invasive plants around your yard? Look to phenology indicators to give you some insight.

Plants have adapted over millennia to their growing conditions. The abrupt differences due to changing climate forces plant to migrate or go extinct. When temperatures increase plants bloom earlier creating the potential for timing mismatch between pollinators and plants.

Phenology – not to be confused with phrenology which claims that bumps on the head predict mental traits – is the study of key seasonal changes in flowering times, emergence of insects and migration of birds from year to year. When do they occur each year? Phenology is a real science that has many applications. In farming and gardening, phenology is used chiefly for planting times and pest control. Predictions for fire season are based on factors pertaining to weather as well as plant growth. Certain plants give a cue, by blooming or leafing out, that it’s time for certain activities, such as sowing particular crops or insect emergence and pest control. Often the common denominator is the temperature.

Websites like USA National Phenology Network at http://www.usanpn.org/ offer lots of information on the subject. The US Global Change and Research Program released the first 14 indicators of climate change. Among these is the Start of Spring indicator on this website which reflects the accumulation of heat sufficient to initiate leafing and flowering in temperature sensitive plants. Your own observations via Nature’s Notebook will help contribute to this research.

Indicator plants are often used to look for a particular pest and manage it in its most vulnerable stages. They can also be used to time the planting of vegetables, apply fertilizer or prune. Here are some common garden plants and what they indicate:

When daffodils begin to bloom, sow peas.
When dandelions bloom, plant spinach, beets and carrots.
When lilac leaves are the size of a mouse’s ear, sow peas, lettuce and other cool-weather crops.
When lilacs are in full bloom, plant beans.
Once lilacs have faded, plants squash and cucumbers.
When apple trees shed their petals, sow corn.
When dogwoods are in full bloom, plant tomatoes, peppers and early corn.
When bearded iris are in bloom, plant peppers and eggplants.
When locust and spirea bloom, plant zinnia and marigolds.

When forsythia and crocus bloom, crabgrass is germinating. When this happens the soil temperature at a depth of 4 inches is 55 degrees. Treat with an organic pre-emergent.
When crocus bloom, prune roses and feed your lawn.
Mexican bean beetle larvae appear when foxglove flowers open.

Record your own observations. Another great site is National Sustainable Agriculture Information Service at http://attra.ncat.org. Sites like these can also help you design orchards for pollination and ripening sequence, design for bee forage plantings, design perennial flower beds and wildflower plantings as well as plantings to attract beneficial insects and enhance natural biological control. How cool is that?

Design trends

Tips for Planting Success

This Bush Clover,a deciduous shrub, attracts pollinators.

With our gardens coming to life at this time of year we are hopeful that each plant will achieve its full potential 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 went wrong. 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 makes a plant thrive or just mope along? And how can you plan when one source shows the plant’s size at 6 feet tall while another has that same plant as 8-12 ft tall and just as wide? What’s a gardener to do?

When designing a garden, I take into account the growing conditions such as soil type and fertility, winter low temperature, space and light. All plants need 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 can be harmful to your plant’s health.

Choosing the right plant for the right spot is another important factor. How do you determine how much light your garden has? In our area a good rule of thumb in deciding if your plant is getting enough or too much sun is to note how many hours of full sun, part sun or bright shade your area is receiving during the middle of the day. it’s not as important what”s going on during the winter but knowing the summer conditions is crucial. Too little light can make plants weak and leggy with few flowers or fruit. Too much sun for a particular plant and the foliage will burn.

Most plants enjoy morning or late afternoon sun. Winter conditions are not always as important as those of the summer. Then again if your area gets no winter sun and your soil is heavy clay, that sun-loving native plant might not survive. Sometimes it’s complicated. Sorry, but it’s true.

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.

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 in the form of top mulch will increase your soil’s fertility. Fresh wood chips can rob your soil of carbon and nitrogen a bit as they break down but they retain moisture and keep the soil cool. Compost is great. It’s a trade off.

Plant your new addition correctly. Dig the planting hole at least twice as wide as the container but no deeper than the depth of the root ball. You can loosen the soil around the planting hole even wider if it’s compacted. Leaving the bottom of the hole undisturbed helps prevents the plant from settling too deep .Planting a bit higher than the surrounding soil also allows for a 2 inch thick layer of mulch. Don’t bury the crown of the plant and keep mulch away from the stem or trunk. In soils containing a high percentage of clay, score the sides of the planting hole with a shovel to aid root growth outward.

It’s best not to add fertilizers directly to the planting hole.Wait until new growth is several inches long before applying fertilizer. If you’re planting in very heavy or sandy soil you might amend the soil but current research has shown that trees, shrubs and perennials do not benefit from soil amendments. Because their roots quickly outgrow the planting hole anyway amended soil could hold too much moisture and rot new roots or the plant roots will just stay within the amended planting hole and not grow wider.
After planting don’t till the soil again allowing the beneficial organisms to re-establish.

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

Design trends

Allergy Season in the Santa Cruz Mts.

Don’t blame the acacia for your runny nose.

I live on Boulder Creek where the native red alder is in full bloom. Their catkins release wind-borne pollen which along with the redwoods wreak havoc for my friends with seasonal allergies. According to Pollen.com the allergy alert today is medium high. Birches and juniper are also releasing lots of wind-borne pollen. It’s going to be a bad day for those with allergies.

It’s the mating season for redwoods. Redwood pollen is dispersed by the wind. Strong winds blow the yellow redwood “flowers”, which are actually the flowers of the male cone, to release their pollen. Unfortunately because redwoods live in such a narrow band of coast line, there is no allergy shot for those highly affected by them. Pollen.com predicts pollen levels will increase as alder, juniper and birch release their pollen. Then come the oaks and sycamores.

About 25-30 popular landscape plants are responsible for the majority of plant-related allergies in California. During the height of the pollen season- from late February to June- there are often thousands of pollen grains in every cubic meter of air. One can breathe hundreds of them with every breath. Though pollens can travel many miles, the majority tend to stay in the general area of their origin.

Yes, the acacia trees are in full bloom. Being one of the first flowering trees we see they get our attention. Blooming acacias are often blamed as the cause of allergic reactions at this time of year but acacias are largely pollinated by insects and their heavy pollen doesn’t tend to become airborne. It’s the non-showy, quiet plants you have to watch out for. If you’re an allergy sufferer some plants are worse than others for you.

Redwoods, oaks, alders, ashes and other wind pollinated trees like olives, birch, box elder, cypress, elm, juniper, maple, fruitless mulberry, pine, walnut, willow and privet are the major source of spring pollen. Most native plants are good in the sneezeless landscape but if you have bad allergies or asthma it best to avoid wind-pollinated ceanothus, elderberry and coffeeberry.

Flower type is a good way to judge plants. The best looking flowers usually cause allergy sufferers the fewest problems. Plants with bright, showy flowers are usually pollinated by insects, rather than by the wind. These flowers produce less pollen and their pollen is larger and heavier, sticking to the insect rather than becoming airborne and lead to sneezing, a runny nose and watery eyes.

Some trees that are good for anti-allergy gardens are apple, cherry, dogwood, magnolia, pear and plum. Shrubs like azaleas, boxwood, lilac, Rose-of-Sharon, hydrangea and viburnum are also not likely to cause problems. Good flower choices include alyssum, begonia, clematis, columbine, bulbs like crocus, daffodil, hyacinth. Also good are dahlia, daisy, geranium, hosta, impatiens, iris, lily, pansy, petunia, phlox, roses, salvia, snapdragon, sunflower, verbena and zinnia. Lawns of perennial rye grass, blue grass and tall fescue blends are usually OK as they will not flower unless allowed to grow to 12 inches or higher. Bermuda grass, on the other hand, can pollinate when the lawn is very short, sometimes as quickly as a few days after mowing.

You may not be able to avoid those culprits growing on other properties but you can get the most out of your own backyard by creating a sneeze-less landscape. Replacing existing plants may be impractical but planning future plantings with these things in mind will save you a lot of headaches down the road and let you enjoy the sunshine outside in your garden.