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Master Gardener Articles

Posted on 03/15/2020
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Master Gardener Articles

Growing and Maintaining Beautiful Container Gardens

By Patty Bodwell, Master Gardener, Weld County

Gardening pictureAnyone can grow and maintain a beautiful container garden with a few simple tips on how to plant and maintain your garden.  To start you will need a container with a drain hole, soil, fertilizer, and plants.

Choose pots that are 8” or larger. Colorado is so dry that smaller pots will dry out way too quickly and you will have better success with larger pots. Plastic pots retain water longer. Terra Cotta pots breathe better and are good for those who overwater. Ceramic pots are nice but need to be taken in during the winter. Fiber pots are great for container gardens and are not decorative, but they are perfect to use in huge ceramic pots that would be very heavy filled with soil. Just plant your garden in the fiber pot and set it in the top of the ceramic pot and it will cover the unattractive fiber and the pot will be light enough to move around and store in the winter. Just remember to get the right size fiber pot that will rest in the top of your cover pot. If you want to get creative, use an old wheelbarrow for a portable garden or find other fun items to use for containers. Just make sure that they drain.

Use a good potting soil that does not contain wood or time release fertilizer. Your local garden center should have a nice selection of one or two brand soils that have lots of organic matter without wood or time release fertilizer in them.

Choose a grow fertilizer and a bloom fertilizer. These are two separate products. When buying fertilizer there are three numbers on the container. The first number is nitrogen which is what you want to use while the plants are growing (ex: 12-6-6). The second number is phosphorus and that is what helps plants bloom and you will start using this when blooms start to appear on the plants (ex: 5-10-5). Check your local garden center and there should be one or two good liquid fertilizer brands from which to choose. You will fertilize your plants every 7 to 10 days for larger and more beautiful plants and blooms. I prefer using two separate products instead of an all-in-one type or time release fertilizer because the fertilizer does not know the conditions or what the plants need at any given time. Too much nitrogen when plants start to bloom will cause your plants to start getting leggy.

Deadheading will be a big part of your success. A plant’s job is to reproduce and grow more seed. Spent blooms and dead stalks take energy away from the plant and new blooms so dead head your plants regularly to produce more and healthier blooms.

Got bugs? Get a 100% pure castile soap with peppermint oil in it. Mix a couple of drops in a spray bottle with water and spray any pests you see and underneath the leaves and that will take care of most pests like aphids and spider mites.

Choose a theme for your pot. Cool, warm, monochromatic, or complementary colors. Whatever you like is most important. Decide whether you want a shade pot or a sun pot. The right plant in the right place ensures more success. Most garden centers have their plants labeled for sun or shade. Sun is more than 6 hours of sun a day so choose plants based on where your pot will be placed. Most plants are labeled for a national audience so remember that in Colorado the sun is harsher than in other places. When in doubt ask your local nursery worker if it will be the right plant for the place you are putting your pot.

Choose thrillers, fillers, and spillers (I give credit to Rob Proctor who coined this phrase that has been used by many since he coined it). Thrillers can be one large plant that takes your breath away. I like to choose odd numbers so either one or three. It really depends on how big your pot is. Hot Wing Begonias, Geraniums, Spikes, Cannas, Grasses or Hydrangeas. Fillers are less tall and fill in around the thriller. They can bloom or be gorgeous variegated plants like Sun Coleus for lots of color. Spillers will be put around the edge of the pot to spill over the sides. Sweet Potato Vine, Wave Petunias, and vining plants. If fillers bloom, then the spillers may not bloom or vice versa.

If your plants have been nice and cozy in a greenhouse you will need to harden them off. Hot sun or cold could shock the plant if it has not been outside yet. Set your plants out in the sun for an hour or two the first day and then increase the time daily for 4 or 5 days. This will acclimate the plant to being outside in hot sun or cold nights. Remember to water them until it is time to plant them.  For more information, view PlantTalk.

Fill your pot with soil so when it is watered the water will not run off. Arrange your plants in the pot until you like the arrangement before you take them out of the growing pots. Turn the growing pot upside down and use gravity to get the plants out of the pots so you don’t pull the roots out or break the stem off trying to get it out of the pot. Scoop out the soil and put the plant firmly in place.

Water in your plants. Water until the water starts draining from the drain hole. There is no set schedule for watering. If it is summer and 80’s and 90’s you will most likely have to water every day. When it is this hot, missing one days watering could cause your pots to get too dry for the plants to take up water. This is usually the point of no return if they get too dry. You can use a moisture meter, or you can stick your finger about an inch or two into the soil to see if it is damp. As a rule, in the summer I usually water every day until water starts draining from the hole.

Every 7 to 10 days fertilize your plants. Your pots will need grow fertilizer until they start to bloom. Once they start to bloom you will switch to the bloom fertilizer. Fertilizing every 7 to 10 days will give your plants more blooms which will be healthier and bigger.

Deadhead your plants when the blooms are finished. This will ensure your plant has the energy to keep producing more and bigger blooms. Pinch or cut the blooms off underneath the seed pod. If you just pull the bloom out, for example petunias, you will leave the seed on the plant and that will take energy away from producing more and bigger blooms.

So, there you go. Steps for success. Plant in a good size pot, use good soil, water, fertilize every 7 to 10 days, and deadhead. Follow these steps and you will have beautiful pots all season long. Spring, Summer or Fall there are plants for your container garden to enjoy for each season.
These steps are also great for gardening herbs and vegetables in pots. If you plant tomatoes, make sure you use a 14” pot 8” to 12” deep. Tomatoes also like different fertilizer than flowers so check at your local garden center for products just for tomatoes. You can also plant peppers in pots 8” to 12” deep. Lettuce can be planted in a shallower bowl.

For more tips please visit CSU Container Gardens or Plant Talk Container Gardens.  To find almost any topic search for whatever you are looking for followed by (example: container gardening The CSU Extension has many great tips on many gardening topics to help you have gardening success.

Happy Container Gardening!

How to Manage Spring Frosts in Your Colorado Garden

By: Master Gardener, Lauren VandenBirge

Like many fellow Coloradans, I have been eagerly awaiting the arrival of Spring. I have been waiting for the trees to bud, the grass to green up, and to finally get some vegetables and flowers started in my garden.

And, like many in Colorado, I received a weather advisory on my phone about an impending frost advisory for the night. In true Colorado fashion, it was in the lower 70s today and it is expected to drop to between 32 and 35 degrees tonight where I live. And this is likely not the only time this spring season I will have to worry about my plants and a frost. Last year, the last frost in my area was close to the end of May.

I already have some plants in the ground and I want to make sure that they survive the frost. What do you do when a frost is going to hit your garden? How do you plan a garden that works best with the frost dates in your area?

  1. Find the average last frost date for your area. Plan what and when you plant in your garden around these dates. For the Greeley and Fort Collins area, you can reference this Climate Summary from Colorado State University.
    At the end of this document are the spring frost probabilities. You can use these dates to help plan for when you plant in your garden.
  2. Plant cool-season vegetables and flowers first. These plants are more likely to withstand a light or moderate frost and are ideally planted before the average last frost date in your area. Examples of cool-season flowers are pansies, snapdragons, and cool-season annuals. Vegetables are radishes, beets, carrots, broccoli, peas, and onions.
    For a more exhaustive list of cool-season vegetables and how to plant them, you can reference this document from Plant Talk Colorado.
  3. Wait until after the average last frost date to plant warm-season vegetables, like tomatoes, beans, melons, and squashes.
    The following Vegetable Planting Guide gives tips on when to plant, what temperatures are ideal, information on planting, and time to harvest.
  4. Lastly, if a frost is looming and you are worried about the plants you already have in the ground, there are many techniques you can use to keep your plants from freezing. Some of these techniques can add up to 18 to 30 degrees of frost protection! The main goal of these different techniques is to trap the heat the soil received from the sun during the day and use it as a heat source throughout the colder night. You can cover your plants with blankets, sheets, floating row covers, or plastic. Take care to keep the coverings dry and don’t let them touch the plants.
    For more detailed information, this document explains each type of frost protection, how to install it, and how much frost protection you can expect.

So, tonight, before it gets too cold, I am planning to head out to my garden and put in the plastic covered frames I built for the peas, onions, and radishes I have planted. Hopefully, in the morning, my plants will have survived the frost and will keep on growing!

For more information on spring frosts and freezes, please see Frost and Freeze and Spring Frosts and Snows.

Grow and Give: Plant a Garden and Support Your Community

COVID-19 has changed the daily habits of everyone, from where we work, to how much we drive, to how we stay healthy. One important change occurring in these times is how people access their food. Instead of running to the store to pick up a few things for dinner, we have to plan for a week or two at a time, bring our homemade masks and have hand sanitizer in the car. We have all seen the shelves: empty, gray and forlorn. COVID-19 has brought intense attention to the availability of food, where it comes from and how quickly supply levels change, which can leave us worried about the future.

But there is a course of action to remedy these feelings of distress and unease: growing and preserving your own food and giving the excess to others. Gardening and preserving increases food security for families, communities and nations because the food is grown hyperlocally, by people we trust.

Many of us have warm and safe memories of gardening with grandma and seeing her cupboard shelves lined with clear Mason jars, filled to the brim with pickled beets, green beans and raspberry jelly. There is a good reason for these wonderful memories. Food grown and preserved at home is affordable, accessible, nutritious and beautiful. One does not have to wait for the next shipment to arrive at the grocery store nor be dismayed by overpriced, tasteless tomatoes.

Gardens are also a clear demonstration of nature’s abundance, an abundance that can be given to neighbors and distributed to those in need. When food is shared with the community, we are all more connected, secure, involved and intertwined in each other’s’ lives. At the peak of summer, gardeners leave wildly shaped zucchini on friends’ doorsteps, homeowners stop passersby with offerings of cherry tomatoes, bursting with red juice and flavor. There are no losers when you grow your own food.

As a nation we already have a history of growing and sharing food to improve our collective wellbeing. During World War II, the United States government encouraged citizens at home to grow food in empty lots, unused spaces and containers in order to free up resources to meet the needs of the troops overseas. This emphasis on and expansion of local food systems increased from Maine to California, Detroit to Dallas, the Chesapeake Bay to the Puget Sound and came to be called the Victory Garden (for more about the history of Victory Gardens, watch a YouTube video, you will have to go to YouTube and google Victory Gardens.

The Victory Garden movement benefitted the war effort and everyone’s physical health, of course, but it also improved folks’ emotional wellbeing. Citizens on the home front were working towards a common goal, relying on each other, sharing food and knowledge, knitting together new relationships and cementing existing ones. Local food systems are powerful.

Right now, in another time of uncertainty, people from all walks of life can again strengthen their own sense of food security by creating and participating in a modern-day Victory Garden movement, which CSU Extension is supporting, called “Grow and Give”.

Whether you are new to gardening or you are a veteran gardener needing new knees from years of bending and shoveling, CSU Extension’s Grow and Give website offers a host of research based fact sheets on topics ranging from site planning to seed starting to how to harvest your bounty, all designed to support you in growing and preserving your own food.

Reach out to CSU Extension if you’d like to be a part of the “Grow and Give” movement. Or find a neighbor or friend with that knowledge and learn from them. Then, pass what you have learned on to others.

We can imagine a new common goal: safe, accessible, affordable and nutritious food for all, especially in these times of scarcity. We can make food uncertainty a thing of the past. Let’s Grow and Give. Grow a garden. Give your extra tomatoes and beans to your neighbors and grow beets and onions for your local food bank.

Feeling secure in your food source and feeling strongly connected to those around you is an unequivocal victory. There will always be an abundance when we grow our own food and grow enough to share with others.

Deanna Nagel, Colorado Master Gardener, April 2020

Book Review by Noel Johnston for Weld County, Colorado Master Gardeners

The Hidden Life of Trees

The Illustrated Edition

Written By Peter Wohlleben
Translated from the Original German by Jane Billinghurst

It has been said that the perfect gift is something you really want, but would never buy for yourself. Peter Wohlleben’s “The Hidden Life of Trees” precisely fits that definition. I love books (lifelong English teacher, you know), and this one isn’t particularly expensive, but I just don’t purchase books very often any more. So, my wife gave me this lovely volume, and another tree book that I will review when I finish it, for my 72nd birthday in March. Stunning photography, and very readable and informative prose make it easy to pick up for a quick 10 minute turn, or to immerse oneself in for two hours. I suppose a person could read the entire “Hidden Life” in less than three hours, but, just as a walk in the forest is an experience to be savored and not rushed, Wohlleben’s new edition is a delight to wander through at a leisurely pace. The large size (12” x 18” in hard cover) is ideal for a coffee table book, and looking at the pictures never gets old.

Wohlleben began his career as a forester working for a timber company. He says that when he started, he “knew as much about the hidden life of trees as a butcher knows about the emotional life of animals.” (p 1) When it came to trees, the only thing he cared about was their trunks and how fit they were for making top-notch lumber. Only after he quit his job for the timber company did he begin teaching forest survival training classes. He completed a project to allow survivors to bury their loved ones in a forest. His students and visitors often showed more interest in the bizarre shaped, gnarled and crooked trees than they did the more commercially viable ones, which ultimately led Wohlleben to appreciate those trees, too. As he writes at the end of his introduction, “I invite you to share with me the joys trees can bring us.” (p 2) This review will consist of “fun facts to know and tell” from each of the book’s six chapters.

Chapter One: The Forest as Community

Wohlleben believes that trees are social beings. They are connected in many ways. He cites University of Turin (Italy) researcher Massimo Maffei’s studies that conclude that trees “are perfectly capable of distinguishing their own roots from the roots of other species and even from the roots of related individuals.” (p 8) There are advantages (for trees) from working together, since a single tree is “not a forest.” (p 12) But, Wohlleben writes, that when trees combine forces to make a forest, they create an ecosystem that “moderates extremes of heat and cold,” as well as storing great quantities of water, and they allow each other to live to be very old. (p 12)

I was surprised to learn that the key way trees communicate is with scent, much the same as people do. Instead of perfumes and deodorants, trees use flowers, blossoms, and nectars to attract or repel insects, birds, large animals, and humans.

Trees also use scent to call for help when they are in trouble. Trees can match the precise saliva of an invasive insect, and send out aroma-based alarms that summon beneficial predators to devour those pests that are bothering it.

Wohlleben ends this chapter writing, “I suspect we would pay more attention to trees if we could establish beyond a doubt just how similar they are in many ways to (us).” (p 36) And I suspect that after being constantly amazed at the information in this chapter, I shall never again look at a tree the same way that I used to.

Chapter 2 - Life Lessons

In this section, Wohlleben expresses his belief that older trees, some of which he calls the “mothers,” actually pass their genetic legacies down to their “young.” These kids, so to speak, are like human kids, raring to grow and full of energy. Most species could easily grow as much as 18 inches per year. But, the author says, the mothers’ leaf canopies are so dense that in forests, only 3% of the available sunlight reaches the leaves of the young trees. This light deprivation, of course, limits the youngsters’ abilities to photosynthesize, putting them at a level just enough to keep from dying. Thus, the young trees are forced to mature slowly, which results in stronger and more sustainable growth, which, in turn, eventually allows the younger trees to grow into full scale (and sometimes very large) adult trees.

Because human lifespans average around 75-85 years in most places, we tend to think of a tree celebrating its 100th birthday as “really old.” This idea is reinforced because most trees intended for the lumber mill are cut down between 80 and 100 years old. Left to their own devices, however, trees can live hundreds of years, and some trees have been authenticated to be more than 1000 years old.

Fun fact: a mature beech tree sends more than 130 gallons of water a day through its branches and leaves. A good day for a human adult is 80 ounces. (p 51)

Amazing fact: Some research shows that trees actually scream when they are extremely stressed. The sounds are ultra-sonic, so humans cannot hear them, but Swiss scientists discovered that vibrations occur in the trunks of trees when the flow of water from the roots to the leaves is severely interrupted. (p 56)

Wohlleben postulates that these sounds are alarms sent by suffering trees to warn neighbors that water levels are dangerously low.

Chapter 3: The Delights of Decay

Wohlleben begins this chapter discussing aging, something which all living things do. A rather unpleasant factoid here: humans slough off ten billion skin cells per day. Ugh. Wohlleben then connects the idea of human (animal) skin to the bark of trees, both which, he says, “fulfill exactly the same function of protect(ing) sensitive inner organs from an aggressive outer world.” (p 64) And trees, the same as humans, shed a portion of their “skin” a bit every day.

Here’s a fact about aging trees that is eerily similar to homo sapiens. Every tree and human at some point stops growing taller. The tree’s vascular system (think veins and arteries) simply can no longer pump enough water and nutrients any higher. Instead of growing taller, trees do what many of us senior folk do: grow wider! Old trees and old people lose body mass, until one day, “it’s all over.” (p 68) In the case of trees, the young ones, who have been waiting for decades and decades, can finally burst up into full adulthood. For humans, perhaps a parallel is that Junior finally becomes the president of the company, or the Princess, at long last, becomes Queen.

Wohlleben comments in this chapter that the human need to cut down all the dead trees has led to worsening conditions for food and housing for many, many creatures, from birds to insects to fungi. He writes, “A dead trunk is as indispensable for the cycle of life in the forest as a live tree.” (p 78) Dead and fallen spruce trees, for instance, do particularly well as a “cradle” for the seeds of the next generation of spruce.

Chapter 4: Strategies for Survival

The first section of this chapter deals with winter survival. An interesting note here is that, unlike animals who hibernate (bears, most prominently), trees cannot grow “fatter” to prepare for winter,. So trees have to fill their tissues with food, and trees get “full” much more readily than bears. Trees must also use water, of course, and they cannot do that if the water is frozen.

Did you ever wonder why deciduous trees shed their leaves in winter, and conifers do not? Wohlleben writes that deciduous trees have much broader and fatter leaves than their coniferous relatives, and thus, they shed them to avoid the possible damage of critical force winter storms. (p 89). Compared to conifers, practically nothing happens to deciduous trees over the winter.

Wohlleben believes that trees can “tell time.” (p 98). They seem to know when to send out their buds and leaves, when to shed their fruit and their leaves. Like humans, trees sense warmth and increased daylight. Beeches do not start to bud out until there are at least 13 hours of sunlight per day, regardless of heat levels in the air. Do leaves “see,” Wohlleben asks? (p 98)

Oaks and beeches, among others, native to the Northern Hemisphere and its summer and winter cycles, quickly adapt to the reverse seasons in the Southern Hemisphere. Perhaps, the author says, trees have memories. (p 99)

Chapter 5: Out on a Limb

Wohlleben opens Chapter 5 with an interesting question: Why do giant redwoods in Europe never grow particularly tall (about half the height of redwoods in the Sierra Nevadas)? The answer meshes nicely with the Master Gardener motto “Right Plant. Right Place.”

Most European redwoods were brought there as gifts and trophies for royalty, nobility, and the rich.
They were planted in city parks and on huge estates. What is missing? “Relatives,” Wohlleben says. “They are, at 150 years old… only children, growing up far from home and without their parents and (friends).” (p 112)

European soil is vastly different from that in northern California. And the soil in parks is notoriously bad, hard packed from urbanization and foot traffic. “Right Plant. Right Place,” indeed.

Street trees, urban trees, are particularly susceptible to danger. Lack of water, smog, air pollution, dogs, compacted soil, paving of roads and sidewalks and building sites, salt and other winter treatments of icy roads, are also contributors. The author says that it is no surprise that summer storms topple a much higher percentage of urban trees than those in a forest under the same conditions. (p 121)

An interesting note here is that studies now indicate that trees, like humans and animals, actually need to ”sleep.” In 1981, the German journal Gartenamt reported that 4% of oak tree deaths in New York City happened because the trees were subjected to artificial light all night every night. (p 123)

One of the side effects of my Master Gardener training is that whenever I walk past urban trees, I see all the problems they are having, and can’t stop thinking about the mistakes that were made in their planting.

The garden notes listed below would be appropriate for the Chapter 5 section of my review, the chapter about “Right Plant Right Place” and the study of the differences in growth of Giant Redwoods in Northern California, contrasted with the same trees’ growth in Europe. #630, #631, and #632 seem particularly apt.

630 – Tree Planting: Right Plant Right Place


Chapter 6: Forest Benefits

Many, if not most, of the positive effects of trees are well known. Trees keep us cooler, they stabilize soil, the provide habitat for numberless species of animals and other plants, they filter the air, they provide beauty and they offer peace to the soul. So, it stands to reason that it is vital that we keep trees around, and “the older the tree, the more quickly it grows. If we want to use forests to combat climate change, we must allow them to grow old.” (p 133). Leaving forest alone to grow has become an increasingly difficult thing to do.

One study near Aachen, Germany, found that on a 98 degree summer day, the floor of a large deciduous forest (where the author is caretaker) was a full 50 degrees cooler than a similarly sized but thinned and trimmed coniferous plantation just two miles away. 50 degrees! (p 133)

The soil in intact forests is deep and rich, and becomes deeper each year, allowing for unparalleled opportunities for growth. Wohlleben claims that ”there are more life forms in a handful of forest soil than there are people on the (entire) planet, and a teaspoonful contains many miles of fungal filaments.” (p 141)

Wohlleben offers scientific data to support the idea that forests “make us feel better.” (p 151) For example, Korean scientists tested and tracked a group of older women when they were walking in forests and urban areas. What were the differences? At a nearly 100% rate, when these women walked in forests, their blood pressure, lung capacity, and elasticity of their arteries improved greatly. In the urban areas, none of these changes occurred.

But, in the end, he writes that without knowing any of the scientific studies, people simply breathe better, feel more rested and relaxed, feel stronger and steadier, and calmer and happier when they are amongst trees than when they are anywhere else. (p 154)

This uplifting and fact-filled book is a rejuvenating way to spend some indoor time. It’s even better read on the swing outdoors, or on the patio, or in the woods. Wohlleben ends his writing with this: “When you take your next walk in the forest, give free rein to your imagination. In many cases, what you imagine is not so far removed from reality after all!” (p 158)

Without hesitation, I recommend this book to tree enthusiasts and people who love nature. It would also be a great gift to folks who, at present, may not be particularly tuned into nature and the environment. Education is, after all, a wonderful thing.

I give “The Hidden Life of Trees” the Johnston 5-Leaf Rating.

Noel Johnston has lived in Greeley since 1976. After a 37-year career as a high school English and theater teacher, Noel has been a Master Gardener since 2017.

Growing Asparagus in the Home Garden Ruth Sens

The best time to plant asparagus was three years ago, the second best time is now. If you love fresh asparagus and want to try growing it in your home garden, this is the season in Northern Colorado to get started. In a few years of effort, you’ll be harvesting your own fresh asparagus spears.

Asparagus can be started from seed or by planting quality year-old crowns. You can buy crowns at your local garden center or order online. I bought locally so I could select crowns that had 8-10 large roots and a fat, healthy looking bud cluster. Seed should be started indoors in January for transplanting in late April. Jersey Giant, Jersey Knight, and Purple Passion are the varieties recommended for our area.

Because asparagus can produce for 10-15 years, choose a sunny (8 hours/day minimum) spot in your garden with well-drained soil where the plants will be able to grow undisturbed. Before planting, soak the crowns in warm water for 2-4 hours. Thoroughly work in four inches of well-composted organic material to a depth of twelve inches before planting – this extra effort will pay off in larger yields.

Now dig a trench that is 4-5 inches deep and place the asparagus crowns 12-18 inches apart in the trench by carefully spreading the roots out with the bud cluster facing up. Carefully back-fill the trench so the asparagus crowns are covered over with just 1-2 inches of soil at this point. CSU Extension cautions not to bury the crowns too deep in the Northern Colorado home garden as it can smother them. When the crowns start growing, slowly cover the shoots with soil each week until the trench is filled back up and level with the rest of the garden.

Do not harvest any spears for at least the first two years to allow the crowns and roots to develop fully. Some sources say to wait three years. At two or three years, you can harvest asparagus spears for 4-6 weeks in early May to mid-June.

Only harvest spears that are larger than a pencil. Do not over-harvest. Break off the spears or carefully cut with a knife below the soil level being careful to not cut other spears coming up. Then let the ferns grow until fall and stand through winter. Trim back in spring before new spears start appearing.

During the first two years, water 1-2 inches per week. Asparagus is a heavy feeder and benefits from fertilizer (10-16-8) in spring as the growth starts and again mid-summer after the harvest. Mulching around the plants with 2-3 inches of organic material will keep the soil moist, stop weed growth, and protect the plants in winter.

For more information and tips for asparagus planting, visit the CSU Extension Vegetable Garden Hints for Asparagus.