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Saturday, April 20, 2024

CSU Master Gardeners

Beckoning all gardeners to ‘spring’ into action

By: Khursheed Mama

In yards across Northern Colorado, the emergence of spring bulbs and new growth on trees and shrubs indicates the beginning of another growing season. While many gardeners are happy to have a break during the winter months, spring brings renewed enthusiasm for spending time in the yard. It’s a good time to harness this energy and attend to basic maintenance in the garden to ensure another season of beauty.

March and early April, before bud break, are still acceptable times to prune both deciduous and evergreen trees. For evergreen trees and shrubs, removing new growth provides a way to reduce plant size. While no more than 25% (10-15% in a drought year) of a tree should be pruned in any given year, removing crossing branches, sprouts, and dead wood will help promote tree health and minimize damage from wet heavy snows. For information on pruning methods, refer to CSU Extension Fact Sheet #7.003 on “Training and Pruning Fruit Trees” and the Colorado Master Gardener (CMG) Garden Notes #618 on Pruning Evergreens; both can be found at Summer and fall-blooming shrubs (e.g., potentilla, caryopteris, Russian sage, etc.) may be pruned at this time, but wait on spring-blooming shrubs like forsythia and lilac—pruning now will result in loss of flowers—prune after these plants have flowered. Additional information on pruning shrubs is available from CMG Garden Notes #619. Early April is an ideal time to remove dead wood from roses and shape them as desired.

In the absence of natural moisture, it is important to continue to deeply water trees and shrubs when weather conditions allow. If you live in an area with poor soils or known micronutrient deficiencies, spring is also a good time to add compost or slow release fertilizers and specific micronutrients to the garden. For more information, read Fact Sheet #7.235 on “Choosing a Soil Amendment”.  Mulching exposed soil in garden beds will help minimize the impact of foot traffic on root development and help reduce evaporative water loss.

This is also the time of year where ornamental grasses should be cut back and dead material removed from perennial plants to facilitate new growth. Make sure to allow spring-blooming bulb foliage to yellow before pruning it back—it helps replenish the bulb and store energy for the coming year. If you need a quick fix to draw attention away from the dying foliage, consider planting hardy pansies for a pop of spring color.

As soon as it is warm enough for irrigation systems to be turned on, check for leaks and efficiency. It will be especially important this year to minimize water loss with planned water restrictions (for lawns) in many Northern Colorado communities. The cities of Fort Collins and Loveland offer free irrigation audits to help optimize lawn watering throughout the growing season—check with your water district for more information.

Aerating the lawn in spring helps correct soil compaction and reduces thatch, encouraging water penetration and root growth (be sure to mark your sprinkler heads). The spring is also a good time to fertilize lawns; try to time application during periods of natural moisture. If you plan to use a pre-emergence herbicide to prevent crabgrass, it is best to do this by April 15th. Keep in mind that if you also plan to overseed your lawn, this should not be done concurrently as most pre-emergence herbicides will prevent seed germination, since they have a long soil residual.  For the best seed germination, soil temperatures should be consistently greater than 50 degrees F (ideally greater than 60 degrees F). If you need to reseed, but want to apply a crabgrass preventer, consider seeding in fall.

Cool spring temperatures favor certain vegetables including peas, onions, Brussels sprouts and broccoli to name a few. For specific details on when these can be planted, refer to CMG Garden Notes #720.

The spring tasks may seem daunting, but your garden will reward you all season long for your efforts. Enjoy this season of renewal and remember the CSU Extension Master Gardeners are available to home gardeners throughout the year to help answer gardening questions. Larimer County Master Gardeners are available on Mondays, Wednesdays and Fridays between the hours of 9am and 1pm from April 1st through October 30th, 2013.  Call them at 970-498-6000 or send them an email at


Gardening Tips:

By: Sandi Leffel

Start with the Basics: Know What’s in Your Soil

Did you know that 80% of landscape problems are related to soil conditions? Ever wondered how to improve the vitality of your garden or lawn? Testing your soil is an efficient way to guarantee success in your garden or turf.

Colorado State University offers a soil testing service which will determine which nutrients may be lacking in your soil. In addition, the test will also clearly state if there are nutrients that are too plentiful. The CSU soil testing lab offers a complete service which will analyze your soil, make management suggestions and recommend fertilizers and additives.

Soil is a dynamic living system. Well-managed soil is made up of 25% air, 25% water, 3% organic matter and 47% minerals. Plants need 17 elements for normal growth. Carbon, hydrogen and oxygen come from the water and air. Soil is the main source of all the other nutrients. The primary nutrients are nitrogen, potassium and phosphorous. They are used in large amounts by the plants, and if deficient, may be supplemented with fertilizers. Calcium, magnesium and sulfur are secondary nutrients and generally used in large amounts, but are usually readily available to the plants and in adequate supply. The remaining 8 elements are called micronutrients and only needed in small amounts: iron, zinc, manganese, molybdenum, boron, copper, cobalt and chlorine.

One of the most common soil problems here in Colorado is nitrogen. As with all nutrients, it is difficult to know if your nitrogen levels are appropriate without a soil test. Excessive nitrogen in the garden causes vegetable production and quality to suffer. Insects and disease may also contribute to crop failure with an excess of nitrogen.

Soil testing is an economical way to take the guess work out of gardening and lawn management. In order to maximize your growing potential, let the CSU soil testing lab guide you to optimum benefits. For a complete list of soil testing services, please visit


Gardening Q&As

By: Anne Wuerslin

Q:  My newly planted Scotch pine trees are brown at the tips and have some die back in the inner branches, what can I do?

A:  We are in the second year of extended drought and chances are your trees are suffering from desiccation and winter scald.  Evergreens tend to shed needles more rapidly if water isn’t  in sufficient amounts.  Fall, winter and early spring watering is critical for new trees, and you should try to deeply water at least every 3-4 weeks when daytime temperatures are 40 degrees or warmer.  Increase the frequency as temperatures rise. Conifers are best planted in the spring, when they can develop a good root system during the summer.  For more information on fall and winter watering, please refer to CSU Extension Fact Sheet #7.211 at  For care of trees and shrubs during drought, please refer to

Q:  What flowering annuals are good for children to start indoors?

A:  The seeds of nasturtiums, moon flower, and four o’clocks are big and easy to handle.  Nasturtiums come in many varieties and the flowers can be eaten.  Moon flowers bring scent to the night garden.  Old-fashioned four o’clocks open in late afternoon, tolerate poor soil and have a wonderful fragrance.

Q: I would like try different herbs rather than the usual parsley, rosemary and thyme, any suggestions?

A: Lovage (Levisticum officinale) is a tall leafy perennial whose leaves can be used in soups and salads.  The taste is similar to celery and the leaves of spring growth are best used early before they turn bitter. One lovage plant is usually enough for an herb garden.  For more information on growing herbs, refer to PlantTalk script #1003 at

The author has received training through Colorado State University Extension’s Master Gardener program and is a Master Gardener volunteer for Larimer County.

Larimer County is a county-based outreach of Colorado State University Extension providing information you can trust to deal with current issues in agriculture, horticulture, nutrition and food safety, 4-H, small acreage, money management and parenting.  For more information about CSU Extension in Larimer County, call (970) 498-6000 or visit

Looking for additional gardening information?  Check out the CSU Extension Horticulture Agent blog at for timely updates about gardening around the state.

Visit PlantTalk Colorado ™ for fast answers to your gardening questions!  PlantTalk is a cooperation between Colorado State University Extension, GreenCo and Denver Botanic Gardens.

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