Planting Guide For Zone 7
   When Can I Plant My Peas, Broccoli, Cabbage

Benton and Franklin Counties are considered Zone 7  with an average last frost date of April 15th and first frost date of November 15th.  These dates will vary a week or two so it is important to watch the weather before planting.

Use your last and first frost dates to calculate your planting schedule.  For Kennewick, Each winter, on average, our risk of frost is from October 17 trough April 15.  You are almost certain that you will receive frost from November 1 through March 23. You are almost certain that you will not get frost from April 21 through October 2.  That gives you a frost-free growing season around 193 days.

Using the planting schedule below will help you get the most our of your garden.  Starting seeds indoors before your last frost date will give you a jump start on the growing season.  Knowing when to transplant seedlings outdoors will help to maximize your harvest.



What is that growing in the vegetable garden

Green Manure

The term “Green Manure” is to describe specific plant or crop varieties that are grown and turned into the soil to improve the soil quality. The plants are usually started in the fall are early spring and then cut and tilled into the soil before going to seed.  Some types are left in the ground for an extended period prior to tilling garden areas. It is called green manure because it adds significant amounts of organic matter and plant nutrients to the soil much the same as animal manures do.

We plant Pacific Gold mustard in the fall and it usually winters over and is tilled into the raised garden beds and other areas in the spring a week or two before planting. The reason we use mustard is that studies show that as the leaves are fractured that chemicals (glucosinolates) are released into the soil.  The chemicals act as a natural soil fumigant when the mustard is plowed under and help reduce certain disease and nematode problems especially for potatoes and garlic.

Another good green manure is called Groundhog Radish (there are many varieties). These varieties are bred specifically to form huge tap roots that can reach down into the soil to reclaim nitrogen. The roots also help with water infiltration and soil aeration. Planted in late summer or fall the radishes are left in the soil or turned under.  They are also referred to as a “no tillage radish”.  If left in the soil to die off in the winter and decay to contribute a nitrogen supply for spring planting.  Money times in our area they will still have to be tilled in the spring.

Master Gardener Project

Your donation will enable our Master Gardener program to improve your community. Master Gardeners of Benton and Franklin Counties supports gardening educational and research to support beautiful and productive gardens while enhancing mental and physical health.

Kennewick Housing Authority

Kennewick Housing Authority (KHA) has announced a project will create 16 tiny homes for homeless families with children, homeless veterans, and homeless people with disabilities.  The 1-acre development is on 13th Avenue — a block of Washington Street and a few blocks from the downtown Kennewick Red Apple. The micro homes will be a mix of studio to two-bedroom units, ranging from 300 square feet to 600 square feet.  Stratford Homes in Rathdrum, Idaho, is building the prefab units to be trucked in by March.

Master Gardeners have been in partnership with KHA for several years and have established gardens in all their housing projects: Sunny Slope Homes, Nueva Vista I and II, and Keewaydin Plaza. Master Gardeners supports KHA’s mission in developing and maintaining safe, affordable, quality housing that promotes healthy neighborhoods and inspires communities.  Having raised garden beds available for families saves money and allows more fresh produces for a nutrient enriched diet.  The garden beds further provide for an atmosphere for a healthy interaction with the families through a common goal and sharing of gardens.  Master Gardeners provide also provides seeds and transplants for the gardens.

The Master Gardener Foundation is looking for funding to support this effort. A $150 donation provides funding for one raised bed that can provide approximately 200 pounds of fresh produce.  We are assuming that 10 to 12 raised beds will be provided if sufficient funding is obtained.  Please help if you can.

tours and Seminars

A variety of free classes and tours held at the Demonstration Garden, throughout the year that are provided by WSU trained Master Gardeners.  Classes are start late spring usually go through early fall.  A tour can be arranged by calling (509) 735-3551. 


Demonstration Garden

How it all started
Please Donate to help maintain and improve