Prepping your Vegetable Garden to Prevent Weeds

One of the biggest challenges to growing a vegetable garden in a non-raisedbed situation can be the weeds.  The can make the garden unsightly, compete with the vegetable plants you really want and make you feel  overwhelmed in trying to manage them.  Here is your five step plan to a better garden with fewer weeds:

Step one:  Control existing weeds.  If your garden has any weeds, you first need to take care of them prior to doing anything (except planning).  You have a couple of options.  You may rototill your garden to dig under existing weeds or you can spray out the garden with a non-selective herbicide such as glyphosate (Round-up).  You should do this well before you plan to plant.  This will only control the weeds that are there now and you will have more weeds germinate as the temperatures begin to warm up and water is applied. You may have to either manually take out any newly germinated weeds or spray just prior to planting.  Take care not to bring weed seeds up from lower soil layers by tilling too deeply. 

Step two:  Solarize your garden beds.  Soil solarization is a process that helps to control the weed seeds that are on or near the soil surface using the heat of the sun to “cook” the seeds and prevent germination.  Key elements of the process start with a soil that is fluffy, and very moist.  The prepared beds are covered and edges sealed with a clear 2-4 ml plastic for 4-6 weeks.  The heat energy of the sun is transmitted through the plastic into the soil and it will heat the soil sufficiently to kill many species of weed seeds.  It isn’t so great at controlling things like the large rhizomes of Johnson grass or nutsedge but can be a good way to moderate spotted spurge seeds.  For more information on the process of solarization go to:  http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74145.html

Step three:  Layout your irrigation system and plant.  Once your soil has been solarized you can layout your irrigation system.  Remember, wherever water is applied, that is where weeds will grow.  If you irrigate using a drip system, you can really reduce the number of weeds overall in your garden.    Once the irrigation system is in place and you have past the last frost date or planned for cold protection you can plant.  For ideas of what to plant when, go to our handy guide at:  http://ucanr.org/sites/gardenweb/files/29040.pdf

Step four:  Mulch.  One great tool to reduce weed problem is to use a mulch material over the planting beds

such as such as black plastic, white plastic (which is best for cool season crops planted in late summer). Brown Infrared Transmitting (IRT) plastic (great for heat to move into the soil better than black plastic but still blocks weeds), Red plastic (seems to increase yields in some crops) and Silver plastic (best as a deterrent to aphids).  You can also use compostable materials such as straw, and other coarsely ground organic materials or cardboard, old carpet or thick layes of newspaper.  The organic materials should be applied deeply enough to truly block weed growth-about 4-6 inches deep. 

Step five:  Grow a healthy garden.  A healthy, vigorous garden will be very competitive with any weeds that do germinate.  For information on how to do that, go to a PDF on Vegetable Garden Basics at:  http://anrcatalog.ucdavis.edu/pdf/8059.pdf