Tag Archive | garlic mustard

UW-Extension Tips

We’re based in Wisconsin and can’t say enough good things about the expert help that is available to us through the University of Wisconsin – Extension. In a recent email to all Master Gardener members, there were two really good articles and I’m reproducing them here.

Expert’s Tip: 10 Tips for A Successful Tomato Container Garden

Ann Wied, Waukesha County UW-Extension Consumer Horticulture Educator

Not enough time or space for a garden?  Tomatoes grow great in containers. Here are a few tips to use yourself or share with others …

  1. Choose a compact, bush, or dwarf tomato variety. These tomatoes are often labeled at garden centers as “great for a container gardening”.
  2. Buy healthy, resistant varieties.  Choose varieties that are resistant to diseases prevalent to where you live.  Look for this information on the plant tag or garden catalog.
  3. Choose a container large enough to provide support for your tomato.
  4. Don’t rush to plant your tomato. Plant near the recommended planting date for your area. Even if you can protect the plants from frost and/or cold night air, cool temperatures can keep growth slow, cause nutrient deficiencies, and prevent fruit set. In addition, once fruits start to form, cold temperatures can cause the tomatoes to become deformed.
  5. Place the container in an area that has at least 4 hours of direct sunlight each day.
  6. Water your tomato plant whenever the top 2 to 3 inches of soil is dry. This may be every day or every other day if the weather is hot and dry.
  7. When you water, water until it drains through the bottom of the pot and don’t let the plant sit in excess water.
  8. Fertilize once a month throughout the growing season with a fertilizer labeled for vegetable plants.
  9. If the tomato gets too large or bushy, support it with a small cage or stake and/or prune out some branches.
  10. Monitor for disease and insect problems. If a disease occurs, remove and destroy infected leaves or the entire plant if the disease is severe.


Click here for a version (pdf) you can print and hand out to clients!

Expert’s Tip #2: Tips on preventing seed production when hand-pulling garlic mustard plants

Mark Renz; Associate Professor and Extension Specialist; University of Wisconsin-Madison

Ever wondered about these questions:


  • Is there a developmental stage where garlic mustard plants can create viable seed if pulled?
  • How does different disposal methods impact seed production?


I have summarized the results of research done on this topic (read the reference for all the details and their specific conclusions):

What stages can garlic mustard produce viable seeds when hand-pulled?

Plants were hand-pulled over three consecutive week sand separated into three phenological groups:

  1. flowering: < 5% of flowers developing into fruit
  2. early-fruiting: 40%-60%of flowers developing into fruit
  3. late-fruiting: > 95% flowers developing into fruit

Of these stages only the flowering stage didn’t produce any viable seed or seedlings the following year. While lots of variability existed with the later two stages, each of these produced viable seeds. Although this experiment was conducted atone site in one year other studies using phenology have found consistent results from year to year and site to site. Thus this is clear evidence to me that the flowering stage is a safe timing to not worry about seed production if plants are hand-pulled.

What is the best method to dispose of hand-pulled garlic mustard plants?

Three disposal treatments were evaluated where plants were left in field conditions for three weeks:

  1. left in a pile on the ground
  2. scattered on the ground
  3. hung over tree limbs

Results found that regardless of disposal method, similar viable seed and seedlings the following year were found. While these results are encouraging, they were conducted over one year in one location in Ohio. I would caution about over-interpreting this information as different environmental/physical conditions may alter the result.

Can second-year garlic mustard plants resprout from taproots if just shoots are removed?

Plants were cut at the soil surface at one of four phenological stages:

  1. budding: no flowers
  2. flowering: < 5% of flowers developing into fruit
  3. early-fruiting: 40%-60%of flowers developing into fruit
  4. late-fruiting: > 95% flowers developing into fruit

While some plant stages resprouted quickly from the first three timings (bud, flowering and early fruiting) no resprouting occurred with the late late-fruiting timing. Regardless of timing, all treatments did not result in the production of viable seed and plants did not survive the following year. Thus stage of shoot removal doesn’t appear to be that important, and while resprouting can occur it may not produce any viable seed. Similar to above I would caution about over-interpreting this information as lack of shoot resprouting could have been the result of site specific factors.

The big picture:

In summary, this research confirms that viable seed production can occur if hand-pulled after the flowering stage. If you are hand-pulling after this timeframe it is recommended to plan on some of the seeds being viable. Realize that while zero seed production is the goal, all treatments had large reductions in the production of viable seed (largest # of viable seeds per plant was < 20).

Consideration of the level of infestation should be included in the decision making process as well as this information. If hand-pulling plants in an area recently infested with few plants and limited to no garlic mustard seed bank I would recommend not taking any chances and bagging/removing plants if past the flowering stage. However, if the location has been infested for multiple years, a seed bank is likely present and I would be more willing to leave plants after flowering on site. A few additional viable seed won’t be the end of the world as repeated trips for multiple years will be needed regardless of the success in any one particular year.   


Chapman, JI, Cantino PD and McCarthy BC. 2012. Seed Production in Garlic Mustard (Alliaria petiolata) Prevented by Some Methods of Manual Removal. Natural Areas Journal Jul 2012 :Vol. 32, Issue 3, pg(s) 305-315.