The DeKalb Extension Garden Patch

Some very interesting questions this week!

I have recently cleared an area of vinca and various weed trees. How do I keep them from coming back? How do I get rid of wisteria? - Cindy Smallwood

To keep weeds from coming back requires vigilance. Pull the weeds as you see them, and especially don’t let them go to seed. Keep areas mulched and/or install other plants to shade out competition. Weed species are very competitive, so make areas less suitable for their growth.

The best way to get rid of wisteria is to cut all woody vines and side shoots back to stumps and then treat the fresh cut stumps with a woody brush control herbicide such as Triclopyr. It is very difficult, if not impossible, to control these invasive climbing type vines unless you are willing to try some herbicides. Always read and follow all pesticide label directions and safety recommendations.  - Gary Peiffer, DeKalb County Extension Horticulture Agent

We have a 5 month old Bichon Frise/Coton de Tulear mix and we would like to put an agility course in our small, fenced in, (40’x40’) back yard for her but I’m stumped as to what would be the best, cleanest, easiest to maintain, toughest, groundcover to use. It would have to be something that she could run and jump on and hopefully not get her too dirty.  We’ve taken all the grass and weeds out of the back yard and we have down a hodge-podge of mulches at the moment … tree wood chips, pine straw, hay straw, which gets in her fur, and mini pine nuggets.  I was thinking maybe some sort of grass would work well but we only get sun from 11:00a – 4:00p with the yard in full sun maybe 3 hours a day but maybe there is a grass that would do well anyway … something low, thick and tough  -  Deb Wilson

Deb, You have the right idea with your mulches. No groundcover or grass will work well because they don’t take the wear and tear of daily foot traffic or dog urination.

You could try a mulching material that would have to be raked out every so often or consider installing a sandy area where manure could just be raked out, sort of like a giant kitty litter box. (How about a Japanese zen/sand garden?  -  looks attractive, but would be functional, too! - Averil)

The only grass I would consider trying would be Bermuda if you had enough sun for it and that is because it recovers well from damage. However, you would still often have large dead areas from compaction and dog excrement or urine. And from your question, it looks as though you probably don’t get enough sun for this.  -  Gary Peiffer

I have two hydrangeas.  One is very large with few blossoms and one is small with no blossoms.  Both get late afternoon sun. What can I do to encourage more blossoms?  When can I trim them back, especially the larger of the two?  How far can I cut back?  Do they need lots of water and fertilizer and if so how much and what kind.  Thanks.  - Lucy F.

Lucy, this is a great question.  There is a lot of confusion about hydrangeas because there are several different types, with different requirements.  Five types for the Atlanta area are Hydrangea macrophylla (bigleaf hydrangea, French hydrangea), Hydrangea quercifolia (Oakleaf hydrangea), Hydrangea paniculata ‘Grandiflora’ (Peegee hydrangea),  Hydrangea arborescens ‘Annabelle’ (Smooth hydrangea, Annabelle hydrangea), and the climbing hydrangea.  You really need to know which type of hydrangea you have before pruning.

Hydrangeas do very well with morning sun - in fact, they bloom best with three - four hours of direct sun, but hot afternoon sun will cause them to wilt.

Water well and plant them in organic well-drained soils, not clay areas.

Fertilize in spring and keep them mulched well to prevent summer drought stress.

You can find a lot of useful information in this UGA publication, “Hydrangea: A Southern Tradition” , at this site:  http://apps.caes.uga.edu/urbanag/index.cfm?storyid=2497

If you have questions for us, please email Averil at DeKalb Extension - abonsall@dekalbcountyga.gov. We will answer some in this column  and pass the others on to the Master Gardener desk - so everyone will get an answer! Alternatively, phone the Master Gardener desk - 404-298-4080.

Happy July 4th!