Calvin R. Finch, Ph.D., Conservation Manager, San Antonio Water System,
and Horticulturist
Week of July 8, 2002

Q:        How close to the house can we plant a shade tree without it being a threat to the foundation?

 

A:        Most trees, even when they are very close to the house, do not injure the foundation.  I would, however, not plant a large shade tree closer than 10 feet.  Even the potential for damage is low overall; the closer that the tree is to the house, the more potential problems from branches rubbing and roots lifting the foundation.

 

Q:        Is it time to pull the tomatoes?  Between spider mites and drought, my plants look pretty ratty.  When do we replant?

 

A:        Yes, pull the tomatoes now.  Replant in late July or early August for a fall crop.  I always plant Surefire in the fall for an early crop and Merced or Celebrity for a later crop.  Sometimes the later tomatoes must be harvested green if a freeze threatens.

 

Q:        I planted Fanick’s phlox as you recommended.  The fragrance does resemble lilac.  The quality that you did not emphasize enough was the value as a cut flower; placed in a shallow bowl of water, they last for over a week.

 

A:        I agree, they are a great cut flower.

 

Q:        Our phalaenopsis orchids are looking terrible.  They have a sticky substance all over the leaves and are wilting.  I didn’t see any insects, is it disease?

 

A:        Look closely for bumps on the leaves and stems.  They are brown and hard to detect.  The culprit is in fact an insect called scale.  Scale insects live in protective shells (the brown bumps) and suck the juices from the orchid.  The sticky substance is honeydew, excrement common where sucking insects are feeding.  You can scrape most of the scale off with your thumbnail.  They can also be suffocated by applying horticultural oil diluted as per the instructions.  The orchids should recover.

 

Q:        If you only had room for one hummingbird plant on the patio, what would it be?

 

A:        I would select firebush.  Combined with a sugar water feeder, it will bring the birds onto the patio.  Zinnias, pentas and lantanas are also good.