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Tips and Tricks from Master Gardeners Archived Discussion Room

Fairfax County, Virginia

Tips and Tricks from Master Gardeners

Did you know that Fairfax County has a robust volunteer Master Gardeners program? Now is prime time for planning and planting, and our volunteer master gardeners are here to help. Join them online Wednesday, April 19 at 11 a.m. to learn more about the program, how to become a volunteer and how to find gardening success with your own plot of land in the county.

Pamela Smith : Good Morning! We are Master Gardeners from Fairfax County and Green Spring Gardens here to answer your gardening questions. Spring is upon us and it's time to get outside and get our hands dirty! If we do not get a chance to answer your questions today, please go to the Master Gardener Help Line at 703-324-5369 or

Eduardo : I need to find a simple way to keep the weed off. Nothing fancy. I just want a nice, clean grass.

Pamela Smith : Since we cannot know what type of lawn you have or the sun exposure, we suggest you go to where you will find out about our Home Turf Program. For $30, a master gardener will visit your home and give you advice about your lawn. Remember, unless you have Astroturf, you will always have some weeds!

Jennifer : I have a grass question. I am pretty sure we have a major grub problem so we have huge spots of clay where we used to have lush grass. I get so many conflicting opinions of when to plant seed /fertilize /weed and feed/and or I need to k or not only when to do all that to get grass back but when do I put stuff down to kick the grubs (they are in every shovel of dirt and grass I dig in the lawn) and what do u recommend to get rid of them. I'd like my lush lawn back.

Pamela Smith : Hello Jennifer,
    If you have a sunny lawn, you can only renovate it in the fall. If it is a shady lawn, it can be renovated at any time during the year. Grubs can be large and numerous at this time of year and the only way to control them is with a product called Dylox. Read the label before applying!  We strongly suggest you apply for the Master Gardener Home Turf Program for only $30 at  for an unbiased opinion about your lawn. A master gardener will visit your home to assess the lawn as well as the soil and a recommendation will be made as to how to control the grubs and renovate the lawn.  

Anonymous User : Do we still have to wait until Mother's Day to plant annuals?

Pamela Smith : Hello,
  The average last frost date for our area is April 15 however, that is the average. Most annuals prefer a soil temperature over 60 degrees which can only be assured after May 1. There are some heat loving annuals such as tropicals (caladiums, New Guinea impatiens, elephant ears, etc.) that should not be planted until after Mother's Day.

Stuart : Is there a best time to trim back azaleas? I have some older plants that have gotten "leggy" and need to be trimmed back to fit in their space. They annually have wonderful blooms and I would hate to prune and prevent the blooms next year.

Pamela Smith : The best time to trim azaleas is after they finish blooming. Do not prune more than 1/3rd of the shrub this year and continue with 1/3rd for the next two years until they reach the shape you want. Remove dead or diseased branches immediately.

Zeke : How thick of a mulch layer is considered too much? I like to get new colored mulch each Spring for aesthetic purposes, but also worry if I'm limiting my garden.

Pamela Smith : Apply no more than 3 inches of mulch in the garden bed. If there is existing mulch, break the mulch up from the previous year and remove weeds before applying mulch. Do not allow mulch to touch your tree trunks nor to pile up next to the foundation of your house. Rodents and insects love to burrow in thick mulch! Mulch volcanos around trees are bad news for the tree.

Anonymous User : I have a raised bed garden. Do I till the soil and disrupt the complex soil structure underneath or should I leave it alone and add a new layer on top?

Pamela Smith : We are glad to hear that you are using raised beds. The answer to your question is also complex. There are varying opinions. You do not want to disrupt the structure of the soil. We suggest that you add more organic matter, such as leaf mulch, to the top 2-3 inches of soil and lightly "fluff" it .  This will add more nutrients to the soil and improve the soil structure. In addition, add leaf mulch in the fall.

Dwight S. : What is your favorite plant to plant this time of year and why?

Pamela Smith : Now that is a tough question! We have so many favorite plants! Since there are three of us here, we will each give our favorites:
Sue - I am a vegetable gardener and I am getting ready to transplant my tomatoes in mid May into my garden plot. Love those tomatoes!!

Carmine - I am a shade gardener. I love hostas so I'm always looking for new varieties of hostas. Luckily, I do not have a big deer problem.

Pam - where do I start? summer bulbs like dahlias and lillies for a summer show of color. Sunflowers!!! I love tall, mammoth sunflowers for the children and the birds and of course, large popsicle colored zinnias. Color, color and more color.

Pamela Smith : Thank you for joining us today. You can also get gardening advice at the various Master Gardener plant clinics held throughout the county at libraries and farmers markets. The Green Spring Master Gardeners also hold a plant clinic at Green Spring every Saturday from 9:30 am - 12:30 pm. Go to for more information.
Happy gardening!