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Your Expert
Debbie D. Dillion
Urban Horticulturist
Loudoun Cooperative Extension
You may also find the answer already in this great Virginia Master Gardener Program page that has the 100 most commonly asked questions in five categories based on the information they have received.
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Why do my River Birch leaves turn yellow and shed during the hot months? Is it from lack of water? A protective measure?
Also, do Crape Myrtles need their spend flower pods pruned in the fall? I find that birds like to eat the seeds out of them in the winter.
Thanks!
Dear Lori,
River Birch, Betula nigra, as a defense mechanism will have interior leaves that will turn yellow and be shed in response to dry conditions during the summer. This dropping of leaves reduces the amount of water that the tree requires making it more tolerant to drought. Leaf spot (a fungal infection) can also cause interior leaves to yellow and drop in moist years. Heavy infestations of aphids could also cause yellowing and leaf drop, so inspect the leaves closely to rule that out. If you have aphids, you may also see sooty mold, a black sooty growth on the surface of the leaves that feeds on the honeydew secretions from the aphids. If you suspect this may be the problem you can bring a sample to the Master Gardener Volunteers at their Gardening Clinic at Lowe’s in Sterling, Saturday morning between 8 am and noon or you can contact (703-771-5150) or bring a sample to their Help Desk Office located in the Loudoun County Extension Office, 30 Catoctin Circle SE, Ste. B (Wahcovia Bank Building), Leesburg.
Crapemyrtle, Lagerstroemia indica, blooms on new growth, so no need to prune last year’s seed heads. New growth in the spring will for the most part cover what remains after winter or when the new growth begins you can prune off spent seedheads at that time. The dried flower heads provide winter interest and are used by wildlife.
Debbie D. Dillion
Urban Horticulturist/Master Gardener Volunteer Program Coordinator
Loudoun County Extension
30 Catoctin Circle, SE Suite B
Leesburg, VA 20175
Dear Debbie,
1. I would LOVE some recommendations on colorful blooming perennials that I could plant that wont attract bunnies/deer?
1a. Any thoughts on what I can use (now) that will naturally deter bunnies from eating my garden? This year my garden seems like an all-you-can-eat buffet for the bunnies.
2. Any advice on various trees or flowering perennials for boggy/swamp-ish areas?
3. I started a veggie/fruit garden and we have a fertilizer tank built into our irrigation system, but I am concerned about using fertilizer from the big box stores. Is there a natural-broad spectrum liquid fertilizer that I can use for my irrigation system that will provide the same results as a high nitrogen fertilizer (compound make up of 20-10-10 or 10-5-10) that will keep my grass green while feeding my new fruit/veggie plants?
TIA,
Erika
1. There are lots of lists out there of “deer resistant” plants, but if the deer are hungry enough they will eat anything. My experience with rabbits is that plants are more prone to damage when they are first planted and young.
For the rabbits you can use a repellent of some sort, but read the label as you may not be able to use them on food plants. You could brew your own hot pepper spray using hot pepper flakes, steep them as you would tea, then strain and spray on leaves of plants you want to protect. This will have to be reapplied after rain.
Here is a list I found online of plants “resistant” to rabbit and deer that may be helpful: http://www.jaredsgarden.com/resistant.html.
2. The Piedmont Environmental Council has an excellent guide called, The Common Wetland Plants of Northern Virginia’s Piedmont
A Field Guide. It has valuable information about wetlands in the Piedmont of Virginia and a list of plants that naturally grow in those conditions. You can find it at: http://www.pecva.org/anx/index.cfm/1,370,1498,-1,html. For a list of regional nurseries where you can purchase native plants go to the Virginia Native Plant Society webpage for a list of reputable nurseries who do not harvest plants from the wild: http://vnps.org/content/vnps-native-plant-nurseries-and-plant-sales.
3. If you have cool season turf such as a tall fescue you should not be fertilizing it during the summer months, as its active growth is done during spring and fall, so if your vegetable garden and lawn are on the same system, but not separated, I would not recommend fertilization by that method. It is natural for cool season turf to go dormant (brown out a little and slowed growth) during the hot summer months and the turf will be fine when cool weather and rain return. Vegetable fertilizer should be based on the crop being grown and a soil analysis. You can pick up a soil test kit (kit is free, cost for testing is $10) at the information desk at your local Loudoun County library or at the Extension Office (30 Catoctin Circle SE, Ste. B, Leesburg). If your irrigation system is segregated and you can just fertilize the vegetable garden then you will need a liquid formulation. I don’t know the availability of those types at the local garden center. A source for organic fertilizers in Virginia is: http://www.7springsfarm.com/catalog.html#General%20Purpose%20Fertilizers.
Debbie D. Dillion
Urban Horticulturist/Master Gardener Volunteer Program Coordinator
Loudoun County Extension
30 Catoctin Circle, SE Suite B
Leesburg, VA 20175
Dear Debbie,
I have big, beautiful hydrangea bushes next to my front walk. Unfortunately, they are starting to overtake it. How can I cut them back without harming the bush? Keep in mind, I have the exact opposite of a green thumb, so don't presume I know anything about anything!
Thanks,
Keri
Hydrangeas are one of my favorite plants as they bring up fond memories of those my grandmother had in her garden when I was a child. Timing for the pruning of hydrangeas is based on whether they form their flower buds on old wood (buds formed in late summer/fall before flowering the next growing season) or new wood (buds formed during the current growing/blooming season). So if you want to have the most flowers next season you need to know which kind you have in order to time your pruning appropriately. If you are not sure and can take a photo of the leaf and flower and send to me I can attempt to identify which type you have. If you are more concerned about the plant overtaking your sidewalk, you could go ahead and prune now (though do so soon as late summer growth may not harden off properly leading to winter damage) – taking a few of the offending stems off at ground level and then cutting others back to a bud pointing in the direction you want the growth to take or you could wait until late winter and do the same while the plant is dormant (late February-mid March would be my preferred time as you will avoid the possibility of winter damage) and you can see the structure of the plant better. It sounds like your plants are happy and healthy, but remember that if you continually have to prune a plant to keep it in bounds that it stresses the plant making it more prone to attack from insects and disease pests so monitor the plants. If you only have to prune every few years to maintain the plants in their place they should be fine.
Debbie D. Dillion
Urban Horticulturist/Master Gardener Volunteer Program Coordinator
Loudoun County Extension
30 Catoctin Circle, SE Suite B
Leesburg, Va. 20175