Horticulture Helpline FAQs

Frequently Asked Questions

 

Lewis Ginter Botanical Garden Librarian Janet Woody

Lewis Ginter Botanical Garden's Hort Helpline often receives questions from visitors on a wide range of subjects.  Janet Woody, the Garden's Librarian and a Virginia Certified Horticulturist (left), has answered some of our frequently asked questions about plants.

 

If you have a question for our Hort Helpline, you can contact us by phone or email. Phone: 804-262-9887 x240 or send email to: library@lewisginter.org

 

Q: I am digging a new flower bed and wonder if I can safely move daffodil and tulip bulbs? I have never done this before.

A:  Yes, you can move these bulbs.  Some say you should wait until the foliage turns brown, but it is OK to transplant with green foliage if you must.  Be sure to dig deep enough so as not to slice the bulbs with your shovel.  It’s better to bring up more soil than not enough.  The bulbs will easily shake loose of the soil.  You can plant them somewhere else, at the same depth.  Don’t remove any foliage as the bulb needs that to make food for next year’s flower.  This may be a good time to divide any bulbs where 2 or more bulbs are attached.  Separate gently and re-plant leaving space between bulbs so they can continue to make new ones.  If you do not want to plant your bulbs now, you can store them until fall and plant then.  Store the bulbs, with foliage, in a cool, dry, lowlight space, in a mesh bag or milk crate that allows air to circulate all around the bulbs.  While the bulbs would rather be in soil, they will be OK waiting until fall planting.  Tulips don’t always come back for return blooming, so don’t be alarmed if you get tulip foliage but no blooms.  You haven’t done anything wrong.


Q:
Someone gave me a beautiful amaryllis.  Can I make it come back next year?
A: Yes you can.  Once the bloom is no longer pretty, remove it from the flower stalk.  Once all the blooms are gone, cut the flower stalk 1 inch from the bulb.  Leave all the foliage alone; the bulb needs it to make food.  You can leave the flower stalk on and let it wither away, as it also sends food to the bulb.  Once night-time temperatures reach 60 degrees, you can set the pot outside, in a filtered-sun area.  Afternoon sun is too hot for an amaryllis, so make sure it isn’t getting too much sun.  Keep watering on the same schedule; winds and sun can dry out the soil faster, so you may need to increase watering.  Fertilize with a water-soluble houseplant fertilizer about once a week.  At the end of the summer, clip off yellowed or dried foliage, reduce watering and fertilizing, and let the bulb go dormant.  Store the potted bulb in a cool, dry area, around 50 to 55 degrees.  You can plant amaryllis in the ground for the summer; if you do this, place the bulb back in a pot for storage, or store the bare bulb in sand, or on a newspaper bed. Plan on a 2- to 3-month dormancy for your bulbs.  If you are keeping multiple bulbs, you can stagger their wake-up time to extend your bloom period.  Freshen up the soil around the top of the bulb, and check to make sure the bulb hasn’t grown too big for its pot; if so, repot it.  Give the bulb a good drink of water and place it in a sunny spot.  Stand back and watch the show begin.  A good book about amaryllis care in our library is: Amaryllis by Starr Ockenga, call number SB413.A5 O34 2002.

Q: When should I prune my roses?  I want to do it when your Garden prunes roses.
A: Roses are ready for pruning when leaf buds begin to swell and when the threat of a hard frost is over.  Here at the Garden we start early because we have so many to prune. Some people start when the forsythia blooms.  It’s hard to know how each winter will play out, so pay attention to the bud growth, what other plants are doing, and the weather report.
The goal of pruning is to remove dead or weak canes and to open up the center of the plant to improve air and light circulation.  Different kinds of roses will have different requirements, so it’s best to watch the plant for a year (to see, for example, if it blooms on old growth or new), and then figure out when to prune.  If you know what kind of rose you have, check in a rose care book for pruning guidelines.
General guidelines:  

  • Make your cuts at a 45-degree angle, about 1/4 inch above a bud that is facing toward the outside of the plant.
  • Use sharp by-pass pruners or loppers for thicker canes.
  • Remove all broken, dead, dying or diseased canes. Cut until the inside of the cane is white.
  • Remove any branches thinner than a pencil.
  • Remove sucker growth below the graft.  This growth may appear to be coming from the ground.
  • Remove any remaining foliage.
  • Pruning is good for roses, and bad pruning will be overcome by the rapid and hardy growth of roses, so don’t agonize.

Q: We moved into a house with rose bushes and some of them have a powdery substance on the leaves and the leaves are curling. What should we do? We know nothing about roses.  

A:  First, get a book about rose care.  You can check one out of the library (we have many at the Lora M. Robins Library!) or perhaps you should buy one as you may need to refer to it often.  Roses can be high maintenance.  What you are seeing on your roses is powdery mildew, a fungal disease and common ailment for roses as well as other plants such as phlox.  Go to a well-stocked plant store or nursery and ask an experienced person what kind of treatment you should buy for your problem, and then follow the instructions.  Powdery mildew is treatable.  To prevent outbreaks, make sure your roses have good air circulation all around, and that you water them at the root level and not on the foliage.  Your rose care book will help you determine proper care.  Roses require work but will give great satisfaction when filled with beautiful blooms.  And if you don’t like them, there are plenty of other shrubs for you to try.

Q: Why do people cut off their crape myrtles?  Should I do it too?  Does the Garden do this?
A:  Some horticulturists feel so strongly against the drastic pruning of crape myrtles that they call it "crape murder".  Pollarding is a pruning method that has been popular in Europe and the UK since Medieval times. It is a style that we don't practice here at Lewis Ginter Botanical Garden.  We prune crape myrtles occasionally, as needed, but not in an extreme way.  One reason that this technique is used is because the plant  may be getting too big for its location.  But by thinking ahead to  what the mature size of the tree, you can avoid this predicament. These days there are so many sizes of crape myrtles available to fit just about any location, so choosing the right size one, is the easiest solution.  If the crape myrtle no longer fits, you can remove it and place a smaller one there, or pick a different plant.
This kind of pruning leaves knobby scars, and results in many thin shoots coming from the cut location.  It doesn’t improve blooming, nor does it seem to hurt blooming.

 

Q: My Chinese evergreen has some yellow leaves, but otherwise looks healthy.  I have a grow light for it as it is in an area with no windows.  I water regularly.   What is wrong?
A: It’s hard to say for sure, but first, you might try at 20-20-20 soluble fertilizer.   Also, many houseplants suffer from a lack of humidity in our dry houses and offices.  It couldn't hurt to try misting it a couple of times per week with plain water and see if it improves.

 

Q: I want to give my friend a eucalyptus tree since she admired one at your Garden.  Where can I get one?
A: We do have some eucalyptus here at the Garden, but we know they have short lifespans as they are not hardy in our area.  If you can accept that it may not have a long lifespan, then go ahead and enjoy whatever time you have together.  Some people report some success in zone 7 with Eucalyptus gunnii or cider gum.  Here at the Garden we have a few Eucalyptus cinerea, or silver dollar eucalyptus.
Maybe your friend would like a small one for an indoor container?   Check with one of the larger local nurseries to see if they stock one of the Eucalyptus species.

The Hort Helpline will answer your gardening questions, or connect you with a source who can provide an answer. Library staff and volunteers respond to phone, email and in-person requests. Routine questions about pruning, growing conditions and propagation are usually answered the same day. Some complex questions and plant identifications may require more time. Persons requesting a plant identification can email digital photographs to library@lewisginter.org. Live specimens should be brought to the Library in a sealed plastic bag containing complete contact information for the requestor. Please do not bring diseased plant material to the garden. For all pest and disease questions please contact your local Virginia Cooperative Extension Service.

If you have a question for our Hort Helpline, you can contact us by phone or email.

Phone: 804-262-9887 x332
Email: library@lewisginter.org