Question: I would like to have the Double Knockout Roses, but would like to train them to an upright tree type of form and keep them in large urns around my property. Would they over-winter in the urns in Zone 7, or would I have to transplant them during the winter?

Answer:  The easiest, most reliable tree rose is Polar Joy (previously called Northern Encore). Polar Joy is the most winter hardy tree rose of any and absolutely will winter over in Zone 7 (Hardy to Zone 4).

Double Knockout can be trained as a tree rose. But it is going to take a lot of pruning over a two year period to achieve a tree form and regular pruning thereafter to maintain the tree form.

Question:  I have two green mountain boxwoods that were just planted in September - when is the ideal time for a light trimming, and when and what product should I use as a plant food? I also have Liriope and Butterfly Bushes - should these be cut back to the ground and when? I am also thinking of taking out my Royal Burgundy Barberrys (only because they are deciduous) and replacing them with a compact colorful evergreen that likes full sun - would you recommend Heath or Heathers? (I have a small front garden). Thank you! I really enjoy your show and website and looking forward to attending the Maryland Home and Garden show as I do every year!

Answer: Trim the boxwoods in early April. Fertilize with Plant-tone and Kelp Meal as soon as the ground thaws and then again in late November. Boxwoods also benefit from an early spring top dressing of Chesapeake Blue Crab Compost.

Butterfly Bushes should be cut back to about a foot from the ground in mid to late March. Liriope should be cut to the ground at the same time. Winter Blooming Heaths (Erica carnea) are really great dwarf shrubs. I recommend them highly. In my experience, Heathers do not perform nearly as satisfactorily - especially over the long term.

Question: Hello America! Here comes a question from a garden center in Sweden. Can you please tell me the difference between Hydrangea 'Endless Summer' and Hydrangea 'Bailmer'?

The reason is that I have ordered 'Endless Summer' from Holland and their answer was, that they haven't heard of it and booked me for Hydrangea 'Bailmer' instead. Please help me out with my request.

Answer: 'Bailmer' and 'Endless Summer' are exactly the same Hydrangea. To increase their royalty rights protection, for legal reasons, plant introducers use both trademarks and plant patents. 'Endless Summer' is the trademarked varietal name used for marketing; 'Bailmer' is the patented varietal name. This hydrangea was introduced by Bailey Nurseries in Minnesota, hence the first four letters of the patent name. The practice of double naming is especially common with new patented roses. For example, the real (patent) name of the shrub rose marketed with the trademarked name Knockout is RADrazz.

Question: I have heard that you can use newspaper to cover the soil and prevent weeds. Does this really work?

Answer: In general the answer is yes. Newspaper will smother out many types of weeds before it decomposes in about six months. It will also prevent new ones from sprouting from seed because it prevents seed from making soil contact. Newspaper is least effective on large growing perennial weeds that can force their way through the newspaper and which have root systems that store lots of nutrients over an extended period. Examples are Polk and Canada thistle.

Proceed as follows:

Remove all of the existing mulch. Place 10-12 sheets of newspaper right on top of the soil in open areas between the plants. Use only black and white newspaper not the color section. Many people find that newspaper is easier to work with if you wet it first. Overlap the edges of all sides of the paper by about three inches. Make sure that your perennials and flower bulbs have sufficiently emerged from the ground so that you can work around them and not smother them. Finally cover the newspaper with two to three inches of tan bark mulch.

Question:  I listen to your radio show and I get your weekly newsletter. You often recommend seaweed and Kelp Meal. What is the difference between the two and why are they so good?

Answer:  The difference between seaweed and Kelp Meal can be a little bit confusing. Seaweed is a plant that grows in the ocean. When harvested, dried and ground, the resulting product is called Kelp Meal. When Kelp Meal is liquefied, in common usage, the resulting product goes back to carrying the "seaweed" name.

Seaweed is just about the fastest growing plant there is. Some seaweeds can grow twenty feet in a day. When harvested and cold processed, the growth hormones which cause the cells to divide and multiply so rapidly are retained. Seaweed is the only known source of these natural growth hormones.

Scientific studies have shown that when applied to garden plants, both seaweed and Kelp Meal cause root systems to enlarge and sometimes overcome fungus attack (root rot). They also cause the whole plant to grow bigger, increase blooming and fruiting, and create greater intensity of flower color and cell walls to thicken. The thicker cell walls make the foliage more resistant to insect and fungus damage as well as to summer heat and drought. This is especially true when seaweed is applied as a foliar spray, although there is some improvement in these foliage-related aspects when either seaweed or Kelp Meal is applied solely to the root system. In addition to its foliar benefits, applied to either the soil or foliage, liquid seaweed is faster acting, but not as long lasting, as Kelp Meal. The merits of seaweed were known as far back as the Ancient Greeks. Seaweed was used by the Europeans as early as the 12th century.

Seaweed and Kelp Meal are growth stimulators to be used in conjunction with fertilizers. Apply them on every plant in your garden (except the lawn) at the same time that you fertilize. Use Kelp Meal at half the fertilizer rate. For example, if you are applying a cup of fertilizer on a plant, use half a cup of Kelp Meal at the same time.