Can you tell me something about the perennial called Heliopsis? Does it grow well in Baltimore?
The plant you are referring to, Heliopsis helianthoides, is most commonly called false sunflower. You should have no problem growing it here. It is native to most of the East and Midwest and can be seen growing along roadsides, open fields and other natural areas. It can also make a fine garden plant. False sunflower grows to about 4 feet tall and, true to its name, produces bright yellow ray flowers from mid-summer into fall.
If you are purchasing for a natural area, I would recommend that you buy the species plant. However, if you are purchasing plants for your home garden, you should consider one of the cultivars. 'Summer Sun' is widely available and produces golden yellow flowers on compact 2 1/2 - to 3-foot-tall plants. 'Prairie Sunset' is a new cultivar for the back of the flower border. It has golden-orange flowers on 6-foot stems from June to August. For variety, you might try 'Loraine Sunshine'; it produces golden yellow flowers atop bushy 30-inch plants with white / green-variegated foliage.
False sunflower grows best in full sun and average garden soil.
I have had difficulty getting clematis vine established in my yard. What is the key to getting it started?
Clematis has a reputation for being difficult to establish, but this is not really true. Here are a few suggestions.
First, be patient. Clematis vines take two full growing seasons to get fully established. You will be delighted in later years. Most growers agree that clematis likes neutral soil (pH 7.0), so I would start by doing a soil test. If your soil pH is too low, you will need to add lime to your planting mix.
Second, pick an appropriate planting site. Clematis needs sunshine, but it also likes to have cool roots, so you should plant shallow-rooted perennials around the base to shade the clematis roots. Such perennials include veronica, candytuft and coral-bells. Dig a hole 2 feet deep and 2 feet to 3 feet wide. Use a planting mix that contains one-third compost or well-decomposed leaf mulch. Plant the crown 2 inches below the soil surface and cover it with a 2-inch layer of mulch.
1. When starting plants from seed, keep them moist but not wet. Wet soil can lead to diseases that kill seedlings.
2. Consider working vegetable plants into your landscape. Vegetables can add color while providing fresh, healthful produce.
Dennis Bishop is an urban horticulture educator for the Baltimore office of the Maryland Cooperative Extension Services. If you have a gardening or pest problem, you can call the Home and Garden Information Center hot line (Monday through Friday, 8 a.m. to 1 p.m.) at 800-342-2507. You can also e-mail questions, order publications and diagnose plant problems by visiting the Web site www.hgic.umd.edu.