How do I decide what to plant in my yard?
There are three considerations: total hours of full sunlight, the plant’s purpose or function, and plant variety. Narrow your search to plants whose sunlight requirements match those in your location. If you want a full-season “planted screen” or green fence along an exposed perimeter, narrow it further to include only full-sun evergreen plants that retain their foliage year-round and provide the desired privacy. However, if your yard is already lined with one type of plant, like Thuja occidentalis (emerald green arborvitae shrub), exclude that and plant an alternative to add variety, enhancing the aesthetic, ecological resilience, and seasonal appeal. In this example, Ilex glabra (inkberry), Ilex verticillata (winterberry), or Rhododendron periclymenoides (wild azalea) are great native options.
When is the best time to plant perennials and annuals DC?
It’s best to plant perennials in early spring after the last threat of frost, and before the arrival of summer, so new roots can establish. Washington’s last spring frost falls in March/April. This year’s should be March 30, after which planting perennials is optimal.
Annuals follow a similar schedule, depending on plant type. Hardy cool-season annuals like Viola tricolor (pansies) can be planted as early as March. However, tender annuals like Helianthus annuus (sunflowers) are best planted in May or whenever soil temperatures consistently reach 60F.
Measure soil temperature with a probe thermometer for cooking if you don’t have a soil thermometer. Before planting, conduct a soil test–available to DC residents for free through the University of the District of Columbia (UDC)–to determine pH and nutrient availability. A pH range between 5.5 and 7 is ideal for nutrient absorption. Some plants prefer more acidic soil (lower pH) while others prefer more alkaline soil (higher pH).
For vegetables and herbs, when is the best time to plant?
For vegetables and herbs, the best time to plant depends on the type of plant and whether it’s a starter plant from the nursery or sown from seed.
There are two main types of crops: cool-season crops–Pisum sativum (sugar snap peas), Raphanus sativus (radishes), or Daucus carota (carrots)–and warm-season crops–Lycopersicon esculentum (tomato), Capsicum annuum (pepper), and Cucurbita pepo (squash).
For starter plants, cool-season crops can be planted earlier, starting in March or April, while warm-season crops should be planted starting in mid-April or when the soil temperature is consistently 60F.
Seed-grown crops can extend the growing season. Some crops can be sown indoors as early as February and transplanted outdoors after the last frost, while others are best sown directly outdoors. Exact seed-starting timelines vary by crop and are noted on their respective packets.
When growing crops from seed indoors, use a seed-starting heat mat, a grow light or bulb, and a clear dome or cover to ensure faster early germination and stronger plants. Be sure to transplant into nutrient-rich soil and add organic vegetable fertilizer.
How can I prepare my garden beds for spring?
In DC, USDA hardiness zones 7b and 8a, the spring season typically runs from March through May. To prepare existing beds, remove any dead or undesirable plant material and add it to the compost pile. Likewise, prune “new growth” blooming shrubs such as Hydrangea paniculata (pinacle, limelight or peegee hydrangea). Use garden rakes lightly aerate the soil without disrupting essential biology. In contrast, tilling garden beds generally does more damage than good. Then, apply a 2-inch layer of compost to the surface of your garden beds. For new gardens, sheet mulching the area with cardboard and wood chips, or adding layers of organic matter, can suppress weeds and build soil structure.
Want to learn more about gardening or spend time with people who like plants? For more information, go to the Capitol Hill Garden Club website at capitolhillgardenclub.org. Send your questions to capitolhillgardenclub@gmail.com.
