Q: I planted some zinnia seeds in March in a container in my garden. They are only about three to five inches high. Will they ever grow and bloom? Are there ways I can help them? I used a good organic potting soil. The wildflower seed mixture I planted in April also is coming up slowly. Will they bloom this year?
A: This is a case of planting a warm-season annual before it is ready to grow. In March, the soil temperatures are still in the 40s and 50s, way too cold for a zinnia (or a sunflower, squash, bean, etc.) One common result is that seeds will rot, so you’re lucky to have them germinate. Warming soil temperatures should bring them along now, but as insurance, I would sow fresh seed now, and they will develop well in the coming month as the heat arrives. Keep the bed weeded.
Q: When is the proper time to prune a Hawthorn? It’s driving me crazy mowing under and around it.
A: Hawthorn is related to the apple tree, so I would give it its annual pruning at the same time, i.e. during winter dormancy. This will reduce the chance of suckering from stem wounds in the growing season. You might do some judicious removal of the lower branches to avoid the conflict with the mower or, better yet, create a generous bed around the tree and plant it with low-care ground covers.
Q: I planted two euonymus bushes in the front garden two weekends ago, and then discovered that instead of being in line with each other (on either side of a larger abelia), one is awkwardly set forward—I must have strayed a bit when making the hole. I’d like to move it this weekend, because it seems as though I should do this before it grows too much, right? Or will that damage it? I suppose I could also wait for them to grow and then prune them into a similar placement (it’s a matter of six inches or so). But it’s driving me a little crazy.
A: As your chiropractor will tell you, proper alignment is key. In two weekends, these plants will not have sent out many wandering roots; they are just getting over the shock of being transplanted. And even if you had planted them earlier in the spring, it would be fine to move the errant one, especially with all the rain we have had. One of the common mistakes of planting a tree or shrub is in setting it too low; this causes all kinds of problems. You may plant it at the right height, but then the soil underneath it settles, and it will sink sufficiently to harm the plant. This is why it’s best to measure the rootball depth before planting to avoid digging more than you need. The critical step is to set the crown of the plant,—where the stem flares out to the roots—an inch or two above grade. (And then keep mulch away from the stems.) Thus, resetting your shrub will be easy. Take the opportunity to check the crown height of the other one, too, and reset that if necessary. Don’t overwater the transplants. One good initial soaking should see it through a month or so, unless we enter a dry spell.
Q: Is it too late to start planting anything? The warm weather and sun have got me itching to put things in dirt. I’m still new to gardening.
A: You could still plant loads of annuals, especially in containers. You can sow seeds of zinnias, sunflowers and even nasturtium for a fall show. In the veggie garden, it’s not too late to sow seeds of squash, beans, soybeans, carrots, beets and basil. The year is yet young.
Q: We have some poison ivy in our yard. What’s the most effective way to get rid of it (other than “very carefully”)?
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A: As you say, carefully. Do wear long-sleeve shirts, long pants and proper footwear (flip-flops in a working garden drive me up a tree). Be mindful, have a towel handy to wipe the sweat away rather than use the gloved hand just in contact with the vine. Smaller vines can be grubbed out with a mattock. For larger ones, cut a section out of the stem a little above the ground, and use a brush to paint a systemic herbicide on both wounds.
Q: I have a Kousa dogwood in my front yard. I have planted all kinds of perennial plants and flowers at the base. Unfortunately, nothing seems to grow or last. I planted lavender there and another spot in my garden, but under the Kousa tree it never came back. Is there something I am doing wrong? Is there a perennial I can plan under it?
A: Kousa dogwoods tend to be low-branched and spreading, meaning there is little space and light beneath them for other plants to grow. Anything that has height and needs full sun, such as lavender, would not be my choice. I would evaluate the afternoon light conditions and select low-growing ground covers based on their light needs. If it’s a bit gloomy, you can pick from a load of pretty sedges.
Q: How can I find garden centers or nurseries as an alternative to big-box stores like Home Depot or Lowe’s?
A: Full-service garden centers are becoming rarer in urban cores. I have found that local plant sales by native plant societies and other groups, often sponsored by public botanical gardens, can be a good source of plants, especially ground covers. I was at the annual plant sale at the Virginia State Arboretum recently (near Winchester) and was astonished by the size and variety of the vendors. Definitely worth a visit next time.
Q: We live in an older house with a very long street frontage facing east, on a busy street, so when we moved in, we tried to screen the street with plantings. We put a hedge of Miscanthus sinensis and later planted a couple of Leyland cypresses and a couple of river birches. The birches do a great job once they’re leafed out, but the cypresses have now gotten thin and bare for several feet up from the ground, so we’ve essentially lost our screening. We need to keep the cypresses to block the streetlight that was installed several years ago, and we’re getting rid of the miscanthus, but what kind of evergreen can we plant that will do well in shade? A friend gave me starts of aucuba, which I understand thrives in shade, but the deer eat it. If it matters, the yard slopes down from the street to our house and there are no storm drains, so the soil tends to stay moist but not soggy.
A: There are some lovely holly trees that remain leafy down to the ground, I’m thinking of the Red Hollies that are now so popular. Burford would work. For a large one, try the Koehneana, lovely and insufficiently used.
Q: Everything in my garden is coming into bloom now, which is great. Except it makes me worry that nothing will be blooming in August. Do you have recommendations for what I can plant now to fill a gap in blossoms in mid-to-late summer?
A: The obvious choice is long-flowering annuals such as petunias, calibrachoas and zinnias. For perennials, you could plant hardy hibiscus in wet areas, Japanese anemones (always seem to bloom earlier than you think) and hardy begonias. One of the best range of late-summer bloomers is the salvia or sage; some are hardy, some not.