After a cold, wet March, April is looking to have average temperatures and remain fairly damp! Fortunately, we avoided the heavy wet snows that besieged us last March, giving us a bit less cleanup for April. Hopefully, this winter allowed for some time to write or read our garden logs and commence indoor tasks, such as seeding. As the sun and warmth of April return, take a deep breath and prioritize what must be completed vs. what could be postponed for a day or two. Remember, gardening is our hobby and we do not need any more pressures or deadlines!
Things to do:
- Finish pruning roses, small trees, and cut back shrubs early in the month. For red and golden-stemmed dogwoods (Cornus sanguinea cultivars) and willows (Salix), depending upon the deer browse pressure, either 1/3 to 1/2 of the older stems can be cut back to 6–12″, or the entire plant can be cut to that height. Leaving some of the existing stems helps protect the young shoots from deer predation. Shrub roses can be cut in half to keep them from becoming overgrown, while the stems of hybrid tea roses should be cut down about 2/3, to a bud that is facing outward. Hydrangea arborescens cultivars can be cut back to 3″; Hydrangea paniculata cultivars can either be cut back severely to 12″ or pruned lightly, leaving a 3–4′ tall framework for new growth to emerge; Hydrangea macrophylla should be thinned with the oldest and most branched stems cut to the ground while Hydrangea quercifolia should simply be shaped. Due to the milder weather of late March, it is too late to renewal prune hollies or yews this month.
- Finish cutting back ornamental grasses and perennials.
- If you overwintered bananas outside (such as Musa basjoo), remove the insulating leaves and the surrounding wire cage.
- Divide grasses and perennials if necessary. Remember that the center portion of the plant is the oldest and least vigorous and should be discarded. The outer, more vigorous ring will yield at least 10 new plants, with 9 of those going to friends, a new garden, or a curbside sale!
- As soon as the early blooming bulbs (snowdrops, winter aconites, snowflakes, scilla) have finished blooming, the clumps can be dug, divided and moved about the garden, if so wished. These bulbs are much more successfully spread about in spring while still actively growing than when purchased as dormant bulbs in autumn. It is also more financially prudent!
- Continue potting up canna, banana, alocasia, and other tropical plants that were overwintered in the basement.
- Edge bedlines and compost the pieces of turf that have been removed.
- Finish thatching and raking lawns. Apply a pre-emergent crabgrass control to established lawns before or during forsythia bloom, if crabgrass was a severe problem last year.
- Apply fertilizer and lime to lawns and vegetable gardens as prescribed by soil test results.
- Apply corn meal gluten to flower beds as a weed pre-emergent and mild fertilizer.
- For the vegetable garden, finish sowing tomato, pepper, and eggplant seeds. Earlier seeded lettuce, swiss chard, broccoli, and cabbage seedlings can now be planted outside, especially under low tunnels.
- For tomatoes, if you sowed your seed in a tray and the first leaves or Cotyledons are now well developed, tease apart the seedlings and install the plants in individual cells. Tomato seedlings can be planted deep, since roots will develop along the entire stem, providing a stout and strong plant (see images above – before planting on the left, planted on the right).
- Resist the urge to turn over or work the soil of your vegetable garden if the soil is too moist. In fact, try not to even walk on the soil if possible. If you can make baseballs from the soil, it needs a few more days to drain.
- Early in April, for those in the South—later, for those more North—seed can be sown directly in the garden for beets, carrots, spinach, cilantro, lettuce, arugula, mustard greens, bok choy, peas, and turnips.
- It is still not too late to plant potatoes, since it has been cold and wet. Only use “seed” potatoes from a seed company and resist using potatoes that you have bought at a grocery store that are sprouting!
- Remove the winter greens from containers and plant bulbs, pansies, primroses, evergreen grasses, etc., for early spring color. At Rutgers Gardens, we often use Acorus gramineus ‘Ogon’, the Golden Sweetflag, as a chartreuse accent plant for spring containers! Also consider many varieties of lettuce and swiss chard, as they are also very attractive and mix well with pansies and primroses. Plus, you can harvest a meal right from your containers!