The hustle and bustle of the Holiday Season is finally upon us! December is off to a chilly and damp start, and with the continued storms, there is little worry for newly installed plants needing water. This is the time of year to properly prepare the garden for winter, as autumn truly bids farewell and the sub-freezing temperatures of winter are just around the corner. As time permits between the cooking and the shopping, continue your notes and ledgers. On behalf of all the staff of Rutgers Gardens, a very Happy and Merry Holidays to all!
Things to do:
- Finish removing leaves from lawn areas. If possible, shred the leaves with the lawn mower and add them to perennial or annual beds as mulch. The shredded leaves that remain in the turf are actually very beneficial for the turf.
- Many people think that the decaying leaves look unattractive and should be removed from beds around the home. However, the leaves, whether shredded or whole, are very important to our biosphere and should be used as mulch wherever possible!
- If you have water features or ponds, keep the leaf nets over the pond at least through month’s end or until prolonged subfreezing temperatures are predicted to keep out any leaves that are still blowing about.
- Decorate those containers or window boxes remaining outdoors for the winter. Evergreen boughs such as Yew, Pine, Hemlock, Southern Magnolia, fruited Holly, or Cherry Laurel can be pruned from the garden. For large pots, add containers of red stemmed Dogwoods (Cornus sericea or Cornus sanguinea) or Willow (Salix alba ‘Britzensis’) for their glowing red stems. Add some white painted birch stems, which many Garden Centers carry, in order to create an attractive winter container!
- If you have recently planted an evergreen, make certain that the soil remains moist in case we have several weeks without another rainfall. A 3–4” layer of mulch over the roots certainly helps to retain the moisture and will moderate the depth to which the soil will freeze.
- Rhododendrons, Holly, and other broadleaf evergreen shrubs that have been planted this fall will benefit from an application of an anti-desiccant spray. Apply during periods when the temperatures are above freezing for several hours.
- Finish cutting back those perennials which have little to no winter interest and have collapsed to the ground, especially around the base of newly planted trees. The debris acts as a veil for hungry mice during the winter.
- By the same token and wherever possible, leave the stems and seed heads of Black Eyed Susan (Rudbeckia), Cup Flower (Silphium), Purple Cone Flower (Echinacea) and similar flowers standing for the winter, since they provide food for the birds and overwintering habitat for native pollinators and beneficial insects!
- Finish digging up Canna and Banana tubers, letting the soil dry so it can be knocked off, and then wrap and store tubers in a cool basement.
- Finish gathering seed from various annuals that are not cultivars and which will come true from seed. Dry and place in labeled packets for sowing come spring!
- Remove the old foliage from Bearded Iris, since egg masses from the Iris Borer overwinter on this year’s (or when they emerge, the previous year’s) foliage.
- Consider edging bedlines if the ground is not frozen and time avails, as it will be one less item to consider come the spring! Do not dig the edge of the bed too deep, as lawnmower wheels are likely to fall into the trench and scalp the lawn.
- Pot up daffodils, tulips, or minor bulbs into shallow pots and place them in the back of an unheated garage for the winter. Water when the soil appears dry. As the shoots begin to appear in February, place them in a sunny but cool window (hopefully in the garage). They will provide nice early color on the kitchen table in March or for outdoor containers in March, April, and May.
- For Tea Roses, mulch the graft union with soil, leaves, or shredded bark after the soil has started to freeze. This will ensure that the named selection that has been budded onto a rootstock will not perish during the winter. It is often beneficial to partially prune Tea Roses back to reduce any potential wobbling due to winter winds. Complete the pruning come spring.
- Winterize lawn mowers and other gas-powered equipment. This entails cleaning or replacing the filters and amending the fuel with an additive that will prevent it from becoming more viscous and potentially blocking fuel lines next season.
- If there is access to composted or even fresh horse or cow manure, it can be spread now in the annual beds (not vegetable or perennial). Shredded leaves can be spread as mulch for vegetable gardens if there was not sufficient time to sow a cover crop, as it adds organic matter back into the soil.
- Evaluate the Garden to see if it is in need of additional December flowering or fruiting cheer! Plants like Mahonia x ‘Charity’ (above right, photo taken on November 23, 2019), Aster carolinianus, and Hamamelis virigniana are presently in full bud or bloom and Ilex verticillata is full of glorious red, yellow, or orange fruit, depending upon the cultivar!