June

Indoors

  • Cuttings can be taken of poinsettias and rooted in sharp sand, vermiculite, or perlite. Avoid drafts and maintain a fairly high humidity.
  • House plants can be moved outdoors to a partially shaded section of the patio, porch, or garden for the summer.
  • White callas indoors need a rest of about three months. Reduce watering and lay the pots on their sides.
  • Plants that could stand a south window in February or March usually must be moved to an east or west window for the summer.

Outdoors

  • Spring-flowering bulbs are now done blooming and the leaves may have already turned yellow and died down. Daffodils, hyacinths, and most small bulbs are normally left in the soil for the summer. Tulips are often dug up and stored in a cool, dry place (not a garage which may get too hot).
  • Newly set-out plants and seedlings should be shaded for several days until they are adjusted to the weather.
  • Container grown vegetables require large pots (14-inch or 20-inch) with drainage holes.  Use a great potting material with at least 25 percent composted bark or coir.  Add a time released fertilizer and apply a liquid fertilizer weekly.  Water containers daily until water runs out the bottom of the pot.
  • Crabgrass seedlings may begin to appear in the lawn if no pre-emergence killer was used.  Treat it now with any good post-emergence killer following the directions on the label.
  • When cutting peony blooms, leave some foliage on the base of the stalk to provide food for next year’s bloom.
  • Portulaca, an old-fashioned favorite, may be seed sown now.
  • Asparagus should not be cut after late June. Apply a liberal top dressing of a balanced fertilizer or compost to the bed.
  • Tomato plants may be supported by hoops or tied to stakes as they grow.
  • Plant additional gladiolus corms to provide late season flowers.
  • Plant seeds of endive, broccoli, and kale around mid-month for a crop of greens in the fall. Lettuce should be shaded from the hot sun and given plenty of water.
  • Plant sweet potato slips early in the month.
  • Sow seeds of beans, beets, carrots, kohlrabi, and turnips at month’s end for a late crop.
  • Sweet corn planted now will make rapid growth with another planting by mid-month.
  • Insect pests may visit your garden this month. Take time to learn which are beneficial before treating. If possible, control using nonchemical methods, such as handpicking, using sticky traps or introducing beneficial insects.
  • Also See: Integrated Pest Management for Vegetable Gardens
  • Invite beneficial insects to your garden with a mix of plants such as dill, fennel, parsley, tansy, sweet alyssum, daisies, coneflowers, sunflowers, and chamomile.
  • Prune deutzias, spiraeas, viburnums, pearlbushes, and weigelas as soon as blooming season is over, as well as Japanese quince.
  • Iris should be checked for signs of borers in the leaves. Cut and burn all leaves where found.
  • Mulching flowers and vegetables after the plants are growing will save time and labor, keeping weeds from sprouting and holding moisture in the soil. Any organic, weed free material will be beneficial – grass clippings, peat moss, leaves, hay, or straw.  Sawdust may be used if adding a source of nitrogen at the same time. Placing sheets of wet newspaper under the mulch will keep the weed seeds in the dark longer!
  • Perennial seeds can be sown in open seed beds or cold frames now.
  • Break off the old flower heads of rhododendrons, laurel, pieris, etc but without removing any of the branches. Next year’s buds are just under the old heads.
  • Pinch back chrysanthemums to keep them bushy.

Additional questions may be directed to the Master Gardeners at the Penn State Extension – Dauphin County – Hours: Monday, Wednesday, & Friday 9:00 a.m. – 1:00 p.m.

Where:

1451 Peters Mountain Road
Dauphin, PA 17018-9504
Directions to our office
Phone: 717-921-8803
Fax: 717-921-0135
DauphinExt@psu.edu