Leonard Perry, UVM Horticulturist
and Charlie Nardozzi, Garden Consultant
Proper planting of containers, sowing greens, and pruning woody perennials are some of the gardening activities for this month.
Container gardening remains a hot trend. When planting large
containers for the deck or patio, save on soil by creating a false
bottom. Most of the plants you'll use don't need more than about a
foot of soil depth for their roots, so put some empty plastic soda
or water bottles in the very bottom, then cover with landscape
fabric or a piece of cardboard cut to fit to keep the soil from
eroding. Plastic pots turned upside down also work, as do coarse
and inexpensive wood shavings. Some use those Styrofoam packing
“peanuts” (put in plastic bags so they’re easily handled and
Unless you have one large plant in a large pot, such as a tomato
(there are compact ones now for smaller containers), you’ll be
combining several plants. For large pots such as barrel halves,
think about a special plant for a “thriller”, others for
“fillers”, and finally some “spillers” cascading over the pot
sides. Examples might be an ornamental fountain grass or tall
purple salvia for thriller, petunias for fillers, and lantana or
blue fan flower for spillers.
If you’ve planted enough plants to fill the pot (allow room for
some growth when planting), roots will fill the soil by mid-season
and plants will need frequent watering. This is especially true
for hanging baskets, with both container and plants exposed to
drying wind. To keep plants from wilting and lessen your need to
water more than once every day or two, incorporate a
water-absorbing product (usually granules or beads) into the soil
when planting. These hold many times their weight in water,
releasing it over time to the plants.
Also, make sure containers have holes in the bottom so excess
water can drain. Otherwise, a waterlogged soil will rot the roots
and kill the plants. If your plants are wilted, but the soil is
really wet, check to see if the pot has drainage holes, and that
they are not plugged.
To get a head-start on fresh greens, sow seeds in a large,
shallow container. Keep the container outside during the day and
bring it in at night if the temperatures dip below freezing, or
protect it in a cold frame. A window box with colorful greens is
not only ornamental, but makes for easy picking and protection
from hungry rabbits.
Woody perennials differ in the way they should be cut back in
spring. If butterfly bush has died to the ground, cut the dead
stems to the ground. Otherwise just shorten them by about one
third. Cut back Russian sage, rue, and artemisias to about 8 to 12
inches from the ground. Don't prune lavender until new growth
appears, and then just shorten the stems by about one-third.
Heather should be lightly pruned to remove the old flowers and the
tips of the shoots, but don't cut back to brown wood, stay in the
green. Wait until rose shoots and leaves emerge to prune, in
order to know what stems died and which are living.
Return to Perry's Perennial Pages: Green Mountain Gardener Articles-- your reliable source of gardening information for over 50 years.