University of Vermont
Department of Plant and Soil Science
CARING FOR CONTAINER GARDENS
Dr. Leonard Perry, Horticulture Professor
University of Vermont
Container gardens are increasingly popular for several reasons.
They’re an attractive way to add color to a patio, porch, or small
space. They satisfy the urge to garden if you have a green thumb but
have limited space in which to plant flowers, or even some edible plants.
Although easy to plant and to get a more instant effect, they do need
some care throughout the season to ensure healthy plants and continual
If the container plantings you made in spring are beginning to look a little
leggy, or the foliage is yellowing, or they’re not blooming, don't
despair. These and other problems are generally readily
fixed. Here's a list of common problems--and the solutions--to
help you get your container gardens back on the road to recovery:
Problem: You water regularly, but wilting still occurs. The probable
cause is poor drainage and aeration of soil. The solution is to repot using
a lighter soil mix containing more organic matter. Or, if that's not a
viable option, increase the number of drainage holes in the container.
Another possible cause is too many plants in the pot, taking up too much
water. You may need to repot, removing a few plants.
When repotting, add a water absorbing or soil moistening ingredient.
You can buy these at full service garden stores. They are generally
pellets that absorb many times their weight in water, releasing it and
keeping soils moist. They’re especially useful in clay pots or coir
(coconut husk) lined baskets that dry out quickly.
Problem: Plants are tall and spindly. The probable cause is too little
light, and perhaps too high nitrogen levels. The solution is to
move the containers to a location that receives more sun or light a day.
Stop fertilizing the plants, or decrease the amount.
Problem: Plants have stopped flowering. There may be several possible
causes. An end to its flowering may be natural for this variety.
However, if you planted annuals, deadheading (removing spent flowers) often
promotes branching and rebloom.
If the buds don't open, the cause could be disease and rots. Dig up a
plant; if roots are brown and not white, root rots are likely. Dispose
of infected plants and replant the container with fresh potting mix. Use one
made for pots, and not garden soil which usually has disease organisms and
doesn’t work well in containers. If tops appear to have disease, this
could be gray mold (botrytis). Give plenty of air movement around
plants to help dry leaves off, and don’t water late in the day so leaves
will be dry over night.
Too much fertilizer can cause excess leaf growth at the expense of flowers,
so fertilize less if the plant is lush but has no flowers. On the other
hand, if leaf growth looks fine and not excessive, plants may need more
fertilizer. Many of the new “vegetative” varieties (those grown from
cuttings and not seeds) need very high levels of fertility.
Problem: Yellowed foliage, especially the lower leaves. The probable
cause is too much water or too little fertilizer. If leaves yellow from the
bottom of the plant first, and plants lack vigor, it often means excess
water in the soil. If leaves are just generally a bit yellow overall,
this is likely from too little fertility. The solution would be to
water plants less often if the soil appears wet, and make sure the container
has adequate drainage. In addition to watering less, fertilize more,
especially if using low nutrition organic sources.
Problem: Edges of leaves are brittle and dry. The probable cause is
too much salt present in the soil, most likely from overfertilizing. (You
might notice a whitish crust on the soil surface or pot edge, another sign
of excess salt.) Moving containers quickly from shade to more sun also may
be the cause. The solution, if from too much fertilizer, it to water
generously--until water pours out of the drainage holes--to cleanse the soil
and remove the salt. Avoid changing locations and light levels rapidly.
Problem: Leaf spots, powdery or rusty areas. Probable causes are low
temperature, inadequate phosphate, or disease. Solutions are to move the
container to a warmer location. Apply a fertilizer containing high phosphate
(the middle number of the three in the analysis), such as a plant starter
fertilizer. You also might try fungicides, although if the problem is
serious you probably will need to toss the plant. To help identify if a
disease, and if so which one, work with your local garden center or contact
your state master gardener network to help identify the pest. (For
Vermont it is www.uvm.edu/mastergardener).
Problem: Foliage is riddled with small holes. The probable cause is insect
pests. Again, work with your garden center or local master gardeners to
identify the pest. Solutions are to apply the least toxic insecticide
that will do the job, following the instructions on the label carefully. If
the pest problem isn’t serious, you and the plants may be able to tolerate
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