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Dividing Perennials -- You
can still divide most perennials as long as they're not
spring-bloomers and their foliage isn't any taller than several
inches. Divide them if they are getting crowded (reduced blooms,
floppy stems, a dead spot in the middle) or you simply want more
plants.
Frost Dates -- Plant
warm-season annual flowers, herbs, and vegetables (tomatoes,
peppers, basil, marigolds, petunias, and the like) as long as your
region's last frost date has passed. (It's as late as May 30 here
in the Tri-Cities and at higher elevations.)
- Those warm-season annuals
include plants for containers, pots, windowboxes, and
planters. Remove any cool-season flowers you may already have
there. Work in a slow-release fertilizer. If there are plants
overwintering in the container and you're keeping them, simply
work the slow-release fertilizer into the top inch or so of
soil.
- After the frost date, plant
tender summer bulbs outdoors, including glads, cannas,
dahlias, and tuberous begonias.
- You can still take advantage
of April's cooler temperatures to plant cool-season crops,
including seeds for radishes, peas, sweet peas, lettuces, and
other greens, and seedlings for broccoli, cauliflower, and
cabbage.
- Wait to plant seeds for corn,
green beans, squash, cucumbers, okra, melons, sweet potatoes,
and other heat-lovers until the soil has warmed to 60 degrees
F. That's warm enough for you to walk on it comfortably
barefoot, and is usually two weeks after your region's last
frost date.
Planting Bare-Root Trees,
Shrubs, and Roses -- Continue to plant bare-root trees and
shrubs as well as bare-root roses.
Planting Trees and Shrubs
-- You can also continue to plant container-grown trees, shrubs,
perennial herbs, groundcovers, and perennial flowers.
- April is a good time to aerate
your lawn. Most lawns should be aerated every two or three
years to alleviate compaction and reduce thatch. You'll need
to rent a machine that takes out plugs of soil or have a lawn
service do it. (As an alternative, fall is also a good time.)
- If you haven't already, reseed
a weak lawn this month.
Mulch Matters -- About the
time the tulips stop blooming, the soil has warmed up enough that
you can apply a layer of mulch on flower beds and around trees and
shrubs. It reduces weeds, conserves moisture, and prevents
disease. Great stuff!
Deadheading 101 --
Deadhead rhododendrons and azaleas by cutting or pinching off
spent flower trusses. This will neaten their appearance as well as
encourage future blooms. Deadhead other fading flowers too.
- Start fertilizing roses, which
are heavy feeders. Decide on which plan of attack you want.
Some gardeners feed every two weeks until August with a liquid
fertilizer. However, a lower-maintenance approach is to work a
slow-release fertilizer (or compost) in around the shrub
according to package directions, usually every 6 weeks or so.
Some rose fertilizers include a systemic pesticide, so you can
feed and prevent pests at the same time. However, these
pesticides can also kill butterflies and beneficial insects,
so beware.
- For mums, pinch off the last
inch or so of the branches until July to assure bushy,
well-flowering plants. While you're at it, cut back asters and
other tall, floppy, late-summer bloomers by about one-third
once they're a foot or so high. They'll be sturdier and flower
better.
Pruning Shrubs -- You can
prune your rhododendrons and azaleas after they're completely done
blooming. After bloom time is finished is the time to prune other
spring-blooming shrubs, too.
Pruning -- Finish up any
other pruning this month, with the exception of evergreens, which
can be pruned any time from now to late summer.
Composting 101 -- Your
compost heap can probably use a little spring TLC. Open it up or
tear it apart to get to the completely composted "black
gold" down at the bottom and work it into the soil as you
plant. Make sure remaining material is nicely chopped up or in
manageable pieces (try running over softer stuff with a lawn mower
equipped with a collection bag).
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