Timing is everything. Here’s what to do now — and what not to do — in a Puget Sound garden
This time of year is a celebration of early blooming shrubs and perennials. This is a good week to visit a local nursery and fill your pots and planter boxes with primroses, pansies, heather and dianthus.
You can also prune dead and damaged branches from Japanese maples, but don’t get snippy with cold tender plants such as salvias, Rose of Sharon or hardy fuchsia. Pruning always stimulates growth, and tender plants that are still leafless are sleeping and dormant this month. Attacking them with the pruners will wake them from dormancy and then any new growth will be felled by frost.
Q. When should I plant shrubs such as lilac and viburnum? Also when is the best time to plant trees and roses? We are new to the area. — N.C., Enumclaw
A. Invest in a shovel and start planting. Any tree, shrub or perennial that you see for sale at our local nurseries now can be planted directly into the ground.
The advantage of adding new plants in March is that the ground is moist and the rains will continue, so you will need to worry less about watering your new plants. Always water around the root zone after planting, but don’t stomp on the soil as this will compact it too much around the roots. Instead, firm the soil with the heels of your hands, forming a basin to catch the rain water that will fall in the rest of the month.
Q. What is the best way to harden off new plants you get from the nursery? Do I really need to wait two weeks before adding my newly purchased primroses to my shade garden? — B.B., Olympia
A. Hardening off is a gardening term for slowly letting greenhouse-grown plants become used to cold nights. The weather forecast is the best indicator of how long your new plants should sit on a covered porch or patio adjusting to cold night temperatures in early spring. Three to five days is a suitable time for most greenhouse plants to toughen up, but primroses are a different story. Some varieties are tough enough to go right from the nursery into the ground, especially if you have a protected shade garden and no deep freeze is expected for a several days.
One tip is to cover newly added plants with a plastic milk jug that has the bottom cut out of it to keep wind and frost from damaging the blooms. Some gardeners keep an old sheet handy and drape this over newly planted blooms at night if a cold spell under 40 degrees is expected.
Q. When is a good time to divide my huge hosta plant? I would like to spread it around under the shade trees in my garden. — H.L., Tacoma
A. Dig and divide hosta in winter, spring, summer or fall — it doesn’t seem to matter at all unless the ground is frozen. Hosta is a perennial plant grown for its beautiful foliage and this shade-loving plant has thick roots so be warned that you may need an ax or sharp shovel to slice off sections of the root ball and replant them in other parts of the garden.
Marianne Binetti has a degree in horticulture from Washington State University and is the author of several books. Reach her at binettigarden.com.
This story was originally published March 23, 2024 at 5:00 AM.