A GROWING CONCERN: Indoor plant forcing yields big results

TODAY MARKS THE “Ides of March.” The lion and the lamb continue to frolic around their monthly endeavor.

I was in a conversation on the garden bus two weeks ago with a lovely passenger who was asking about how elevation affects timing.

Of course, this month is right, so I will address this today.

This column is relevant to everyone, but it will be a real advantage to those who live in the foothills because cooler temperatures persist longer at higher elevations.

There are many gorgeous flowering plants that thrive in the higher elevations. These plants are called long-day plants. They require 90 days or more of growing before they begin good flower or foliage production.

In most cases, the length of development time by these plants can be greatly extended by cool soil temperatures (less than 60 degrees) and cool air temperatures (less than 64 to 68 degrees).

So when you are in higher elevations, this delay can tack on another 20 to 30 days to the blooming cycle and many gardeners only experience their zenith for a few weeks while the rest of you might have a couple of months before autumn’s early frost brings the curtain down.

Moreover, these are some of the best or most exotic plants around for adding pizzazz, color, texture or cutting flowers to your yard.

These plants include but are not limited to dahlias (my favorite flowering plants), tuberous begonias, canna lilies, pendulous begonias, caladiums, hanging fuchsias, tuber roses, elephant ears, calla lilies, liatris, agapanthas, alsroemeria and hollyhock.

Long-day plants are lovely specimens even though our spring conditions of cool soil and air temperatures severely suppresses production.

So what’s a good gardener to do?

Buy them in pots and force them indoors for a month in late May. Then at the end of the month, transplant them outdoors.

Let me stress that if you don’t provide a bright, sunny and warm location where you will care for and water these potted pretties often, don’t bother.

It will be a complete and utter waste of time because all you will produce are long, nasty, spindly, weak, yellow plants that will produce far worse than if they were planted directly outside in the cold ground.

A sunny, warm and bright location is the number one criteria for successful outdoor forcing. A greenhouse, hothouse, conservatory or even baker’s pie window is preferable over a sunny flat window sill.

The light coming through an ordinary window is one-sided and your plant will be prone to leaning towards the window, stretching badly. This, of course, can be corrected by rotating the plant daily.

After light condition requirements, there is warmth.

Indoors, the key is to keep soil temperatures above 64 degrees, so air temperature needs to be 67 degrees or more. This warm, bright light will bring these babies to full fruition.

Soil is our next crucial link and one should spare no expense in purchasing or mixing up a great batch of soil.

Your potting soil should be very rich in organics (30 to 50 percent of mix). It should be light — preferably having perlite and or vermiculite in it, as well as some sand and black dirt (20 to 30 percent).

After you have the soil mixed, add in some good organic nutrients. Lime will ensure the proper pH. Bone meal will help start new roots. Kelp or blood meals will add a nice slow release of nitrogen. Wood ash is wonderful as well, as is very decomposed manure or leaf molds.

Planting is next and begins with new or cleaned pots.

Wash old plastic pots thoroughly, as diseases can linger in old soil particles.

Dip the parts in a bleach solution of one ounce of bleach per gallon of water for 10 to 20 minutes, rinsing off very thoroughly afterwards, sterilizing the pots. Place an inch or two of soil in the bottom of the pot, place the plant root or tuber in and then gently and loosely scoop the soil around, filling the pot to the lip.

Do not, under any circumstances, push down or pack in the soil.

Very heavy and successive waterings will condense the soil around the plant without harming it. And that is exactly what you do next — water, water and water again. To fully settle the soil in and around the bulb, water the pot 7 or 8 times that day, three to five times the following day, then once a day for a week. Then water the pot as it begins to dry out.

After your first two heavy days of watering, place that pot in that nice sunny, warm spot and add shovelfuls of loving care.

You will be amazed at the rewards you reap come this summer.

Good luck.


Andrew May is a freelance writer and ornamental horticulturist who dreams of having Clallam and Jefferson counties nationally recognized as “Flower Peninsula USA.” Send him questions c/o Peninsula Daily News, P.O. Box 1330, Port Angeles, WA 98362, or email [email protected] (subject line: Andrew May).

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