Forced daffodils blooming indoors in late winter

How to Start Bulbs for Forcing in Spring

Submitted 2 years ago
Created by
Henry Homeyer

It's Time to Plant Bulbs Inside

At the end of a week of gray, raw, and drizzly days, I was at my wit’s end. Even my intrepid corgi, Daphne, was less than fully excited about taking walks in the rain. So I did what works best for me: I planted bulbs indoors so that I can force them to bloom in late winter. And it worked. Planting bulbs always picks up my spirits.

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Almost any spring bulb can be kept in a pot indoors for 8 to 16 weeks (depending on the bulb type) and made to bloom. Choose early-blooming daffodils and they can be ready in 12 weeks. Tulips? About 16 weeks. ‘Triumph’ tulips are said to be the best for forcing. Crocus and other small, early bulbs can be ready in 8 to 10 weeks.

Tulips grow best outdoors, but can be forced indoors.

Your bulbs planted for forcing need a cold place to develop: 35 to 50 degrees F is right. A cold basement, garage or barn are possibilities. Even a spare fridge would be all right. But if the temperature goes below freezing for very long, the roots will stop growing – and growing roots is a big part of what has to happen now if you are to get good blossoms in late winter.

All a bulb needs is a growing medium and a little moisture. I often reuse the potting mix that I used for growing annual plants outdoors in summer. I just pull up the summer’s plants, fluff up the soil, add a little as needed, and make sure it is damp to start. If it is dry, I water it well before I plant my bulbs.

Daffodils bulbs ready to plant for forcing

It is good to check the moisture levels in your bulb containers once a month during the time the bulbs are dormant and the roots are growing. Depending on the temperature, humidity and soil type, the soil medium can dry out. If it gets too dry, your flowers might not bloom. But too much water is also not good: it can rot the bulbs. That is more likely to happen if you used ordinary garden soil, which I don’t recommend as it holds too much water.

Instead of soil, use potting mix, or make a potting mix using peat moss, perlite or vermiculite, and compost. The mix should be fluffy and light. Dry peat moss, as it comes out of the package, is very dry and takes time to moisten thoroughly. Get your potting mix nicely moistened before planting any bulbs.

So how close can you plant your bulbs? Basically as close as you want. I put 20 tulips in my window box which is roughly 36 inches long and 7 inches wide. In a round pot with an 10-inch opening I put 10 daffodils. An inch or two between bulbs is fine.

Bulbs can be placed close together for dramatic effect

I like to lay out my bulbs on top of the potting mix to see how I should space them. I don’t want to compress the soil, so I use a soup spoon or my fingers to make a hole for the bulb and pop it into place. Outdoors we plant tulips and daffodils 6 inches deep, but in a pot? There is often little space for soil over the tops of the bulbs. And I leave an inch of free space above the soil line so I can water without spilling.

Clay pots may look good to you, but they can allow moisture to evaporate quickly from the sides of the pot. Plastic, fiber glass or porcelain containers are better for bulbs because they hold the moisture of the potting mix, minimizing water loss.

Be sure to label each pot with the date planted, and what is planted. Later, that will tell you when you can bring it into the warmth. Often bulbs will send roots out through the holes in the bottom of the pot or send up green shoots telling you they are ready. But don’t rush the process. Tulips brought up early will have nice green leaves, but no flowers.

Window box sealed with plywood keeps out the rodents. Label with date, too.

Most bulbs that have been forced are not likely to flower the following year, even if you keep the foliage alive until spring and plant them outside. I’ve done it, and some daffodils will build up the energy to blossom after a while. 

You also need to remember that although daffodils are mildly poisonous and hence unattractive to rodents, most other bulbs signify “LUNCH” for mice and squirrels. Most of us living in the country have at least a few mice in the basement at this time of year. They are looking for a cozy place to spend the cold months, after all. Red squirrels are notorious when it comes to sneaking into old houses and causing mischief. So you must prevent rodents from getting to your bulbs stored inside.

Each year I bring in my big cedar window box and fill it up with bulbs for forcing. This year I decided to plant tulips in it, so I made a lid for it out of a scrap of plywood. I even screwed down the top to prevent industrious squirrels from lifting it up to get at the tulips. (“You hold it up, Larry”, I can imagine one saying, “I’ll get those tulips and toss them out.”). I made other lids for ceramic pots and placed a brick on each one.

Forced flowers are great on a snowy day

When it’s time to bring your bulbs into the warmth of the house, put them on a sunny window to develop blossoms, but keep them out of direct sun when the flowers open so they will last longer. Get some bulbs and pot them up soon. It will help you now – and in mud season!

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Henry is the author of 4 gardening books. My personal  website has been down for a couple of weeks, but is now up and running! Visit my website by clicking here.  

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