How To Jump Start Summer Blooming Bulbs

Today we are going to talk about How To Jump-Start Summer Blooming Bulbs. As most of you, that have been reading my posts for any length of time, know I live and garden in Zone 4b. If I waited until it was warm enough to start bulbs outdoors, it would be the end of summer before they bloomed. Of course, I could buy the plants, but why should I pay someone else to grow them, when I can do it myself. Plus, I’m sort of a gardening geek and I get a kick out of watching things grow.

Last fall I posted Over-Wintering Tender Bulbs and Tubers, like; tuberous begonias, dahlia tubers, caladium bulbs, elephant ears, canna lily bulbs and calla lily bulbs. Most of these tubers and bulbs are only winter hardy in the warmest of climates. I had grand expectations of over-wintering several bulbs, so I dug them up and had them laying out to dry a bit in the garage. Someone decided it was time to clean the garage last fall and threw them all away. True story! And, yes that certain someone is still living. He will be buying me new bulbs this spring and he doesn’t even know it.

So, if you over-wintered any bulbs, it’s time to get them planted and warmed up so they can get a head-start and be ready to go into pots or the ground when it’s warm enough outside. If you didn’t over-winter bulbs, like me, you can get them at most big box stores. I’ve also had good luck ordering bulbs and plants from Dutch Gardens, Bluestone Perennials and Longfield Gardens.

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The Best Summer Blooming Bulbs to Start Indoors

Caladium are gorgeous multi-colored leafed plants that thrive in warm, shady conditions.
Begonias are a flowering plant that do well in shade and also love being in containers.
Dahlias come in so many different varieties and make a wonderful addition to any flower garden.
Elephant Ears are a tropical plant that has huge elephant ear shaped leaves.
Canna Lilies are another tall tropical plant that have stalks of flowers in various colors.
Calla Lilies are a popular bouquet tube shaped flower.
Oriental or Asiatic Lilies are amazing flowers. Don’t start these too early because they really grow fast.
Gladiolus are awesome flowers to cut for bouquets.

Supplies for Starting Bulbs Indoors:

Bulbs or Tubers
Pots – 5 inch ones like this, or 6 inch ones like this (You don’t need new pots, I just recycle ones from plants I’ve purchased.)
Good potting mix like this or this one.
Early Start Chart to keep track of the date your bulb was planted and the date it emerged, as well as other notes. This will be great to refer back to the following year. Pick up yours in the Gardening Resources Library.

Have your bulb starting supplies delivered right to your door:

Steps for Starting Summer Blooming Bulbs Indoors:

Start your bulbs about 6 weeks (caladium bulbs take more like 8 weeks) before the last frost date in your gardening zone. If you aren’t sure of that date, you can look it up here.

Read the directions on your potting mix. Some potting mixes may need water added before starting to plant.

As a general rule of thumb, bulbs or tubers need to be planted a depth of 2 times their diameter. It’s best to follow directions on the package of bulbs or tubers, but if you don’t have the package, this gives you a place to start.

Fill your pot about half way with potting mix.

Place the bulb or tuber on top of the soil. Pay special attention to which end is up. With some bulbs it’s difficult to tell, but I generally put the hairy root side down and the side with nodules up.

Finish filling the pot with soil and tamp the soil down.

Water really well, unless your potting mix was wet to begin with. You want moist soil, but not soggy wet soil.

Next, place your potted bulbs into a tray like this, or something that will hold water run-off.

This step is totally optional, but I highly recommend using a heat mat underneath the tray. A heat mat helps to provide consistent soil temperatures. And, some bulbs like caladium bulbs take forever to send up shoots and I believe the heat from underneath really helps them along. If you have a really warm spot in front of a window, you may not need a heat mat.

Don’t forget to water, but don’t over water. Just a warning, if the soil stays wet or soggy for too long, the bulbs will rot. Don’t let your pots sit in water.

Once I start seeing growth, I do a little happy dance! Really, it doesn’t take much to get me excited. At this point the pots need a good light source. Unlike seedlings, my bulbs and tubers have always done fine in a sunny, south facing window. If the plants don’t have an adequate light source they will get very leggy and spindly. If you don’t have a sunny enough spot for them, consider putting them under grow lights. For more information about my light set-up, see my post on Indoor Seed Starting.

I usually wait until the temperatures are between 55 – 60 degrees at night before moving my plants outdoors. And then I wait until the soil temps are between 55 – 60 degrees before I plant them in the ground. Of course, I don’t measure the temperature of the soil, but rather I wait about two weeks of the nighttime temperatures being around 55 – 60 degrees to be sure the soil has warmed up.

Here is an example of what I do with some of the bulbs I start indoors. Years ago, I purchased this old wheelbarrow from an estate sale. We drilled holes in the bottom for drainage and I’ve used it every year since as a planter somewhere in my gardens. It’s a favorite of mine, but as a planter it takes a lot of plants to make it look full. The last few years, I’ve started both caladium and begonias to use in it and that makes it a little less expensive to fill. There are pictures of it here and here. This is a closeup of the tuberous begonia and caladium. They are just lovely additions to a shade garden.

Are you thinking about getting a jump on the season by Starting Summer Bulbs Indoors? I encourage you to give it a try. You’ll save a little money and it kind of scratches that gardening itch when you can’t actually get outside.

The Best Summer Blooming Bulbs to Start Indoors

Supplies for Starting Bulbs Indoors:

Steps for Starting Summer Blooming Bulbs Indoors:

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