What is Prechilling?

What is meant by "prechilling"?

Most spring-flowering bulbs, including tulips and hyacinths, need a prolonged period of cold temperatures to grow and bloom properly. In much of the United States, this cold period is provided naturally by a winter spent in the ground. Bulbs planted in the Deep South, the desert southwest and coastal California (more or less from the San Francisco Bay area south) don't get the cold they need. To perform well, they must be placed in a refrigerator for 8 to 10 weeks before planting.

Who should prechill?

In general, gardeners in USDA Zones 7b-10 (excluding the Pacific Northwest and tidewater Virginia) should prechill bulbs before planting. The 7b line is not a hard one. Some gardeners in Zone 7b prechill; others don't. A lot depends on how cold the upcoming winter is. Since it's impossible to predict how severe a given winter will be, we recommend prechilling, just to be safe. (We advise gardeners in Zones 9 and 10 in the Southeast - coastal Texas and Louisiana and Central and South Florida - to avoid planting tulips entirely, prechilled or not.)

Do all bulbs need prechilling in mild-winter climates?

Most, but not all. The following bulbs do well without prechilling. (Note that not all of these bulbs are adapted to growing in Zones 8-10, with or without prechilling. See the individual items on this website for their zone ratings.)

  • Alliums
  • Amaryllis
  • Daffodils (Narcissus)
  • Paperwhites
  • Snowflake (Leucojum)
  • Spanish bluebells (Hyacinthoides)
  • Starflower (Ipheion)

How long do bulbs need to be prechilled?

Somewhere between 8 and 10 weeks--the longer the better. Bulbs that are to be planted in Southern California and anywhere near the Gulf Coast really need the full 10 weeks. Bulbs destined for Northern California, Dallas and the Atlanta area can generally perform well with 8 weeks of chilling. The prechilling mantra goes like this: More is better than less.

What will happen if I plant bulbs without prechilling them?

Bulbs that don't get sufficient chilling tend to be stunted. They may bloom, but the flowers often open down in the leaves. In general, you will have a smaller, shorter plant and flower.

Does prechilling ensure a great display?

Tulips hail from Central Asia, where springs are long and cool. Prechilling tricks the bulbs into "thinking" they've had a cold winter but does not prepare them for an early March heat wave or a late wintry blast when the flowers are in their prime. To our southern customers we say: "Prechill your bulbs, ensure they have the water they need from planting through bloom and keep your expectations modest. The quality of the display is in nature's hands."

Can I prechill bulbs myself?

Sure, and for small orders, that's what we recommend--to avoid the extra expense of having us do it and to adjust the prechilling schedule to suit your own. Many people put their bulbs in an extra fridge that is otherwise used to chill soft drinks or beer. You can put flowerbulbs in your main refrigerator if you have the space, but please be aware that bulbs shouldn't be stored with fruits or vegetables, which can give off ethylene gas. Ethylene is harmless to people but can injure flowerbulbs.

When do I prechill and when do I plant?

We suggest you order your bulbs before the end of September for delivery around the middle of October. When the bulbs arrive, place them in the refrigerator for 8-10 weeks. Your bulbs will be ready to plant between mid- and late December. Many people wait until early January to plant.

Does Colorblends prechill bulbs?

Yes. We charge a flat fee of $30 per order for prechilling. The fee covers handling (we have to move the bulbs into our cooler and organize them for later shipment) and the cost of electricity.

If you would like us to prechill your bulbs, please be sure to select your desired shipping week (see note below). We generally move prechill orders into our cooler in mid-October. If your bulbs need 8 weeks of chilling, we suggest shipping in mid-December. If they need 10 weeks, we suggest shipping in late December or early January. Your bulbs will generally arrive at your address 3-6 business days after they leave our warehouse.

Please note: It is very difficult for us to ship a prechill order earlier than its scheduled week. We pack our cooler starting with the last orders to be shipped and finishing with the first due out. There is no easy way for us to find an individual order in the mountain of bulb crates. PLEASE TAKE CARE TO CHOOSE A DATE YOU CAN LIVE WITH.

How do I request the Colorblends prechilling service?

If you order online, you will be given the prechill option during Checkout. If you order by phone, you can discuss prechilling with any member of our staff. And if you order by fax or mail, just note that you want your bulbs prechilled, specify a delivery week and add the $30 fee to your order.

Do prechilled bulbs require special handling at planting time?

No, but once you remove the bulbs from your refrigerator or they arrive on your doorstep, they must be planted RIGHT AWAY. Also make sure to keep the bulbs out of direct sun while they're awaiting planting. The chilling begins to wear off when bulbs are exposed to temperatures above 40 degrees F. So don't delay, get prechilled bulbs into the ground quickly.

Will prechilled bulbs bloom again in later years?

In general, no. You should treat prechilled bulbs as annuals. When they're finished blooming, pull them up and toss them on the compost pile. We've heard reports that some of the smaller bulbs (e.g., muscari and some of the wild tulips) are willing in some areas to come back in subsequent years, but you can't count on a repeat performance.

Need more information?

If you aren't sure whether you need to prechill bulbs or you have questions about the prechilling process, give us a call at 1 888 847 8637 or send us an email at info@colorblends.com. We'll be glad to help.

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