How to Freeze Dry Flowers

Freeze Drying at Home

Buy a freeze drying machine online or from a home supply store. Freeze drying equipment is pretty expensive, usually over a thousand dollars, so if you only want to freeze dry this one time, it’s definitely not worth it. However, if you plan to do lots of freeze drying, you can buy a freeze dryer that’s made for home use. Once you buy the machine, read the instructions to make sure you’re using it properly.

Wait until your flowers are mature and open. When you freeze dry your flowers, they will stay in the state you freeze them in, so don’t freeze them all closed up. To get your flowers to open up more, try recutting their stems and letting them drink warm water. Use a deep vase so that flowers have a lot of water to help them open. You can freeze dry most kinds of flowers that are found in bouquets.

Let fresh-cut flowers absorb water for 12 hours before freezing. Recut the stems of your flowers using a sharp knife or scissors, staying careful not to smash or pierce the stem. Place the flowers in a vase or container with room-temperature water and let them absorb the water for 12 hours. Even though you will eventually be drying the flowers, you want them to absorb a lot of water right now so that dry in a full shape.

Remove the leaves and cut the stems to the desired length. Strip all the leaves from the stems of your flowers, and trim the stem to your desired length. The shorter your stem is, the faster the freeze drying process will take, so consider removing most of the stem. To decide how much stem to remove, think about how you plan to arrange your flowers when you are done.

Pre-cool the specimen chamber to −5 °F (−21 °C). This is a bit like preheating your oven before you start cooking, except in this case, you prepare your freeze dryer by cooling it down. Make sure your freeze dryer is plugged in and turned on, and then set the temperature and press the start button. If you’re unsure how to start cooling down your freezer, check the manual.

Space out the flowers on the dryer trays. If you are freezing a bouquet, you’ll have to take it apart so that the flowers can lay in a single layer on the tray. It’s okay if the flowers touch each other, but it’s best to have them spaced out on the trays. Most freeze dryer machines can freeze about three trays at once, so there’s no need to crowd all your flowers onto one tray. The flowers shouldn’t come up higher than the edges of the tray.

Put the trays into the machine before covering and sealing the door. Slide the trays into the slots in the specimen chamber. Then, cover the door with the blackout cover. The blackout cover comes with the machine and slides right over the door to provide extra insulation. Close the door tightly. The door to the chamber has to be completely sealed for the freeze drying to work. Some machines have locks or handles you have to turn to ensure that the door is fully closed. Double-check your directions to ensure you closed the machine properly with the right insulation.

Turn on the vacuum pump if your machine hasn’t started already. Some freeze drying machines will start the freeze drying process as soon as they are pre-cooled, but for other machines you will have to separately turn on the vacuum pump after you have loaded in the trays. If you’re not sure if your freeze dryer is on, check the manual for instructions specific to the brand of freeze dryer you have.

Freeze at −5 °F (−21 °C) for 1 day. Since you already pre-cooled your freeze dryer to −5 °F (−21 °C) you don’t need to make any adjustments. Just walk away from your freeze dryer and let it do its thing for an entire 24 hours. The freeze dryer will cool down your flowers and vacuum out the air to remove all the moisture while preserving their shape.

Increase the temperature by 5 °F (2.8 °C) every 2 days for 10 days. After the initial 24 hours at −5 °F (−21 °C), increase the temperature to 0 °F (−18 °C). Continue raising the temperature every other day after that. By the end of the 10 days, the temperature will be 20 °F (−7 °C). Sometimes flowers need to freeze dry for 12 days, but it’s best to stop after 10 days to check them.

Check your flowers for dryness after 10 days. Check if the flowers are done by touching them. If they feel cold, that means they still contain moisture and need to be freeze dried for more time, so put the trays back in the freeze dryer for another day. You can also check by cutting into one of the petals and seeing if there is any moisture. If they are done, remove the flowers from the trays. If you want, you can put your freeze dried flowers in a glass-covered frame for display.

Keep your flowers in a shadow box. Don’t just keep your freeze dried flowers lying around, because they are fragile and you put so much effort into making them. Instead, keep them in a shadow box, which is an enclosed glass-fronted display case. Make sure you buy a shadow box that is deep enough, so you don’t smash the flowers under the glass. You can hot glue the flowers into the box to keep them in place.

Hiring a Freeze Dryer

Make freeze drying appointment at least 3 weeks in advance. If you’re planning on freezing your wedding bouquet, you can often request this service from the same florist you are buying the bouquet from. If the florist you bought the flowers from doesn’t offer freeze-drying or you’re freezing your own flowers, find local professionals to freeze dry your flowers by searching “freeze dry flowers,” plus the name of your town or city. Freeze drying flowers often costs around $150 or more. As soon as you decide that you’ll be freezing your flowers, look for appointments.

Keep your flowers fresh by keeping them cool and in water. If you have to store them before your preservation appointment, keep your flowers in water away from a heat sources like a stove or vent. Keep them away from fruit also, because fruits can give off ripening gas that will speed up your flower’s decay. A great place to store your flowers is in a cool fridge, away from a vent, but if your bouquet doesn’t fit in the fridge, just put it someplace cool. Some people say that copper pennies help preserve flowers, but it doesn’t actually help.

Give your bouquet to the preservationist and collect it when it’s done. Many people like to have their freeze dried flowers framed in glass to help keep them safe, so be sure to specify which frame you would like when talking to the flower preservationist. The floral professional will freeze your flowers in special equipment that gets it well below freezing temperature, and then dried out so that all the water leaves the flowers without them losing their shape. Freeze drying flowers can take a long time, so you may have to pick up your flowers two or three weeks after you drop them off.