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Best-Kept Secrets of Floral Foam

One of the most versatile materials in the arranger’s tool-kit is floral foam (commonly referred to as Oasis®, a brand name). Unfortunately, it seldom comes with instructions and is easily misused, with disappointing (if not disastrous) results. For these reasons, many arrangers shy away from it. But with proper instructions and a little practice, you can successfully add it to your arranging arsenal!

The secrets to using floral foam include:

  • How to wet the foam

  • How to fit it to the container

  • How to cut and insert flower stems

Wetting the Foam

First of all, you should understand that floral foam is a very light and fragile open-celled material. It should be handled very gently when dry to avoid crushing those tiny cells. The cells (which contain air when the foam is dry) are designed to pull water through the foam via capillary action. As water is pulled in, air is pushed out the other side. In wetting the foam, it is absolutely essential that air not be trapped inside any of the cells!

The best way to wet a foam block is to let it do what comes naturally – let it pull in the water. Just set the dry foam block on the surface of a basin of water with the water at least as deep as the thickness of the block. The foam block will slowly sink as it pulls in water from the bottom and pushes air out through the top. This takes a minute or two so be patient! I use the kitchen sink, first cleaned with soap and water to remove any trace of grease or oil, then half-filled with tap water.

I recommend using either plain tap water or a Listerine® antiseptic solution (3 to 4 TBS in 1 gallon of distilled water) to soak the block. Solutions of cut flower food (e.g.,FloralifeTM) will not flow as freely through the foam and will encourage bacterial growth, reducing the life of the arrangement

Fitting the Container

Fit the foam into the container. Once the foam block is wet, you will find that it is much heavier and tougher (more resilient to the touch). Now it can be carved to fit the container, using a sharp knife. In a shallow, open container, the foam is simply set in the middle, and held in place with a snug crisscross of floral adhesive tape. Note: this kind of tape is available at craft stores, adheres tightly to the dry surface of a container and stays in place even if water is splashed on it later. Do not substitute any other kind of tape!

In a tall container the foam should be carved to fit snugly, but not so tightly that the foam is difficult to push into the opening of the container. (Don’t crush those tiny cells!) The secret here is to put a square peg in a round hole. I usually cut foam with a square or octagonal profile to fit it into a round opening. Just turn the container upside-down and press the container opening against the foam block lightly to mark an outline for cutting. The corners squeezed a little to ensure a snug fit, but the sides of the block are not compressed at all. If the foam fits snugly in a container, a crisscross of tape is not required to hold it in place.

The square peg/round hole practice serves another function as well. This kind of fit leaves gaps through which water can be added to the container. If it is not possible to leave a gap, as with a small-necked container, fill the container with water before the foam is inserted and make sure a neck of foam reaches deeply into the enclosed reservoir.

Note: For a traditional design, the foam usually extends 2 or 3 inches above the rim of the container, so stems can be placed hanging over the rim. For a secure fit, have at least as much of the foam block inside the container as the amount extending above it.

You may need to put some filler material in the bottom of a tall container so the foam will be positioned high enough. Any clean, sterile material that will not deteriorate in water will do. Try washed sand in a container that needs more weight for stability, or plastic packaging peanuts if the container is already heavy. Do not recycle used (punctured) floral foam as filler. Punctured foam contains plant debris which will pollute the water in the new arrangement.

Note: unpunctured, used foam may be reused as filler, however, once foam has dried out, it cannot be re-wet, so make sure the used foam is not in an area that will be reached by thirsty plant stems.

Cutting and Inserting Stems

Cutting and Inserting Stems

It is absolutely essential for plant stems to be tightly wedged into the foam, to ensure transfer of water from foam cells into plant tissues. A wobbly fit between stem and foam is not only unattractive to the design, but is also deadly to the bloom! Cut all stems cleanly at a sharp angle and they will slice neatly through the foam. Also make all stem cuts under water to avoid intrusion of air into stem cells. If the stem is thorny, first trim thorns from the bottom 2 or 3 inches of the stem to keep thorns from shredding the floral foam.

Do not pre-punch holes in the foam! If the flower stem is weak or crooked, attach a wooden floral pick (which is also cut at a sharp angle). The floral pick comes with a wire attached which should be snugly wrapped around the rose stem and pick, running the wire down the length of the pick as it is wrapped around, to hold the two together.

One to 1-1/2 inches of stem is usually all that needs to be inserted into the foam for an upright placement. For a more horizontal placement, 2 inches will provide more security. To gauge the length of a stem for cutting, hold the stem in position in front of the arrangement and note where the surface of the foam would hit the stem. Cut the stem one to two inches past that point. If you push the stem a little too far into the foam, or if the stem hits an obstruction (like another stem), pull the stem out completely. Re-cut the stem (under water) to expose a fresh surface, then place it in a new, unbroken section of foam. DO NOT pull the stem out just a little bit. That will break the seal between stem and foam!

Note: for a stem that will be placed horizontally, position the cut surface on the top side of the stem. As gravity pulls the bloom down, the surface of the foam becomes a pivot point to the stem. This means that as the bloom tries to drop down, the cut end of the stem (inside the foam) will be pushed up (like a seesaw), pressing the cut surface of the stem tightly against the foam.

More pick tricks: to keep curved stems from rotating out of position, attach a floral pick to create a rudder that will keep the stem from twirling around its axis. If the stem is a little short, add a pick extending beyond the end of the stem, to give it more security. But don’t pick every stem in the arrangement, or you’ll soon run out of space in the foam!


  • Let dry foam sink into a basin of water.

  • Fit a square block into a round hole.

  • Cut all stems at a sharp angle.

  • Use floral picks for various tricks.

Final Tips

Estimate the length of a stem. Use just enough foam to hold the number of stems necessary for the

design. Three to four inches of foam extending above the rim of a container should hold a mass design of 30 stems, with each stem inserted no more than 2-inches into the foam! Two inches of foam extending above the edge should be sufficient for a simple line design. Carefully gauge the length and position of stems so you just poke once. Practice this! In traditional design, the foam is usually “clothed” with a light layer of greenery – a few stems of leatherleaf fern or other plant material. Remember! All stems inserted into the foam, even greenery and dried materials, should be cut at a sharp angle for a clean, tight fit.

In modern design, the foam may be visible, but should not be distracting. Hide it completely inside the container if possible; otherwise, trim it neatly, removing any excess (what is not required for structural integrity). Remember – once floral foam has been soaked, then has dried, it will not re-wet. However, you can store wet, unused foam in a zip-lock bag in the refrigerator for later use.

Floral Foam Success!

I’ve had a mass design, built with well-conditioned roses in tap-water-soaked floral foam, last for a week after the show. I’ve had designs built with floral foam travel 20 miles in a car without coming apart. The fact that I can build designs the day before a show, and have them look just as fresh the next day, has given me a competitive edge at eight national rose shows. It isn’t magic it’s just good craftsmanship. Now you know the secrets and you can do it too!

This article first appeared in the 1Q95 Rose Arrangers Bulletin, an official quarterly publication of the American Rose Society.

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