Yes, big marigold blossoms may be hard to catch with a teaspoon. But, eye-it-out with a confident guesstimate, or grind the herbs & flowers in a spice-grinder individually and measure the powder. Or, work it to smaller bits in the mortar & pestle until you feel like you can make proportional measurements.
When you have it all proportioned, stir everything together in your bowl or give it a mix-together in the mortar & pestle. Make sure you have a heat/fire-proof vessel to burn it in - such as a small cast iron caldron not used for food, or some stone-carved or brass incense burners.
Some people just put a pile of the herbs into their burner, hold a lighter to it until it catches, and very gently blow over it until it gets a good smoldering & smoking burn. Alternatively, you can get your hands on some charcoal discs used for smoldering incense. Light the disc, put it in the burning vessel, and sprinkle your House Cleansing incense on top a bit at a time. It may eventually stop or slow down smoking - as it does, add some more incense or poke it about with a metal tong to burn anything not touching the charcoal. Every now and then, gently blowing over the charcoal will get some burn on a diminishing glow.
Once you've got it smoking, you can carry it around the house like a smudge, clearing the air and energy of each room & space. Or, you can leave it centered safely in the main room or space of your home. Remember to throw open those windows for some fresh air circulation if it gets too smokey. And, if you have a central air vent, you might safely place your Cleansing Blend on the side of the room near a return-vent. It will circulate the cleansing energy through the whole house. This is also especially good when using a sage smudge as well.
Happy healing & blessed House Cleansing to all of you!