Unless you're an uber-hippy/environmentalist who washes with white vinegar and water, you're unlikely to be able to smoke that weed.
If you used Calico-n-Creme™ super-scented Agent Orange detergent, it may be difficult to rinse away enough of the chemicals to make it safe for cooking, but considering many people wash their weed when it's drenched in pesticide, it might work. But if you wash with organic, no additive, no fragrance detergent I'm pretty sure you can salvage that weed for cooking. At any rate, cooking seems safest and easiest.
As I understand it, when you wash your weed, you'll lose a lot of the flavor and fragrance, and I think, most of the green from the chlorophyll, but that isn't necessarily a bad thing for kitchen weed. So maybe check out the thread Huaca mentioned. There's a lot of back and forth unrelated to your topic, but you might find some tips for washing. The only thing I would worry about it is drying it properly to avoid mold growth.
When eating weed, the onset of the high can take up to 2 hours. I once waited 2.5 or 3 hours because the weed sweets were the dessert course at an 8-small course Moroccan-themed brunch. Digression: We made two different cannabis sweets: my friend made a delicate, light, crunchy, spicey (cayenne, cinnamon, cardamom, allspice, orange peel, turmeric) cookie and I made a pistachio baklava with canabutter. Pistachio and weed go together well. Mmmm. That was an incredibly fun day. 8 hours in the sun, finger-, brush-, drip-, spray-painting the extensive, broken-down fence around the yard. Lots of musicians, so live deranged music all day. Just trying to inspire you for when your salvaged, edible weed will be consumed.
I'm guessing you've eaten it before but just in case, the high is more intense, lasts longer (6-8 hours sometimes) and it guarantees lovely sleep. Once you experiment a little with dosages, you can find a dose that doesn't get you super-high (unless that's your goal), and that lasts about 2-3 hours.
thread digression: cooking suggestion
I don't know how much weed you have. If it's a fair amount, you may want to make clarified butter, then throw the weed into that and extract the THC. You will be left with a large chunk of clarified canabutter, which if you've prepared it correctly will last you for up to a couple of years. (The critical part is making sure to remove ALL milk solids from the butter while clarifying.)
I have a 2 year old container in the freezer that has lost some potency. (That's not a problem with this batch since we made it so strong that a dime sized piece would give us a strong high for 2-3 hours. The first time we tried it to test for strength, we dosed very conservatively and ended up high as FUCK for about 8 hours.) But most importantly, it has not become rancid or freezer-burned. I've had it in there so long since it's so strong, and because I don't get high very often anymore… Just in case you were wondering why anyone in her right mind would leave lovely canabutter like that uneaten for so long. It's a fair question.
We used extremely powerful, fragrant and tasty organically-grown, outdoor Mendocino buds to achieve the potency. We wanted to make it as strong as possible in order to use it in a wider range of recipes or so that we could just swallow a tiny piece and be ready to go. Canabutter is really versatile and it's my favorite way of preparing weed for ingestion. We usually use shake but this was a special experiment and I'm assuming that you have buds too.
PM if you are interested in recipes or techniques.