Feeding season is April through October, (or may vary with the local climate), with a "rest period" during the summer. Do not place food in one small clump so that there is not enough room for all the snails to get to it. Snails eat solid food by rasping it away with their tongues. Feeding activity depends on the weather, and snails may not necessarily feed every day. Evening irrigation in dry weather may encourage feeding since the moisture makes it easier for the snails to move about.
Put the breeding snails in the breeding pens in April or early May. Feed until mid June when mating begins and the snails stop feeding. Snails resume eating after they lay eggs. Once snails have laid their eggs, you can remove the adult snails. This leaves more food and less crowding for the hatchlings.
Snails of the same species collected from different regions may have different food preferences. Some foods that snails eat are: Alyssum, fruit and leaves of apple, apricot, artichoke (a favorite), aster, barley, beans, bindweed, California boxwood, almost any cabbage variety, camomile, carnation, carrot, cauliflower, celeriac (root celery), celery, ripe cherries, chive, citrus, clover, cress, cucumbers (a favorite snail food), dandelion, elder, henbane, hibiscus, hollyhock, kale, larkspur, leek, lettuce (liked, and makes good snails), lily, magnolia, mountain ash, mulberry, mums, nasturtium, nettle, nightshade berries, oats, onion greens, pansy, parsley, peach, ripe pears, peas, petunia, phlox, plum, potatoes (raw or cooked), pumpkins, radish, rape, rose, sorrel, spinach, sweet pea, thistle, thornapple, tomatoes (well liked), turnip,wheat, yarrow, zinnia. They will eat sweet lupines, but will reject bitter lupines and other plants with high quinolizidine alkaloids. Snails also avoid plants that produce other defensive chemicals, defensive stem hairs, etc.
Snails usually prefer juicy leaves and vegetables over dry ones. If you feed snails vegetable trimmings, damaged fruit, and cooked potatoes, promptly remove uneaten food as it will quickly spoil. You may supply bran that is wet or sprinkle dry bran over leafy vegetables. The diet may consist of 20% wheat bran while 80% is fruit and vegetable material. Some growers use oats, corn meal, soybean meal, or chicken mash. Laying mash provides calcium, as does crushed oyster shells. Snails also may eat materials such as cardboard (but do not purposely feed it to them); they can eat through shipping cartons and escape. Snails may sometimes eat, within a 24-hour period, food equal to 10%, and occasionally as much as 20%, of their body weight. Active snails deprived of food will lose more than one-third of their weight before they starve to death--a process that takes 8 to 12 weeks. Estivating snails can survive much longer.
Supply calcium at least once a week if it is not available in the soil. It should not contain harmful salts or be so alkaline as to burn the snails. Mix calcium with wet bran or mashed potatoes and serve on a pan; this will keep any leftover food from rotting on the ground.
Some researchers use chicken mash for feed. You can cut a plastic pipe in half lengthwise to make two troughs which can be used as feeders for mash. Mix laying mash (used for egg-producing hens) into the feed to provide calcium for the snails' shells. Commercial chicken feeding mash is around 16% to 17% protein, from fish meal and meat meal, making it good for growing snails. Supplying mash to hatchlings might reduce cannibalism. Two feeds that snails like and that promote good growth are: (A) broiler finisher mash consisting of 7% broiler concentrate, 58% corn, 16% soya, 18% sorghum, 7 % limestone flour (40% Ca); and (B) chicken feed (pellets) for layers consisting of 5% layer concentrate, 10%, corn, 15% soya, 20% sorghum, 44% barley, 6% limestone flour (40%Ca).
Pellets are fine for larger snails, but mash is better for younger ones. Partially crush pellets if you feed them to young snails. Snails do not grow well if rabbit pellets are their primary diet. Snails show a distinct preference for moist feed. Ensure easy access to enough water if you feed snails dry mash.
Be sure to frequently clean the feed and water dishes. The amount of feed a snail eats depends very much on air humidity and on the availability of drinking water. You can serve clean drinking water in a shallow container to reduce the risk of the snail drowning. Some types of chicken waterers may be suitable. Other factors (e.g., temperature, light intensity, food preferences versus food supplied, etc.) also affect feeding. A compromise, until you find the optimum feed, is to feed half green vegetable material and half chicken feed/grain/animal protein.
Young H. aspersa readily eats milk powder. Its rapid rate of assimilation promotes rapid growth.