These spring blooming bulbs need to be planted in the fall months to do their best. As a general rule we suggest you try to plant by Thanksgiving. You can plant later,even in January... just don't forget to plant them as they won't hold over for next year without being in soil. Plant bulbs 4" to 6" below ground level. Planting deeper is okay, shallower is risky as they could freeze, but an added layer of mulch works to remedy that. Fertilize at time of planting with a full spectrum fertilizer to meet bulbs hearty appetites... if you can't or don't fertilize when planting, be sure to fertilize in the spring just as the blooms are fading. Winter rains will likely meet the needs of necessary watering throughout the winter and spring months. If bulbs are containerized or under a covered area, they will need to be watered throughout the winter.
Our types of bulbs are to be planted in the fall months and then grow in the soil during the winter season. They must be planted at depths that provide a safe barrier from the freezing temperatures. Here in the Pacific Northwest we can safely plant bulbs 6" inches underground and that will protect them even if the temperatures dip into the teens (F). In our area, standing water is more of a concern than the cold temperatures as bulbs do not like wet feet for an extended period of time. Good drainage is important and is also something to keep in mind when choosing a planting site. Bulbs that are planted in containers also need good drainage so be sure that your pots have drain holes in the bottom. And be careful about using the pot saucers during wet weather as they will fill with water and may not allow the pot to drain enough excess water and the bulbs could die.
Bulbs prefer soil conditions with a neutral pH of 7.0. They can tolerate a little variance though. If you know that your soil has a lower pH, of say 5.5, then you would want to add lime to that area to help raise the pH to higher levels. Tulips in particular do not do well over an extended time if pH levels are low. The best time to add lime to your soil is in the fall. Work it into the soil where you will plant your bulbs. Follow the instructions on the bag of lime for desired results.
After your daffodils and tulips bloom it is best to pick off the dying flowers and discard them. This is for two reasons: 1) as the flower head withers and decays it tends to mold; when this happens, the mold spores fall onto the live and growing foliage which can then infect the rest of the plant which stops the growing cycle; 2) a seed pod is located just beneath the flowerhead and if this is removed with the flower it allows all the energy of the plant to be put into the bulb and next years flower production.
Mice have a hearty appetite for tulip and crocus bulbs. And, with the help of a moles ability to dig through your freshly planted flower beds, the mice gain access to your bulbs. An alternative is to plant these bulbs in a container, such as a pot or can with holes in the bottom for drainage, and then plant pot in your landscape. This will protect them from those underground pests. Deer are also a problem for tulip flowers once they have sprouted up as they like to eat the flowers right off at the ground. So keep that in mind as you strategically place your plantings. Daffodil bulbs, on the other hand, are poisonous and are not bothered by rodents and animals.