It's a perfect time to start putting together your seed order. For vegetable gardeners, it's really a good idea to start that process by thinking about what you really like to eat on an everyday basis for your main garden and consider a few new fun things to try out.
On the fun side, for example, if you've never grown edamame (edible soybean), hibiscus for herbal tea, Padron tapas peppers, Trombetta climbing summer squash or Wyatt’s Wonder super-giant pumpkins, this will be a good year to try them.
That said, I want to encourage everyone to wait before translating that planting urge into reality until the weather outdoors is truly ready. Traditionally, gardeners are often told to start tomatoes, peppers and eggplant seeds indoors “6 to 8 weeks before the last frost.” I do not think this is good advice. It just doesn't tell you much if you live where there is no hard frost, like Southern California. Even in much colder climates, it's hard to know when the last frost will be, given all the weather variability these last few years.
In everywhere but the most tropical parts of the country, we start the seeds for long season heat-loving plants like tomatoes, eggplant and peppers early indoors to give them a needed head start because they take so long to mature. Then we transplant robust seedlings into the garden and they never look back.
But other large-seeded summer vegetables like corn, beans, squash, cucumbers and gourds are best sown directly in the garden once weather has warmed into the 50 to 55°F (10-13°C.). They will thrive best when they are sown directly in the soil because they have tender tap roots. Transplanting purchased or indoor grown seedlings for these plants into the garden inevitably shocks and sets them back. If you sow them directly from seed they will grow like little dynamos and surpass any transplants easily.
Likewise, fast-growing summer flowers like sunflowers, zinnias, cosmos, marigolds also do much better if you sow them directly into the garden when the weather is warm and settled as described above. They will never be as vigorous or grow as quickly if you start them in pots or seed starting trays too early. I think it's a shame that so many retailers actually start offering warm season veggie plants like tomatoes when it still shivering cold outside. This trend seems to have gotten worse over the last few years. Resist the urge to buy these plants out of season and better yet, plan to start your own from seed at the right time. Your plants will reward you with great abundance and you'll have the real satisfaction and pleasure that comes from nurturing them from tiny seeds into full bearing plants. I never get tired of of this joy.