Of the vegetables that are planted as seeds directly into the garden: Some are considered “cool-season” vegetables, which need a cool period to germinate, and others are “warm-season” vegetables, which need the soil to be warm enough to germinate and will not survive a frost. Here’s a helpful list:
Vegetables that have seeds that will germinate in cool soil are considered “cool-season” vegetables. Below is a list of those veggies which prefer to be seeded directly into the soil (not transplanted):
This plant is very hardy and can be planted 4-6 weeks before the average last frost date.
- Fava beans
It is possible to plant Hardy vegetables 2 to 3 weeks before the average last frost date.
“Warm-season” vegetables will only grow well in warm weather, and their seeds will only germinate if the ground is warm enough. If you plant them too early, the seeds may rot in the ground. Below is a list of those veggies which prefer to be seeded directly into the soil (not transplanted):
You can plant tender plants 0 to 2 weeks after a frost, as long as the frost hasn’t injured or killed them. Tender plants are also tolerant of cold weather.
- Snap beans
- Dry beans
- New Zealand spinach
- Summer squash
- Sweet corn
Warm-loving plants need to be planted 2 to 4 weeks after the last frost in order to prevent them from dying immediately from the cold weather. These plants are not tolerant of cold weather.
If the soil temperatures are under 60°F, the cucurbit seeds may rot.
- Garbanzo beans
- Lima beans
- Winter squash
- Yardlong Beans
Before Sowing Seeds
Here are some things to keep in mind before sowing seeds:
- Know Your Planting Dates. Before you even start planting, know when each vegetable should be planted.
- Have a Plan. Know where each vegetable will go. For example, consider which vegetables need shade and which vegetables are tall so they do not shade shorter plants. Also, plant so that you can reach the center of the row or bed easily enough to weed, water, and harvest. Provide permanent beds for perennial crops such as rhubarb, asparagus, and some herbs. Remember, you can plant cool-season crops in the same place as warm-season crops later in the season, based on the vegetable’s days to maturity (on the seed packet).
- Prepare the Soil. Your seeds need rich, fertile soil to grow. Add organic matter in the spring and work it into the soil, digging down about 1 foot to loosen the soil. Alternatively, do as many gardeners do and add organic matter in the fall so that it needs little work in the spring.
- Remove Weeds. Before you plant any seeds, the area MUST be weed-free! Otherwise, the weeds are competing for water and nutrients.
- Apply Fertilizer. In the spring—shortly before planting—work the fertilizer into the soil. A soil test will help determine soil deficiencies.
- Use Quality Seed. Seeds do have a shelf life, and while you can often get away with using older seeds, just be prepared for lower germination rates. Use fresh seed from a reputable company for the best results. Also, if you save your own seeds, do not save seeds from hybrid plants. Most hybrid plants will not be “true” to their parent type, so you could end up with a completely different (and possibly disappointing) fruit or flower.
- Starting Indoors. For vegetables that grow slowly from seed, try starting seeds indoors several weeks before the planting dates. Vegetables that grow slowly from seed and are ideal to start indoors include tomatoes, broccoli, cabbage, cauliflower, eggplant, and peppers.
- Prepping Warm-Season Crops. Before planting warm-season crops, especially cucurbits, you can warm the soil with different techniques, such as forming a mound or hill and/or using black plastic. To form a hill, mound soil to make a low, broad hill about 8 to 10 inches high. Lay any black plastic on the soil surface as early as possible in the spring. Simply cut a hole in the plastic in the area where you want a plant to be located; the plastic will keep the soil warmer and suppress weeds around the plant.
- Protect Seedlings From Frost. If you plant in early spring, be prepared to insulate young seedlings from cold weather—from cloches to row covers.
How to Plant Seeds
Sowing seeds is pretty simple, but there are some tips and tricks to make it easier, including the following:
- Sow at the proper depth. In general, plant seeds at a depth two times the seed’s diameter, no deeper. However, do refer to the seed packet for this information. Some seeds only need to be pressed into the soil surface, as they need more light to germinate. For seeds at two or three times the depth, poke individual holes for seeds or create a furrow. You can use a pencil to poke holes if you wish!
- Pay attention to seed spacing. You can plant lettuce, radishes, carrots, and other small seeds densely, and then thin them to the correct spacing when the seedlings are small. In general, plan to sow some extra seeds, since not all seeds may germinate.
- Plant in defined rows if you are a beginner; don’t scatter widely. It’s easier to keep weeds down between rows and identify seedlings from weedlings. (Weeds don’t usually grow in rows!) Often, rows are spaced about a foot apart but refer to your seed packet for specifics.
- Firm the soil, once seeds are sown. This ensures good contact between seed and soil.
- Water new seeds gently! Don’t turn the hose on full strength and blast them or you’ll wash those seeds away or cause them to drift together. Use a fine, gentle mist to moisten the soil or let the water hose slowly trickle around the area.
- Prevent soil crusting. Weak seedlings (such as carrots) can struggle to break through the soil surface if a hard crust forms. After covering seeds with soil, add a thin layer of fine mulch or compost to help prevent crusting. When you plant, you can also mix in seeds that germinate quickly (such as radishes), which will break through the crust and allow weaker seedlings to grow.
- “Hill” vining plants. When direct-sowing large vining plants such as squash, melon, and cucumber, consider planting them on a hill. Each hill should be spaced 4 to 8 feet apart. Plant 4 to 6 seeds in a circle in 5-inch intervals on each hill. Thin when seedlings have 2 or 3 leaves. Remove all but 2 to 3 large, healthy, well-spaced plants per hill. More than 3 plants per hill will lead to crowding, a greater chance of disease, and lower yields.
- Mark the spot where you planted your row of vegetables; it’s very easy to forget, especially when you are trying to differentiate between seedlings and weeds! Use a popsicle stick to label rows, or anything that works for you!
Successful Summer Succession Planting
- Plan ahead. Check your seed inventory and order new varieties or fresh seed packets before you need to plant.
- When you’re ready to seed or transplant, work in a 1/2-inch layer of compost.
- Avoid transplanting seedlings in the heat of the day. If possible wait for a cloudy or rainy day, or plant in the late afternoon when the sun is less strong.
- If you’re in the middle of a heat wave, consider providing shade for newly seeded or transplanted crops with a mini hoop tunnel. Float a piece of row cover or shade cloth on the hoops to protect the bed from the hot sun.
- Keep newly seeded or transplanted crops consistently watered. Germination rates will plummet if seedbeds are allowed to dry out.
- Mulch! After you move seedlings (kale, cabbage, broccoli, kohlrabi, etc) into garden beds, water the soil well and mulch plants with straw or shredded leaves to hold soil moisture and reduce transplant stress.
One way to get a lot of use out of your containers is to succession plant. This means that you plant different crops in the same container at different times. Many crops take well to pots, planters, and window boxes, so this is a great option. In fact, when the heat of July and August causes cool-weather vegetables, like spinach, arugula, and mustard, to bolt, planting in pots in semi-shade can yield a high-quality crop.
5 Vegetables to Plant in July
1) Z’Oro zucchini
The Z’Oro squash is a great choice for planting in succession as it is easy and quick to grow, with fruits ready for harvesting in just 45 days. The fruits are a beautiful deep yellow color with a unique cylindrical shape, and are produced in great abundance. For the best quality crop, harvest when the fruits are five to seven inches long.
2) Bulldog collard
Bulldog is a vigorous variety of collard greens that is quick to grow and has blue-green leaves. It is resistant to bolting in summer and tolerant of cold in winter, making it a good choice for fall and winter harvesting. You can direct seed it in the garden or give the plants a head-start indoors under grow lights, moving them to the garden about 50 days before the first expected fall frost.
3) Green Magic broccoli
This type of broccoli is good for succession planting in the summer, with the large, semi-domed heads being ready to harvest in about two months after being transplanted. The seeds can be direct-seeded or started indoors and then moved into the garden after three to four weeks. The harvest typically begins in early to mid-autumn, but with protection, it can extend into winter.
4) Aspabroc F1 Baby Broccoli ‘Broccolini’
This broccoli does best in cool weather and can be seeded for a fall crop. Aspabroc is different from traditional broccoli because it produces small side-shoots instead of one big head. This type of broccoli is good for stir-fries, roasting, dipping, or steaming.
5) Mascotte bush bean
My favorite bush bean is Mascotte because it is an early-yielding variety that grows well in garden beds and pots, has compact growth, and bears a ridiculously large harvest of super tender, stringless green beans. The pods are produced above the foliage, making for very easy picking.
*Bonus veggies: Cucumbers, carrots, beets, kohlrabi, cabbage, and peas.
5 Vegetables to Plant in August
1) Imperial Green Spinach
Imperial Green is a great spinach option to sow in late summer as it is heat-tolerant, bolt-resistant, and resistant to common spinach diseases, like downy mildew. The deep green, arrow-shaped leaves are held upright on sturdy stems, making for easy harvesting. Enjoy it raw in salads or cooked in stir-fries or pasta.
2) Deep Purple mustard
Deep Purple mustard is a great way to add excitement to your late-summer salads. You can sow the seeds in pots or beds, or in cold frames in mid-autumn for winter harvesting.
3) Vulcan lettuce
This type of lettuce is very good-looking and also tastes great. It does well when grown in a container and would also looknice in a garden. If there is any of this lettuce left in the garden at the end of autumn, put a mini hoop tunnel over it to protect it from the cold weather.
4) Peppermint Swiss chard
This chard is a superstar that does well in the spring, summer, and fall. It can even do well in a cold frame or tunnel. It is perfect for pots and gardens. The stems are pink and white and the foliage is deep green. You can plant a fresh crop in mid-summer and get baby leaves in early autumn. Some of the plants can be left to mature so you can have a late-season harvest.
5) Market Express baby turnip
30-day turnips that are the size of ping pong balls are in high demand at farmers’ markets because the roots are tender and the leaves taste good. Baby turnips grow quickly and do well in late-summer and early-fall gardens. You can roast, stir fry, or sauté the roots, or eat them raw in salads and other dishes.
Other vegetables that can be used in this dish include turnips, radishes, arugula, kale, beets, and Asian greens.
Caring for Seeds and Seedlings
Make sure to take care of your plants once you have planted the seeds!
- Keep soil moist until the seed germinates. Watering seeds is critical. Never let the soil get dry; seedlings do not have a good root system and will dry out within hours, especially if it’s windy outside. Use drip irrigation or put the hose at ground level and let the water gently soak the planting area.
- You’ll need to thin seedlings to the right spacing when they are a couple of inches high. Don’t be scared to thin! If you don’t, your plants won’t have space and nutrients to grow and will crowd together.
- Protect seedlings. Some pests do love those tender seedlings, too. If you have critters or pests, there are a number of different techniques to protect your seedlings, including netting, row covers, and little plant collars.
- Provide trellises and supports such as poles or cages. For example, cucumbers need vertical supports to produce straight (rather than curved or malformed) fruit. Any vining or sprawling plant such as melons or pole beans also needs support. Tomatoes also need support or cages for their heavy fruit.