While a lot of May gardening is dedicated to moving plants into the ground, there is still plenty of seeding to be done. Inside, I'm starting late-planted vegetables like cucumbers, and a second round of annual flowers, like stock and celosia. Outside, I'm beginning to direct seed vegetables like corn and beans, and annuals like sunflowers. It's important to remember to stay on top of your succession planting during this busy time. And finally, there's no better time to start, reseed, or overseed your eco lawn.

Lawns

A clover lawn before being cut Credit: Amanda Blum

Take advantage of the last of the rains to help germinate your eco lawn or clover lawn. You don't have to convert your whole yard, either, if you're anxious about it. Carve out a smaller area to seed with clover to try it. Ideally, you’re not creating a monoculture of one kind of seed, so other low lying flowers can be added in like yarrow, English daisy, and multiple types of clover. I add traditional clover for winter coverage, and red and strawberry clover for the summer to get pops of color.

Annual flowers

In most parts of the U.S., you’ll start to get enough sunshine this month to direct seed outside, which just means you’ll plant the seeds in the soil, rather than try to grow seedlings inside to plant outside later. If you’re going to try to direct-seed annuals like wildflowers, they can start going in the ground as soon as you’ve reasonably passed the risk of frost. Pay attention to the packet for instructions as to the depth of seeds—many seeds cannot germinate by simply being sprinkled on top of the soil; they need cover of soil. Your sunflower seeds, for instance, need a depth of an inch or so. A good basic rule is that seeds need to be planted as deep as their size. So tiny seeds like celosia are ok to be sowed on the surface, but marigolds and zinnia must be planted about half an inch deep. If you want to scatter the seeds to get a more natural look rather than poke holes for the seeds, scratch up an area so there’s soil contact for the seeds, then scatter them and cover them by sprinkling soil on top and patting it down. Finish by watering. 

I plant a row of sunflowers on the edge of my garden every year. Credit: Amanda Blum

Remember that summer is finite, so if you haven’t planted annual flower starts and you want to direct seed, you’ll want to do so before the end of May—although you may succession-seed another round of flowers later this summer, like zinnias or sunflowers. Consider ideas like a flower wall, or a row of sunflowers at the edge of the property or garden to define the area.

Direct sown vegetables

While some people direct sow vegetables like tomatoes and peppers outside, for most of the U.S., the summer is simply too short to do so and get a reasonable yield of fruit. This is why people buy vegetable starts at the nursery. Some vegetables, though, are fast-growing and prefer not to have their roots disturbed, so seeding them in the garden is a fine idea, and now is the time to do so.

There's almost no reason to start beans inside; they grow quickly and have shallow roots, so they are best seeded outside. Remember that beans are either bush type or vine type, and both need support, but vining beans can grow ten to twelve feet tall: Strong support will be needed, as beans can easily pull a trellis down.

Cucumbers on a frame trellis Credit: Amanda Blum

Cucumbers are ideal to start outside, particularly cucamelons (Mexican sour gherkins, which have become quite popular the last few years). They germinate within a few weeks and prefer not to have their roots disturbed. You can succession plant your cucumbers, so put another round of seeds in the ground in a few weeks. Cucumbers can crawl on the dirt, but you'll get better use of space and cleaner cucumbers if you use a trellis designed for them.

when pumpkins are grown on trellises, you make slings for them to add support Credit: Amanda Blum

Pumpkins and squash are fine to seed in the dirt. Pumpkins benefit from a hilling process. A popular way to do this is to dump a bucket or two of compost into a pile, creating a hill, and then place two or three pumpkin seeds in each hill. If these are giant pumpkins, you'll thin the seedlings to one, but for regular size pumpkins, you can have two seedlings. I've also had tremendous success growing pie pumpkins or mini pumpkins on an arch, so the pumpkins hang down. I'll be doing that again this summer with black and white pumpkins.

Most squash will germinate quickly, and while you can pick up summer squash and zucchini starts, you have plenty of time to grow from seed in most climates. Give it a try this summer.

Corn should be grown in blocks for better pollination. Credit: Amanda Blum

Corn should always be direct seeded. It is easy to germinate, and it grows fast. Make sure you're planting corn in blocks of four by four feet, so there's enough corn to pollinate itself. Corn grows tassels, which are pollinated by the wind, so unless you have a big enough block of corn stalks, you won't get corn. Don't try to grow a short row or a few plants; you need a substantial block of plants.

Melons are similar to squash and cucumbers and can be direct sown outside—but remember that melons and those cucurbits can cross pollinate, so don't plant them close together or you'll end up with Franken-squash, a common garden occurrence.

Succession seeding

Be sure to take advantage of the last spring rain to germinate additional rounds of carrots. Since they need constant moisture during germination, the rain can carry the load here. This time of year, I leave the radish, lettuce, green onion, beet, and kohlrabi seeds outside in a protected spot so I’ll remember to seed them once a week. You don’t need to put out a packet’s worth each week, just the number that you’ll eat. It helps to mark rows as you go so you don’t plant in a spot you’ve already seeded. 

lettuce grown in troughs Credit: Amanda Blum

My favorite tip for having a summers’ worth of lettuce is to direct seed a long, low trough planter of lettuce, but you can just pick a corner of a planting bed. Dump the whole packet of seeds in and be sure to mix it with the top layer of soil so it’s distributed evenly. Water the area and as the seeds germinate, you'll have a planter packed with lettuce. But if it's too packed, it won’t grow much, so each week, I grab a scoop from the end of the planter, separate those seedlings, and plant them out in the garden beds. The planter acts as a holding space for lettuce most of the summer, and each week I pluck out a few to plant. 

Seeding inside

There are still seedlings I grow inside this time of year, despite the abundant sunshine because growing inside means less exposure to predators like squirrels, birds, and rabbits, and I can control the atmosphere. If it's a particularly bad year for slugs, for instance, I may choose to grow cucumbers inside as starts. Sometimes I grow them in both locations so I can sub a start in if a cucumber plant gets eaten.

I also grow a second round of flowers inside, like stock and celosia. These are delicate seeds that benefit from a lot of attention, so I find growing them inside in a controlled environment is easier. Then I can place the grown starts precisely where I want them.