Centaurea macrocephala | giant knapweed

You may place your order anytime to reserve plants for fall 2026 shipping. If you place multiple orders, we will combine plants into one box (or as many as needed) and any extra shipping charges will be refunded.

We will resume shipping as soon as temperatures cool in our location and yours. This can range from the beginning of September for northern locations to the end of October for hot locations (Texas). 

We will check in with you a week before shipping to make sure you receive your plants at a time that is convenient for you.

Live plants ship in spring and fall only. Plants may ship dormant, depending on variety and season. Shipping costs are most reasonable when bundling like size plants.

• 4-inch: 1-6 plants ship for $15.00 / 7-13 plants ship for $18.00 / 14-30 plants ship for $40.00
• 1-gal: 1-2 plants ship for $18.00 / 3-4 plants ship for $25.00 / 5-6 plants ship for $40.00
• trees & shrubs: $27.00-$40.00 each, height dependent
• seeds: $6.75 or free with orders over $15.00

We regret that we cannot ship internationally or to the following states: AK, AZ, CA, CO, FL, HI, ID, MT, NV, OR, UT, or WA.

Read more about our shipping policies here.

We will email you to schedule a day and time to collect your plants when they are ready in spring. Generally, plants can be collected from the nursery Monday through Sunday from 10am-4pm in Spring, Summer, and Fall.

We most commonly use the following pot sizes for perennials:

• 4-inch pot: 3.5" H x 3.5" W x 3.5" D
• 2-quart pot: 6" H x 5.25" W x 5.25" D
• 1-gallon pot: 6.87" H x 8" Dia (this is a true one gallon pot, not the smaller 'trade' one gallon pot used by many nurseries)

Check out our illustrated pot size guide here.

Representative trees & shrubs are photographed in their pots and posted on each plant page.

Sustainability is at the heart of what we do at The Old Dairy. We grow all of our plants outdoors without the use of chemicals, fertilizers, carbon fuels, or peat.

Many of our perennials are grown in the ground and dug upon order (this is especially true for larger sizes). This practice allows us to grow stronger, healthier plants using native soil, and ultimately reduces our impact on the environment.

Our open-pollinated seeds are collected from plants in our mother beds, which have never been treated with chemicals or sprays of any kind.

Read all about our sustainable practices here.